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1. Star Formation, Triggering

Author

Zavagno, Annie, Gargaud, Muriel, editor, Irvine, William M., editor, Amils, Ricardo, editor, Claeys, Philippe, editor, Cleaves, Henderson James, editor, Gerin, Maryvonne, editor, Rouan, Daniel, editor, Spohn, Tilman, editor, Tirard, Stéphane, editor, and Viso, Michel, editor

Published
2023
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2. Compact and high excitation molecular clumps in the extended ultraviolet disk of M83.

Author

Koda, Jin, Combes, Françoise, Rubio, Monica, Andersen, Morten, Bigiel, Frank, Gil de Paz, Armando, Junais, Lee, Amanda M, Meyer, Jennifer Donovan, Morokuma-Matsui, Kana, Yagi, Masafumi, and Zavagno, Annie

Subjects
STELLAR evolution, STAR formation, GALAXY formation, SPATIAL resolution, GALAXIES
Abstract

Context. The extended ultraviolet (XUV) disks of nearby galaxies show ongoing massive-star formation, but their parental molecular clouds remain mostly undetected despite searches in CO(1–0) and CO(2–1). The recent detection of 23 clouds in the higher excitation transition CO(3–2) within the XUV disk of M83 thus requires an explanation. Aims. We test the hypothesis introduced to explain the non-detections and recent detection simultaneously: The clouds in XUV disks have a clump-envelope structure similar to those in Galactic star-forming clouds, having dense star-forming clumps (or concentrations of multiple clumps) at their centers, which predominantly contribute to the CO(3–2) emission and are surrounded by less dense envelopes, where CO molecules are photo-dissociated due to the low-metallicity environment there. Methods. We utilize new high-resolution ALMA CO(3–2) observations of a subset (11) of the 23 clouds in the XUV disk of M83. Results. We confirm the compactness of the CO(3–2)-emitting dense clumps (or their concentrations), finding clump diameters below the spatial resolution of 6–9 pc. This is similar to the size of the dense gas region in the Orion A molecular cloud, a local star-forming cloud with massive-star formation. Conclusions. The dense star-forming clumps are common between normal and XUV disks. This may also indicate that once the cloud structure is set, the process of star formation is governed by the cloud's internal physics rather than by external triggers. This simple model explains the current observations of clouds with ongoing massive-star formation, although it may require some adjustment, for example including the effect of cloud evolution, to describe star formation in molecular clouds more generally. [ABSTRACT FROM AUTHOR]

Published
2024
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3. The Giant Molecular Cloud G148.24+00.41: gas properties, kinematics, and cluster formation at the nexus of filamentary flows.

Author

Rawat, Vineet, Samal, M R, Walker, D L, Ojha, D K, Tej, A, Zavagno, A, Zhang, C P, Elia, Davide, Dutta, S, Jose, J, Eswaraiah, C, and Sharma, E

Subjects
MOLECULAR clouds, KINEMATICS, STAR formation, STELLAR evolution
Abstract

Filamentary flows towards the centre of molecular clouds have been recognized as a crucial process in the formation and evolution of stellar clusters. In this paper, we present a comprehensive observational study that investigates the gas properties and kinematics of the Giant Molecular Cloud G148.24+00.41 using the observations of CO (1-0) isotopologues. We find that the cloud is massive (105 M⊙) and is one of the most massive clouds of the outer Galaxy. We identified six likely velocity coherent filaments in the cloud having length, width, and mass in the range of 14–38 pc, 2.5–4.2 pc, and (1.3–6.9) × 103 M⊙, respectively. We find that the filaments are converging towards the central area of the cloud, and the longitudinal accretion flows along the filaments are in the range of ∼ 26–264 M⊙ Myr−1. The cloud has fragmented into seven clumps having mass in the range of ∼ 260–2100 M⊙ and average size around ∼ 1.4 pc, out of which the most massive clump is located at the hub of the filamentary structures, near the geometric centre of the cloud. Three filaments are found to be directly connected to the massive clump and transferring matter at a rate of ∼ 675 M⊙ Myr−1. The clump hosts a near-infrared cluster. Our results show that large-scale filamentary accretion flows towards the central region of the collapsing cloud is an important mechanism for supplying the matter necessary to form the central high-mass clump and subsequent stellar cluster. [ABSTRACT FROM AUTHOR]

Published
2024
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4. Understanding the relative importance of magnetic field, gravity, and turbulence in star formation at the hub of the giant molecular cloud G148.24+00.41.

Author

Rawat, Vineet, Samal, M R, Eswaraiah, Chakali, Wang, Jia-Wei, Elia, Davide, Panigrahy, Sandhyarani, Zavagno, A, Yadav, R K, Walker, D L, Jose, J, Ojha, D K, Zhang, C P, and Dutta, S

Subjects
MAGNETIC fields, STAR formation, STELLAR magnetic fields, MAGNETIC flux density, MACH number, GRAVITY, MOLECULAR clouds, ACCRETION (Astrophysics)
Abstract

The relative importance of magnetic fields, turbulence, and gravity in the early phases of star formation is still not well understood. We report the first high-resolution dust polarization observations at 850  |$\mu$| m around the most massive clump, located at the hub of the Giant Molecular Cloud G148.24+00.41, using SCUBA-2/POL-2 at the James Clerk Maxwell Telescope. We find that the degree of polarization decreases steadily towards the denser portion of the cloud. Comparing the intensity gradients and local gravity with the magnetic field orientations, we find that local gravity plays a dominant role in driving the gas collapse as the magnetic field orientations and gravity vectors seem to point towards the dense clumps. We also find evidence of U-shaped magnetic field morphology towards a small-scale elongated structure associated with the central clump, hinting at converging accretion flows towards the clump. Our observation has resolved the massive clump into multiple substructures. We study the magnetic field properties of two regions, central clump (CC) and northeastern elongated structure (NES). Using the modified Davis–Chandrasekhar–Fermi method, we determine that the magnetic field strengths of CC and NES are ∼24.0 ± 6.0  |$\mu$| G and 20.0 ± 5.0  |$\mu$| G, respectively. The mass-to-flux ratios are found to be magnetically transcritical/supercritical, while the Alfv |$\acute{\text{e}}$| n Mach number indicates a trans-Alfv |$\acute{\text{e}}$| nic state in both regions. These results, along with Virial analysis, suggest that at the hub of G148.24+00.41, gravitational energy has an edge over magnetic and kinetic energies. [ABSTRACT FROM AUTHOR]

Published
2024
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5. Star Formation, Triggering

Author

Zavagno, Annie, Gargaud, Muriel, editor, Irvine, William M., editor, Amils, Ricardo, editor, Cleaves, Henderson James (Jim), II, editor, Pinti, Daniele L., editor, Quintanilla, José Cernicharo, editor, Rouan, Daniel, editor, Spohn, Tilman, editor, Tirard, Stéphane, editor, and Viso, Michel, editor

Published
2015
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7. Probing the global dust properties and cluster formation potential of the giant molecular cloud G148.24+00.41.

Author

Rawat, Vineet, Samal, M R, Walker, D L, Zavagno, A, Tej, A, Marton, G, Ojha, D K, Elia, Davide, Chen, W P, Jose, J, and Eswaraiah, C

Subjects
MOLECULAR clouds, DUST, STAR clusters, STELLAR populations, PROTOSTARS, DISTRIBUTION of stars, STAR formation
Abstract

Clouds more massive than about 105 M⊙ are potential sites of massive cluster formation. Studying the properties of such clouds in the early stages of their evolution offers an opportunity to test various cluster formation processes. We make use of CO, Herschel , and UKIDSS observations to study one such cloud, G148.24+00.41. Our results show the cloud to be of high mass (⁠|$\sim \, 1.1\times 10^5$| M⊙), low dust temperature (∼ 14.5 K), nearly circular (projected radius ∼ 26 pc), and gravitationally bound with a dense gas fraction of ∼18 per cent and a density profile with a power-law index of ∼−1.5. Comparing its properties with those of nearby molecular clouds, we find that G148.24+00.41 is comparable to the Orion-A molecular cloud in terms of mass, size, and dense gas fraction. From our analyses, we find that the central area of the cloud is actively forming protostars and is moderately fractal with a Q -value of ∼ 0.66. We also find evidence of global mass-segregation with a degree of mass-segregation (ΛMSR) ≈ 3.2. We discuss these results along with the structure and compactness of the cloud, the spatial and temporal distribution of embedded stellar population and their correlation with the cold dust distribution, in the context of high-mass cluster formation. We compare our results with models of star cluster formation, and conclude that the cloud has the potential to form a cluster in the mass range ∼ 2000–3000 M⊙ through dynamical hierarchical collapse and assembly of both gas and stars. [ABSTRACT FROM AUTHOR]

Published
2023
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8. Hi-GAL: The Herschel Infrared Galactic Plane Survey

Author

Molinari, S., Swinyard, B., Bally, J., Barlow, M., Bernard, J.-P., Martin, P., Moore, T., Noriega-Crespo, A., Plume, R., Testi, L., Zavagno, A., Abergel, A., Ali, B., André, P., Baluteau, J.-P., Benedettini, M., Berné, O., Billot, N. P., Blommaert, J., Bontemps, S., Boulanger, F., Brand, J., Brunt, C., Burton, M., Campeggio, L., Carey, S., Caselli, P., Cesaroni, R., Cernicharo, J., Chakrabarti, S., Chrysostomou, A., Codella, C., Cohen, M., Compiegne, M., Davis, C. J., de Bernardis, P., de Gasperis, G., Di Francesco, J., di Giorgio, A. M., Elia, D., Faustini, F., Fischera, J. F., Fukui, Y., Fuller, G. A., Ganga, K., Garcia-Lario, P., Giard, M., Giardino, G., Glenn, J:, Goldsmith, P., Griffin, M., Hoare, M., Huang, M., Jiang, B., Joblin, C., Joncas, G., Juvela, M., Kirk, J., Lagache, G., Li, J. Z., Lim, T. L., Lord, S. D., Lucas, P. W., Maiolo, B., Marengo, M., Marshall, D., Masi, S., Massi, F., Matsuura, M., Meny, C., Minier, V., Miville-Deschênes, M.-A., Montier, L., Motte, F., Müller, T. G., Natoli, P., Neves, J., Olmi, L., Paladini, R., Paradis, D., Pestalozzi, M., Pezzuto, S., Piacentini, F., Pomarès, M., Popescu, C. C., Reach, W. T., Richer, J., Ristorcelli, I., Roy, A., Royer, P., Russeil, D., Saraceno, P., Sauvage, M., Schilke, P., Schneider-Bontemps, N., Schuller, F., Schultz, B., Shepherd, D. S., Sibthorpe, B., Smith, H. A., Smith, M. D., Spinoglio, L., Stamatellos, D., Strafella, F., Stringfellow, G., Sturm, E., Taylor, R., Thompson, M. A., Tuffs, R. J., Umana, G., Valenziano, L., Vavrek, R., Viti, S., Waelkens, C., Ward-Thompson, D., White, G., Wyrowski, F., Yorke, H. W., and Zhang, Q.

Published
2010
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10. ATOMS: ALMA three-millimeter observations of massive star-forming regions – XIII. Ongoing triggered star formation within clump-fed scenario found in the massive (∼1500 M⨀) clump.

Author

Zhang, Siju, Wang, Ke, Liu, Tie, Zavagno, Annie, Juvela, Mika, Liu, Hongli, Tej, Anandmayee, Stutz, Amelia M, Li, Shanghuo, Bronfman, Leonardo, Zhang, Qizhou, Goldsmith, Paul F, Lee, Chang Won, Vázquez-Semadeni, Enrique, Tatematsu, Ken'ichi, Jiao, Wenyu, Xu, Fengwei, Wang, Chao, and Zhou, Jian-Wen

Subjects
STAR formation, SUPERGIANT stars, IONIZED gases, IONIZING radiation, GAS flow, PROTOSTARS
Abstract

Whether ionization feedback triggers the formation of massive stars is highly debated. Using ALMA 3-mm observations with a spatial resolution of ∼0.05 pc and a mass sensitivity of 1.1  |$\rm M_\odot$|  per beam at 20 K, we investigate the star formation and gas flow structures within the ionizing feedback-driven structure, a clump-scale massive (≳ 1500  |$\rm M_\odot$|⁠) bright-rimmed cloud (BRC) associated with IRAS 18290–0924. This BRC is bound only if external compression from ionized gas is considered. A small-scale (≲ 1 pc) age sequence along the direction of ionizing radiation is revealed for the embedded cores and protostars, which suggests triggered star formation via radiation-driven implosion (RDI). Furthermore, filamentary gas structures converge towards the cores located in the BRC's centre, indicating that these filaments are fueling mass towards cores. The local core-scale mass infall rate derived from H13CO+  J  = 1 − 0 blue profile is of the same order of magnitude as the filamentary mass inflow rate, approximately 1  |$\rm M_\odot$|  kyr−1. A photodissociation region (PDR) covering the irradiated clump surface is detected in several molecules, such as CCH, HCO+, and CS whereas the spatial distribution stratification of these molecules is indistinct. CCH spectra of the PDR possibly indicate a photoevaporation flow leaving the clump surface with a projected velocity of ∼2 km s−1. Our new observations show that RDI accompanied by a clump-fed process is operating in this massive BRC. Whether this combined process works in other massive BRCs is worth exploring with dedicated surveys. [ABSTRACT FROM AUTHOR]

Published
2023
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11. The Hi-GAL catalogue of dusty filamentary structures in the Galactic Plane

Author

Stefano Pezzuto, Alberto Noriega-Crespo, Manuel Merello, David Eden, Giuseppe Riccio, Luca Olmi, Fabio Vitello, Nicolas Peretto, Sergio Molinari, Eva Sciacca, Eugenio Schisano, G. Li Causi, P. Palmeirim, Annie Zavagno, M. T. Beltrán, A. M. di Giorgio, M. Benedettini, Anthony Peter Whitworth, Toby J. T. Moore, Massimo Brescia, Davide Elia, Marco Molinaro, Leonardo Testi, Ugo Becciani, L. Cambresy, G. Umana, A. Baldeschi, S. J. Liu, Alessio Traficante, Stefano Cavuoti, Istituto di Astrofisica e Planetologia Spaziali - INAF (IAPS), Istituto Nazionale di Astrofisica (INAF), INAF - Osservatorio Astronomico di Capodimonte (OAC), University of Naples Federico II, Liverpool John Moores University (LJMU), Space Telescope Science Institute (STSci), INAF - Osservatorio Astrofisico di Catania (OACT), School of Physics and Astronomy [Cardiff], Cardiff University, Departamento de Astronomia (DAS), Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), INAF - Osservatorio Astrofisico di Arcetri (OAA), Observatoire astronomique de Strasbourg (ObAS), Université de Strasbourg (UNISTRA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), INAF - Osservatorio Astronomico di Roma (OAR), INAF - Osservatorio Astronomico di Trieste (OAT), Instituto de Astrofísica e Ciências do Espaço (IASTRO), European Southern Observatory (ESO), Schisano, E., Molinari, S., Elia, D., Benedettini, M., Olmi, L., Pezzuto, S., Traficante, A., Brescia, M., Cavuoti, S., di Giorgio, A. M., Liu, S. J., Moore, T. J. T., Noriega-Crespo, A., Riccio, G., Baldeschi, A., Becciani, U., Peretto, N., Merello, M., Vitello, F., Zavagno, A., Beltran, M. T., Cambresy, L., Eden, D. J., Li Causi, G., Molinaro, M., Palmeirim, P., Sciacca, E., Testi, L., Umana, G., Whitworth, A. P., and University of Naples Federico II = Università degli studi di Napoli Federico II

Subjects
Milky Way, Stars: formation, Extinction (astronomy), FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Protein filament, ISM: cloud, 0103 physical sciences, Submillimeter: ISM, 010303 astronomy & astrophysics, Galaxy: structure, Solar and Stellar Astrophysics (astro-ph.SR), ISM, Astrophysics::Galaxy Astrophysics, QC, ISM: general, QB, Physics, Infrared: ISM, Spiral galaxy, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], 010308 nuclear & particles physics, Star formation, Molecular cloud, SM: clouds, Astronomy and Astrophysics, Dust, Extinction, Galactic plane, Galaxy: local interstellar matter, Astrophysics - Astrophysics of Galaxies, Galaxy, ISM: dust, Galaxy:structure, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA)
Abstract

The recent data collected by {\it Herschel} have confirmed that interstellar structures with filamentary shape are ubiquitously present in the Milky Way. Filaments are thought to be formed by several physical mechanisms acting from the large Galactic scales down to the sub-pc fractions of molecular clouds, and they might represent a possible link between star formation and the large-scale structure of the Galaxy. In order to study this potential link, a statistically significant sample of filaments spread throughout the Galaxy is required. In this work we present the first catalogue of $32,059$ candidate filaments automatically identified in the Hi-GAL survey of the entire Galactic Plane. For these objects we determined morphological (length, $l^{a}$, and geometrical shape) and physical (average column density, $N_{\rm H_{2}}$, and average temperature, $T$) properties. We identified filaments with a wide range of properties: 2$'$\,$\leq l^{a}\leq$\, 100$'$, $10^{20} \leq N_{\rm H_{2}} \leq 10^{23}$\,cm$^{-2}$ and $10 \leq T\leq$ 35\,K. We discuss their association with the Hi-GAL compact sources, finding that the most tenuous (and stable) structures do not host any major condensation and we also assign a distance to $\sim 18,400$ filaments for which we determine mass, physical size, stability conditions and Galactic distribution. When compared to the spiral arms structure, we find no significant difference between the physical properties of on-arm and inter-arm filaments. We compared our sample with previous studies, finding that our Hi-GAL filament catalogue represents a significant extension in terms of Galactic coverage and sensitivity. This catalogue represents an unique and important tool for future studies devoted to understanding the filament life-cycle., 38 pages, 29 figures, 3 appendices

Published
2020
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13. Stellar feedback and triggered star formation in the prototypical bubble RCW 120

Author

Karl Jacobs, Nicola Schneider, C. Guevara, Jürgen Stutzki, L. D. Anderson, Dylan J. Linville, Matteo Luisi, Markus Röllig, Alexander G. G. M. Tielens, Leisa K. Townsley, Christof Buchbender, M. Tiwari, Annie Zavagno, D. Russeil, Rolf Güsten, M. Justen, Bernd Klein, Patrick S. Broos, Robert Simon, S. Kabanovic, Rheinische Friedrich-Wilhelms-Universität Bonn, Centre de recherche sur les civilisations de l'Asie Orientale (CRCAO), École Pratique des Hautes Études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Collège de France (CdF (institution))-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Max-Planck-Institut für Radioastronomie (MPIFR), Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Instituto de RadioAstronomía Milimétrica (IRAM), Centre National de la Recherche Scientifique (CNRS), Physikalisches Institut [Köln], Universität zu Köln = University of Cologne, I. Physikalisches Institut [Köln], ANR-16-CE92-0035,GENESIS,GENeration et Evolution des Structures du milieu InterStellaire(2016), Leiden Observatory [Leiden], Universiteit Leiden, West Virginia University [Morgantown], Laboratory for Atmospheric and Space Physics [Boulder] (LASP), University of Colorado [Boulder], and Université Catholique de Louvain = Catholic University of Louvain (UCL)

Subjects
endocrine system, Astronomy, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Negative feedback, 0103 physical sciences, Galaxy formation and evolution, Astrophysics::Solar and Stellar Astrophysics, 010303 astronomy & astrophysics, Research Articles, Astrophysics::Galaxy Astrophysics, Line (formation), Positive feedback, Physics, Multidisciplinary, 010308 nuclear & particles physics, Stratospheric Observatory for Infrared Astronomy, Star formation, Molecular cloud, fungi, food and beverages, SciAdv r-articles, Astrophysics - Astrophysics of Galaxies, Stars, [SDU]Sciences of the Universe [physics], Astrophysics of Galaxies (astro-ph.GA), Astrophysics::Earth and Planetary Astrophysics, Research Article
Abstract

Radiative and mechanical feedback of massive stars regulates star formation and galaxy evolution. Positive feedback triggers the creation of new stars by collecting dense shells of gas, while negative feedback disrupts star formation by shredding molecular clouds. Although key to understanding star formation, their relative importance is unknown. Here, we report velocity-resolved observations from the SOFIA (Stratospheric Observatory for Infrared Astronomy) legacy program FEEDBACK of the massive star-forming region RCW 120 in the [CII] 1.9-THz fine-structure line, revealing a gas shell expanding at 15 km/s. Complementary APEX (Atacama Pathfinder Experiment) CO J=3-2 345-GHz observations exhibit a ring structure of molecular gas, fragmented into clumps that are actively forming stars. Our observations demonstrate that triggered star formation can occur on much shorter time scales than hitherto thought (, 8 Pages, 4 Figures, 1 Table (+16 Page Supplementary Materials with 10 Figures). Published in Science Advances on April 9th, 2021, with free open access to the online article available at https://advances.sciencemag.org/content/7/15/eabe9511

Published
2021
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14. HII regions and high-mass starless clump candidates II. Fragmentation and induced star formation at ~0.025 pc scale: An ALMA continuum study

Author

M. Figueira, F. Louvet, Yi-Long Wu, D. Russeil, Ana López-Sepulcre, Annie Zavagno, S. Zhang, Jinghua Yuan, Hauyu Baobab Liu, T. G. S. Pillai, Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Institut de RadioAstronomie Millimétrique (IRAM), Centre National de la Recherche Scientifique (CNRS), Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7), Centro de Matemática e Aplicações Fundamentais (CMAF), Universidade de Lisboa (ULISBOA), Franche-Comté Électronique Mécanique, Thermique et Optique - Sciences et Technologies (UMR 6174) (FEMTO-ST), Université de Technologie de Belfort-Montbeliard (UTBM)-Ecole Nationale Supérieure de Mécanique et des Microtechniques (ENSMM)-Université de Franche-Comté (UFC), and Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Physics, HII regions, stars: formation, Continuum (measurement), 010308 nuclear & particles physics, Star formation, ISM: structure, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, 01 natural sciences, Astrophysics - Astrophysics of Galaxies, stars: massive, Fragmentation (mass spectrometry), Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, techniques: interferometric, Astrophysics of Galaxies (astro-ph.GA), 0103 physical sciences, High mass, submillimeter: ISM, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR)
Abstract

The ionization feedback from HII regions modifies the properties of high-mass starless clumps (HMSCs, of several hundred to a few thousand solar masses with a size of ~0.1-1 pc), such as temperature and turbulence, on the clump scale. The question of whether the presence of HII regions modifies the core-scale fragmentation and star formation in HMSCs remains to be explored. We aim to investigate the difference of 0.025 pc-scale fragmentation between candidate HMSCs that are strongly impacted by HII regions and less disturbed ones. We also search for evidence of mass shaping and induced star formation in the impacted HMSCs. Using the ALMA 1.3 mm continuum with a resolution of ~1.3", we imaged eight candidate HMSCs, including four impacted by HII regions and another four situated in the quiet environment. The less-impacted HMSCs are selected on the basis of their similar mass and distance compared to the impacted ones to avoid any possible bias linked to these parameters. A total of 51 cores were detected in eight clumps, with three to nine cores for each clump. Within our limited sample, we did not find a clear difference in the ~0.025 pc-scale fragmentation between impacted and non-impacted HMSCs, even though HII regions seem to affect the spatial distribution of the fragmented cores. Both types of HMSCs present a thermal fragmentation with two-level hierarchical features at the clump thermal Jeans length ${\lambda_{J, clump}^{th}}$ and 0.3${\lambda_{J, clump}^{th}}$. The ALMA emission morphology of the impacted HMSCs AGAL010.214-00.306 and AGAL018.931-00.029 sheds light on the capacities of HII regions to shape gas and dust in their surroundings and possibly to trigger star formation at ~0.025 pc-scale in HMSCs. Future ALMA surveys covering a large number of impacted HMSCs with high turbulence are needed to confirm the trend of fragmentation indicated in this study., Comment: 30 pages, 20 figures, Accepted by A&A on November 24, 2020

Published
2020
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15. The SEDIGISM survey: Molecular clouds in the inner Galaxy

Author

Sarah Ragan, M. Riener, Nicola Schneider, M. T. Beltrán, L. D. Anderson, Ke Wang, S. N. X. Medina, S. Lopez, Andrew Rigby, Adam Ginsburg, P. Venegas, F. M. Montenegro-Montes, Frédérique Motte, Rodrigo Parra, Ricardo Finger, Annie Zavagno, M. Wienen, D. Russeil, Andrea Giannetti, Henrik Beuther, Karl M. Menten, Erik Muller, Álvaro Sánchez-Monge, C. Agurto, M. Mattern, Toby J. T. Moore, F. Mac-Auliffe, Silvia Leurini, Jens Kauffmann, Sergio Molinari, James Urquhart, V. S. Veena, Timea Csengeri, Alberto Sanna, P. Mazumdar, E. Gonzalez, L. Testi, Leonardo Bronfman, Min-Young Lee, Q. Nguyen-Luong, Ana Duarte-Cabral, Clare Dobbs, Jouni Kainulainen, Alessio Traficante, Peter Schilke, Th. Henning, Dario Colombo, J. P. Pérez-Beaupuits, Friedrich Wyrowski, K. Torstensson, Audra K. Hernandez, Sylvain Bontemps, Frederic Schuller, P. J. Barnes, Eugenio Schisano, David Eden, Riccardo Cesaroni, F. Azagra, Sümeyye Suri, Alex R. Pettitt, School of Physics and Astronomy [Cardiff], Cardiff University, European Southern Observatory (ESO), Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Max-Planck-Institut für Radioastronomie (MPIFR), Universitat Politècnica de Catalunya [Barcelona] (UPC), Max-Planck-Institut für Astronomie (MPIA), Max-Planck-Gesellschaft, FORMATION STELLAIRE 2020, Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), and ANR-16-CE92-0035,GENESIS,GENeration et Evolution des Structures du milieu InterStellaire(2016)

Subjects
Population, FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, 01 natural sciences, Virial theorem, QB460, 0103 physical sciences, education, 010303 astronomy & astrophysics, ComputingMilieux_MISCELLANEOUS, Astrophysics::Galaxy Astrophysics, Physics, education.field_of_study, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], 010308 nuclear & particles physics, Star formation, Molecular cloud, Velocity dispersion, Astronomy and Astrophysics, Astrophysics - Astrophysics of Galaxies, Galaxy, Interstellar medium, Stars, 13. Climate action, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA)
Abstract

We use the 13CO(2-1) emission from the SEDIGISM high-resolution spectral-line survey of the inner Galaxy, to extract the molecular cloud population with a large dynamic range in spatial scales, using the SCIMES algorithm. This work compiles a cloud catalogue with a total of 10663 molecular clouds, 10300 of which we were able to assign distances and compute physical properties. We study some of the global properties of clouds using a science sample, consisting of 6664 well resolved sources and for which the distance estimates are reliable. In particular, we compare the scaling relations retrieved from SEDIGISM to those of other surveys, and we explore the properties of clouds with and without high-mass star formation. Our results suggest that there is no single global property of a cloud that determines its ability to form massive stars, although we find combined trends of increasing mass, size, surface density and velocity dispersion for the sub-sample of clouds with ongoing high-mass star formation. We then isolate the most extreme clouds in the SEDIGISM sample (i.e. clouds in the tails of the distributions) to look at their overall Galactic distribution, in search for hints of environmental effects. We find that, for most properties, the Galactic distribution of the most extreme clouds is only marginally different to that of the global cloud population. The Galactic distribution of the largest clouds, the turbulent clouds and the high-mass star-forming clouds are those that deviate most significantly from the global cloud population. We also find that the least dynamically active clouds (with low velocity dispersion or low virial parameter) are situated further afield, mostly in the least populated areas. However, we suspect that part of these trends may be affected by some observational biases, and thus require further follow up work in order to be confirmed., 25 pages (+ appendices, 15 pages), 26 figures, MNRAS

Published
2020
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16. FEEDBACK: a SOFIA Legacy Program to Study Stellar Feedback in Regions of Massive Star Formation

Author

Aggm Tielens, C. H. M. Pabst, Henrik Beuther, Nicolas Reyes, Urs U. Graf, O. Ricken, Annie Zavagno, Heiko Richter, Karl M. Menten, Bhaswati Mookerjea, Helmut Wiesemeyer, R. Simon, M. Justen, Mark Wolfire, S. Kabanovic, L. D. Anderson, Antoine Gusdorf, Matteo Luisi, L. Bonne, Ronan Higgins, Christof Buchbender, K. Jacobs, John Bally, Friedrich Wyrowski, Yoko Okada, Markus Röllig, Timea Csengeri, R. Karim, M. Mertens, G. Sandell, Marc W. Pound, Volker Ossenkopf-Okada, J. Stutzki, M. Tiwari, E. Chambers, D. Russeil, Álvaro Sánchez-Monge, Rolf Güsten, Nicola Schneider, Sylvain Bontemps, C. Guevara, Universität zu Köln, FORMATION STELLAIRE 2020, Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), and Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Physics, H II region, 010504 meteorology & atmospheric sciences, Star formation, Molecular cloud, Giant molecular clouds – Astronomical instrumentation – H II regions – Interstellar clouds – Interstellar filaments – Molecular clouds – Observatories – Stellar wind bubbles – Submillimeter astronomy, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, 01 natural sciences, Astrophysics - Astrophysics of Galaxies, Galaxy, Interstellar medium, Stars, 13. Climate action, Space and Planetary Science, [SDU]Sciences of the Universe [physics], Astrophysics of Galaxies (astro-ph.GA), 0103 physical sciences, 010303 astronomy & astrophysics, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, O-type star, Line (formation)
Abstract

FEEDBACK is a SOFIA (Stratospheric Observatory for Infrared Astronomy) legacy program dedicated to study the interaction of massive stars with their environment. It performs a survey of 11 galactic high mass star-forming regions in the 158 μm (1.9 THz) line of [C II] and the 63 μm (4.7 THz) line of [O I]. We employ the 14 pixel Low Frequency Array and 7 pixel High Frequency Array upGREAT heterodyne instrument to spectrally resolve (0.24 MHz) these far-infrared fine structure lines. With a total observing time of 96h, we will cover ∼6700 arcmin2 at 14 1) angular resolution for the [C II] line and 6 3 for the [O I] line. The observations started in spring 2019 (Cycle 7). Our aim is to understand the dynamics in regions dominated by different feedback processes from massive stars such as stellar winds, thermal expansion, and radiation pressure, and to quantify the mechanical energy injection and radiative heating efficiency. This is an important science topic because feedback of massive stars on their environment regulates the physical conditions and sets the emission characteristics in the interstellar medium (ISM), influences the star formation activity through molecular cloud dissolution and compression processes, and drives the evolution of the ISM in galaxies. The [C II] line provides the kinematics of the gas and is one of the dominant cooling lines of gas for low to moderate densities and UV fields. The [O I] line traces warm and high-density gas, excited in photodissociations regions with a strong UV field or by shocks. The source sample spans a broad range in stellar characteristics from single OB stars, to small groups of O stars, to rich young stellar clusters, to ministarburst complexes. It contains well-known targets such as Aquila, the Cygnus X region, M16, M17, NGC7538, NGC6334, Vela, and W43 as well as a selection of H II region bubbles, namely RCW49, RCW79, and RCW120. These [C II] maps, together with the less explored [O I] 63 μm line, provide an outstanding database for the community. They will be made publically available and will trigger further studies and follow-up observations.

Published
2020
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17. The role of Galactic H II regions in the formation of filaments

Author

Nicolas Peretto, M. Figueira, Alexander Men'shchikov, Ph. André, Y. Shimajiri, D. Russeil, P. Palmeirim, Nicola Schneider, Vera Konyves, Annie Zavagno, H. Roussel, Timea Csengeri, S. N. Zhang, Gary A. Fuller, Frederic Schuller, Doris Arzoumanian, Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Institut Universitaire de France (IUF), Ministère de l'Education nationale, de l’Enseignement supérieur et de la Recherche (M.E.N.E.S.R.), Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Leibniz-Institut für Astrophysik Potsdam (AIP), School of Physics and Astronomy [Cardiff], Cardiff University, Kagoshima University, Instituto de Astrofísica e Ciências do Espaço (IASTRO), Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Jodrell Bank Centre for Astrophysics (JBCA), University of Manchester [Manchester], Jeremiah Horrocks Institute for Mathematics, Physics and Astronomy [Preston], University of Central Lancashire [Preston] (UCLAN), Institut d'Astrophysique de Paris (IAP), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), University Hospital of Cologne [Cologne], Supports from the French national programs on stellar and ISM physics (PNPS and PCMI)., Funding from the European Union’s Horizon 2020 research and innovation programmeunder grant agreement No 730562 [RadioNet]., ANR-16-CE92-0035,GENESIS,GENeration et Evolution des Structures du milieu InterStellaire(2016), ANR-11-BS56-0010,STARFICH,Vers une vision unifiée de la formation stellaire dans les galaxies : Origine de la structure filamentaire du milieu interstellaire, des cœurs pré-stellaires et des amas protostellaires vus avec Herschel(2011), ANR-05-BLAN-0215,ARTEMIS,ARchitectures de bolomètres pour des TElescopes à grand champ de vue dans le domaine sub-MIllimétrique au Sol(2005), ANR-11-LABX-0013,FOCUS,Des détecteurs pour Observer l'Univers(2011), and European Project: 291294,EC:FP7:ERC,ERC-2011-ADG_20110209,ORISTARS(2012)

Subjects
010504 meteorology & atmospheric sciences, Shell (structure), FOS: Physical sciences, Context (language use), Astrophysics, 01 natural sciences, Protein filament, ISM: individual objects: RCW 120, Ionization, 0103 physical sciences, H II regions, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), 0105 earth and related environmental sciences, Physics, F990, stars: formation, Star formation, Resolution (electron density), Astronomy and Astrophysics, Astrophysics - Astrophysics of Galaxies, Full width at half maximum, Stars, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), submillimeter: ISM, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

Massive stars and their associated ionized (HII) regions could play a key role in the formation and evolution of filaments that host star formation. However, the properties of filaments that interact with H regions are still poorly known. To investigate the impact of HII regions on the formation of filaments, we imaged the Galactic HII region RCW 120 and its surroundings where active star formation takes place and where the role of ionization feedback on the star formation process has already been studied. We used the ArT\'eMiS camera on the APEX telescope and combined the ArT\'eMiS data at 350 and 450 microns with Herschel-SPIRE/HOBYS. We studied the dense gas distribution around RCW 120 with a resolution of 8 arcsec (0.05 pc at a distance of 1.34 kpc). Our study allows us to trace the median radial intensity profile of the dense shell of RCW 120. This profile is asymmetric, indicating a clear compression from the HII region on the inner part of the shell. The profile is observed to be similarly asymmetric on both lateral sides of the shell, indicating a homogeneous compression over the surface. On the contrary, the profile analysis of a radial filament associated with the shell, but located outside of it, reveals a symmetric profile, suggesting that the compression from the ionized region is limited to the dense shell. The mean intensity profile of the internal part of the shell is well fitted by a Plummer like profile with a deconvolved Gaussian FWHM of 0.09 pc, as observed for filaments in low-mass star-forming regions. This study suggests that compression exerted by HII regions may play a key role in the formation of filaments and may further act on their hosted star formation. ArT\'eMiS data also suggest that RCW 120 might be a 3D ring, rather than a spherical structure, Comment: 8 pages, 8 figures, accepted by A&A

Published
2020
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18. HII regions and high-mass starless clump candidates I: Catalogs and properties

Author

Hauyu Baobab Liu, D. Russeil, Annie Zavagno, Jinghua Yuan, K. A. Marsh, Yi-Long Wu, M. Figueira, Frederic Schuller, and S. N. Zhang

Subjects
Physics, 010308 nuclear & particles physics, Star formation, media_common.quotation_subject, FOS: Physical sciences, Astronomy and Astrophysics, Context (language use), Astrophysics, Limiting, 01 natural sciences, Astrophysics - Astrophysics of Galaxies, Luminosity, Stars, Cross matching, Astrophysics - Solar and Stellar Astrophysics, 13. Climate action, Space and Planetary Science, Sky, Astrophysics of Galaxies (astro-ph.GA), 0103 physical sciences, High mass, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), media_common
Abstract

The role of ionization feedback on high-mass (>8 Msun) star formation (HMSF) is still highly debated. Questions remain concerning the presence of nearby HII regions changes the properties of early HMSF and whether HII regions promote or inhibit the formation of high-mass stars. To characterize the role of HII regions on the HMSF, we study the properties of a sample of candidates high-mass starless clumps (HMSCs), of which about 90% have masses larger than 100 Msun. These high-mass objects probably represent the earliest stages of HMSF; we search if (and how) their properties are modified by the presence of an HII region. We took advantage of the recently published catalog of HMSC candidates. By cross matching the HMSCs and HII regions, we classified HMSCs into three categories: 1) The HMSCs associated with HII regions both in the position in the projected plane of the sky and in velocity; 2) HMSCs associated in the plane of the sky, but not in velocity; and 3) HMSCs far away from any HII regions in the projected sky plane. We carried out comparisons between associated and nonassociated HMSCs based on statistical analyses of multiwavelength data from infrared to radio. Statistical analyses suggest that HMSCs associated with HII regions are warmer, more luminous, more centrally-peaked and turbulent. We also clearly show, for the first time, that the ratio of bolometric luminosity to envelope mass of HMSCs (L/M) could not be a reliable evolutionary probe for early HMSF due to the external heating effects of the HII regions. More centrally peaked and turbulent properties of HMSCs associated with HII regions may promote the formation of high-mass stars by limiting fragmentation. High resolution interferometric surveys toward HMSCs are crucial to reveal how HII regions impact the star formation process inside HMSCs., 28 pages, 32 figures, accepted by Astronomy & Astrophysics on 24, Feb, 2020

Published
2020

19. A Virgo Environmental Survey Tracing Ionised Gas Emission (VESTIGE)

Author

Stephen Gwyn, Annie Zavagno, Patrick R. Durrell, Médéric Boquien, Ming Sun, P. Côté, Baerbel Koribalski, Luca Cortese, E. Toloba, Matteo Fossati, Alessandro Boselli, Bernd Vollmer, Gerhard Hensler, Joel Roediger, Giuseppe Gavazzi, Stephanie Cote, V. Buat, Denis Burgarella, Jean-Charles Cuillandre, D. Russeil, Michele Fumagalli, G. Consolandi, Laura Ferrarese, Yannick Roehlly, Samuel Boissier, Boselli, A, Fossati, M, Cuillandre, J, Boissier, S, Boquien, M, Buat, V, Burgarella, D, Consolandi, G, Cortese, L, Cote, P, Cote, S, Durrell, P, Ferrarese, L, Fumagalli, M, Gavazzi, G, Gwyn, S, Hensler, G, Koribalski, B, Roediger, J, Roehlly, Y, Russeil, D, Sun, M, Toloba, E, Vollmer, B, Zavagno, A, Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7), Università degli Studi di Milano-Bicocca [Milano] (UNIMIB), Bordeaux population health (BPH), Université de Bordeaux (UB)-Institut de Santé Publique, d'Épidémiologie et de Développement (ISPED)-Institut National de la Santé et de la Recherche Médicale (INSERM), Shanghai Maritime University, Observatoire astronomique de Strasbourg (ObAS), Université de Strasbourg (UNISTRA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Universitätssternwarte der Ludwig-Maximiliansuniversität, Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Unidad de Astronomia, Facultad de Ciencias Basicas, Universidad de Antofagasta, Milano, International Centre for Radio Astronomy Research, University of Western Australia (ICRAR), National Research Council of Canada (NRC), Department of Physics and Astronomy, Youngstown State University, Institute for Computational Cosmology, Department of Physics, Durham University, Durham (ICC), Department of Astrophysics, University of Vienna, Turkenschanzstrasse 17, 1180, Vienna, Austria, Australian Telescope National Facility (ATNF), Astronomy Centre, Department of Physics and Astronomy, University of Sussex, Falmer, CSPAR and Physics Department, University of Alabama in Huntsville, Huntsville, Department of Physiscs, University of the Pacific, 3601 Pacific Avenue, Stockton, CA, 95211, USA, Observatoire astronomique de Strasbourg (OAS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS), Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Università degli Studi di Milano-Bicocca = University of Milano-Bicocca (UNIMIB), CDS, Centre de Données astronomiques de Strasbourg, Observatoire astronomique de Strasbourg, France + ESO, European Southern Observatory, Garching bei Muenchen, Allemagne, Université de Strasbourg (UNISTRA)-Université Louis Pasteur - Strasbourg I, and Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES)

Subjects
[SDU.ASTR.CO]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO], FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, [SCCO]Cognitive science, Intracluster medium, 0103 physical sciences, Galaxy formation and evolution, galaxies: interactions, Astrophysics::Solar and Stellar Astrophysics, 010303 astronomy & astrophysics, Galaxies: individual: NGC 4254, Astrophysics::Galaxy Astrophysics, Physics, Spiral galaxy, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], 010308 nuclear & particles physics, Star formation, Galaxies: evolution, Astronomy and Astrophysics, Galaxies: clusters: individual: Virgo, Virgo Cluster, Astrophysics - Astrophysics of Galaxies, Galaxy, Ram pressure, Galaxies: ISM, [SDU]Sciences of the Universe [physics], 13. Climate action, Space and Planetary Science, Galaxies: interaction, Astrophysics of Galaxies (astro-ph.GA), Spectral energy distribution, Astrophysics::Earth and Planetary Astrophysics, Galaxies: clusters: general, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

During pilot observations of the Virgo Environmental Survey Tracing Galaxy Evolution (VESTIGE), a blind narrow-band Halpha+[NII] imaging survey of the Virgo cluster carried out with MegaCam at the CFHT, we have observed the spiral galaxy NGC 4254 (M99). Deep Halpha+[NII] narrow-band and GALEX UV images revealed the presence of 60 compact (70-500 pc radius) star forming regions up to ~ 20 kpc outside the optical disc of the galaxy. These regions are located along a tail of HI gas stripped from the disc of the galaxy after a rapid gravitational encounter with another Virgo cluster member that simulations indicate occurred 280-750 Myr ago. We have combined the VESTIGE data with multifrequency data from the UV to the far-infrared to characterise the stellar populations of these regions and study the star formation process in an extreme environment such as the tails of stripped gas embedded in the hot intracluster medium. The colour, spectral energy distribution (SED), and linear size consistently indicate that these regions are coeval and have been formed after a single burst of star formation that occurred ~< 100 Myr ago. These regions might become free floating objects within the cluster potential well, and be the local analogues of compact sources produced after the interaction of gas-rich systems that occurred during the early formation of clusters., Accepted for publication on Astronomy & Astrophysics

Published
2018
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20. A Comprehensive Study of the Young Cluster IRAS 05100+3723: Properties, Surrounding Interstellar Matter, and Associated Star Formation.

Author

Yadav, R. K., Samal, M. R., Semenko, E., Zavagno, A., Vaddi, S., Prajapati, P., Ojha, D. K., Pandey, A. K., Ridsdill-Smith, M., Jose, J., Patra, S., Dutta, S., Irawati, P., Sharma, S., Sahu, D. K., and Panwar, N.

Subjects
INTERSTELLAR medium, STAR formation, ELECTRON density, SUPERGIANT stars, GAS analysis
Abstract

We present a comprehensive multiwavelength investigation of a likely massive young cluster “IRAS 05100+3723” and its environment with the aim to understand its formation history and feedback effects. We find that IRAS 05100+3723 is a distant (∼3.2 kpc), moderate-mass (∼500 M ⊙), young (∼3 Myr) cluster with its most massive star being an O8.5V type. From spectral modeling, we estimate the effective temperature and log g of the star to be ∼33,000 K and ∼3.8, respectively. Our radio continuum observations reveal that the star has ionized its environment, forming a H ii region of size ∼2.7 pc, temperature ∼5700 K, and electron density ∼165 cmâˆ'3. However, our large-scale dust maps reveal that it has heated the dust up to several parsecs (∼10 pc) in the range 17âˆ'28 K and the morphology of warm dust emission resembles a bipolar H ii region. From dust and 13CO gas analyses, we find evidence that the formation of the H ii region has occurred at the very end of a long filamentary cloud around 3 Myr ago, likely due to edge collapse of the filament. We show that the H ii region is currently compressing a clump of mass ∼2700 M ⊙ at its western outskirts, at the junction of the H ii region and filament. We observe several 70 ÎĽ m point sources of intermediate mass and class 0 nature within the clump. We attribute these sources as the second-generation stars of the complex. We propose that the star formation in the clump is either induced or being facilitated by the compression of the expanding H ii region onto the inflowing filamentary material. [ABSTRACT FROM AUTHOR]

Published
2022
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21. The Origin of [C ii] 158 μ m Emission toward the H ii Region Complex S235

Author

A. M. Sobolev, Z. Makai, M. R. Samal, Annie Zavagno, Maria S. Kirsanova, Pascal Tremblin, Morten Andersen, D. Russeil, Matteo Luisi, L. D. Anderson, Volker Ossenkopf-Okada, Nicola Schneider, West Virginia University [Morgantown], Gemini Observatory [Southern Operations Center], Association of Universities for Research in Astronomy (AURA), Laboratoire d'Astrophysique de Marseille (LAM), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), Physical Research Laboratory [Ahmedabad] (PRL), Indian Space Research Organisation (ISRO), Universität zu Köln, Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Institute of Astronomy of the Russian Academy of Sciences (INASAN), Russian Academy of Sciences [Moscow] (RAS), Ural State University, Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Universität zu Köln = University of Cologne, and ANR-16-CE92-0035,GENESIS,GENeration et Evolution des Structures du milieu InterStellaire(2016)

Subjects
ISM [INFRARED], H II region, H II REGIONS, 010504 meteorology & atmospheric sciences, Hydrogen, Infrared, chemistry.chemical_element, FOS: Physical sciences, Astrophysics, Lambda, 01 natural sciences, Ionization, 0103 physical sciences, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, Physics, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], Star formation, Green Bank Telescope, Astronomy and Astrophysics, PHOTOMETRIC [TECHNIQUES], Astrophysics - Astrophysics of Galaxies, Galaxy, chemistry, 13. Climate action, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), ISM [RADIO CONTINUUM]
Abstract

Although the 2P3/2-2P1/2 transition of [CII] at 158um is known to be an excellent tracer of active star formation, we still do not have a complete understanding of where within star formation regions the emission originates. Here, we use SOFIA upGREAT observations of [CII] emission toward the HII region complex Sh2-235 (S235) to better understand in detail the origin of [CII] emission. We complement these data with a fully-sampled Green Bank Telescope radio recombination line map tracing the ionized hydrogen gas. About half of the total [CII] emission associated with S235 is spatially coincident with ionized hydrogen gas, although spectroscopic analysis shows little evidence that this emission is coming from the ionized hydrogen volume. Velocity-integrated [CII] intensity is strongly correlated with WISE 12um intensity across the entire complex, indicating that both trace ultra-violet radiation fields. The 22um and radio continuum intensities are only correlated with [CII] intensity in the ionized hydrogen portion of the S235 region and the correlations between the [CII] and molecular gas tracers are poor across the region. We find similar results for emission averaged over a sample of external galaxies, although the strength of the correlations is weaker. Therefore, although many tracers are correlated with the strength of [CII] emission, only WISE 12um emission is correlated on small-scales of the individual HII region S235 and also has a decent correlation at the scale of entire galaxies. Future studies of a larger sample of Galactic HII regions would help to determine whether these results are truly representative., Comment: Accepted to ApJ

Published
2019
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22. SCOPE: SCUBA-2 Continuum Observations of Pre-protostellar Evolution – Survey Description and Compact Source Catalogue

Author

Karine Demyk, Mark G. Rawlings, Giuseppe Cosentino, Lixia Yuan, Gwanjeong Kim, Dimitris Stamatellos, Satoshi Ohashi, Dalei Li, Yasuo Doi, L. Harvey-Smith, Archana Soam, Anthony Peter Whitworth, Mark Thompson, Izaskun Jiménez-Serra, Gary A. Fuller, Huei-Ru Chen, Tae-Geun Ji, Oscar Morata, Chakali Eswaraiah, Jinyi Yang, Takeshi Sakai, Y. L. Yuan, Hiroko Shinnaga, David Cornu, Jonathan Rawlings, Walter Kieran Gear, Shaila Akhter, Yuri Aikawa, A. Chrysostomou, Fanyi Meng, Andrew Walsh, Christine D. Wilson, P. M. McGehee, M. Chen, Tomoya Hirota, Carsten Henkel, You-Hua Chu, E. Falgarone, S. Kim, Yuxin He, Johanna Malinen, Sung-ju Kang, Chin-Fei Lee, Xuepeng Chen, Miju Kang, Annie Hughes, V.-M. Pelkonen, Graham S. Bell, Woojin Kwon, Huawei Zhang, Bon-Chul Koo, E. Jarken, Glenn J. White, J. X. Ge, Andrew Rigby, A-Ran Lyo, Wayne S. Holland, Hong-Li Liu, Geumsook Park, Mengyao Tang, Emily Drabek-Maunder, Hee-Weon Yi, M. Liu, Tie Liu, Rebeka Bögner, J.-P. Bernard, C. P. Zhang, B. S. Wang, Manash R. Samal, Harriet Parsons, Mika Juvela, Toby J. T. Moore, Lei Zhu, Ya-Wen Tang, Guobao Zhang, Leonardo Bronfman, George J. Bendo, S. Mairs, Serena Viti, H. Wang, Tetsuo Hasegawa, Yuxin Lin, Minho Choi, Zhiyuan Ren, Ke Wang, Yi-Jehng Kuan, David Eden, I. Ristorcelli, Lei Qian, X. Chen, Paul F. Goldsmith, Jinhua He, Diego Mardones, Shih-Ping Lai, Di Li, Soojong Pak, Qizhou Zhang, Ken'ichi Tatematsu, L. Montier, Yuefang Wu, C. Zhou, Guido Garay, Patricio Sanhueza, A. Rivera-Ingraham, Nicolas Peretto, Keping Qiu, Siyi Feng, Patrick M. Koch, Neal J. Evans, Jeong-Eun Lee, Andrew Blain, A. P. Marston, Hua-bai Li, M. Fich, Chao Zhang, Eun Jung Chung, G. Luo, J. Montillaud, Derek Ward-Thompson, Jianjun Zhou, Maria Cunningham, Jungha Kim, N. Lo, Roberta Paladini, J. Di Francesco, Jongsoo Kim, Ye Xu, Xing Lu, Charlotte Vastel, Chang Won Lee, Pak Shing Li, John A. P. Lopez, Per Friberg, Sheng-Li Qin, Gerald Moriarty-Schieven, D. Alina, G. Pech, Wen Ping Chen, O. Fehér, Pei Zuo, Sheng-Yuan Liu, Jinghua Yuan, Scott Chapman, Alessio Traficante, Doug Johnstone, Jane Greaves, Do-Young Byun, Naomi Hirano, Helen J. Fraser, Jiali Wang, Koji S. Kawabata, J. G. A. Wouterloot, X. Guan, Hsien Shang, Annie Zavagno, John Richer, Kee-Tae Kim, Sarolta Zahorecz, Kate Pattle, Y. Lee, L. V. Toth, Kevin Lacaille, Department of Physics, Particle Physics and Astrophysics, Liverpool John Moores University (LJMU), Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA (UMR_8112)), Sorbonne Université (SU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), University of Arizona, Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Cergy Pontoise (UCP), and Université Paris-Seine-Université Paris-Seine-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Milky Way, Continuum (design consultancy), SPIRAL ARMS, FOS: Physical sciences, F800, Astrophysics, 01 natural sciences, ISM: clouds, Luminosity, STAR-FORMATION, CLUMP IDENTIFICATION, symbols.namesake, surveys, 0103 physical sciences, Planck, GOULD BELT SURVEY, 010303 astronomy & astrophysics, James Clerk Maxwell Telescope, Solar and Stellar Astrophysics (astro-ph.SR), QC, QB, Physics, LEGACY SURVEY, Spiral galaxy, stars: formation, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], 010308 nuclear & particles physics, Star formation, [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], ATLASGAL, Astronomy and Astrophysics, Galactic plane, 115 Astronomy, Space science, Astrophysics - Astrophysics of Galaxies, CLOUD, submillimetre: ISM, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, [SDU]Sciences of the Universe [physics], GAS, Astrophysics of Galaxies (astro-ph.GA), symbols, MILKY-WAY, [SDU.ASTR.GA]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Galactic Astrophysics [astro-ph.GA], COMPLETE SAMPLE
Abstract

We present the first release of the data and compact-source catalogue for the JCMT Large Program SCUBA-2 Continuum Observations of Pre-protostellar Evolution (SCOPE). SCOPE consists of 850-um continuum observations of 1235 Planck Galactic Cold Clumps (PGCCs) made with the Submillimetre Common-User Bolometer Array 2 on the James Clerk Maxwell Telescope. These data are at an angular resolution of 14.4 arcsec, significantly improving upon the 353-GHz resolution of Planck at 5 arcmin, and allowing for a catalogue of 3528 compact sources in 558 PGCCs. We find that the detected PGCCs have significant sub-structure, with 61 per cent of detected PGCCs having 3 or more compact sources, with filamentary structure also prevalent within the sample. A detection rate of 45 per cent is found across the survey, which is 95 per cent complete to Planck column densities of $N_{H_{2}}$ $>$ 5 $\times$ 10$^{21}$ cm$^{-2}$. By positionally associating the SCOPE compact sources with YSOs, the star formation efficiency, as measured by the ratio of luminosity to mass, in nearby clouds is found to be similar to that in the more distant Galactic Plane, with the column density distributions also indistinguishable from each other., 16 pages, 13 figures, 1 table. Accepted for publication in MNRAS

Published
2019
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23. Lack of high-mass prestellar cores in the starless MDCs of NGC6334

Author

Andrés E. Guzmán, Annie Zavagno, F. Louvet, T. Nony, S. Neupane, Laura Gomez, Leonardo Bronfman, D. Russeil, Guido Garay, Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Departamento de Astronomia (DAS), University of Connecticut (UCONN), Pontificia Universidad Católica de Chile (UC), Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA), and Beaussier, Catherine

Subjects
010504 meteorology & atmospheric sciences, ISM: structure, FOS: Physical sciences, Astrophysics, [SDU.ASTR] Sciences of the Universe [physics]/Astrophysics [astro-ph], 01 natural sciences, ISM: clouds, [SDU] Sciences of the Universe [physics], 0103 physical sciences, Emission spectrum, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, Physics, stars: formation, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], Star formation, Astronomy and Astrophysics, Methods observational, Astrophysics - Astrophysics of Galaxies, stars: massive, Stars, 13. Climate action, Space and Planetary Science, techniques: interferometric, [SDU]Sciences of the Universe [physics], Astrophysics of Galaxies (astro-ph.GA), High mass, methods: observational, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

Two families of models compete to explain the formation of high-mass stars. The quasi-static models predict the existence of high-mass pre-stellar cores sustained by a high degree of turbulence while competitive accretion models predict that high-mass proto-stellar cores evolve from low/intermediate mass proto-stellar cores in dynamic environments. We present ALMA (1.4 mm continuum emission and $^{12}$CO emission line) and MOPRA (HCO$^{+}$, H$^{13}$CO$^{+}$ and N$_2$H$^+$ molecular line emissions) observations of a sample of 9 starless massive dense cores (MDCs) discovered in a recent Herschel/HOBYS study that have masses and sizes ($\sim$110 M$_\odot$ and $r\sim$0.1 pc, respectively) similar to the initial conditions used in the quasi-static models. The MOPRA molecular line features show that 3 of the starless MDCs are subvirialized with $\alpha_{\rm vir}\sim$0.35, and 4 MDCs show sign of collapse. Our ALMA observations, on the other hand, show very little fragmentation within the MDCs whereas the observations resolve the Jeans length ($\lambda_{\rm Jeans}\sim$0.03 pc) and are sensitive to the Jeans mass (M$_{\rm Jeans}\sim$0.65 M$_\odot$) in the 9 starless MDCs. Only two of the starless MDCs host compact continuum sources, whose fluxes correspond to $, Comment: Accepted by A&A

Published
2019
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24. Multiwavelength study of the G345.5+1.5 region

Author

Leonardo Bronfman, N. U. Duronea, Cristian Lopez-Calderon, Annie Zavagno, L. A. Nyman, C. Hervías-Caimapo, M. Figueira, Laboratoire d'Astrophysique de Marseille (LAM), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), National Centre for Nuclear Research [Otwock], Narodowe Centrum Badań Jądrowych (NCBJ), and Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)

Subjects
HII regions, Infrared, Ciencias Físicas, Population, FOS: Physical sciences, Context (language use), Astrophysics, 01 natural sciences, Virial theorem, Stellar formation, purl.org/becyt/ford/1 [https], 0103 physical sciences, education, 010303 astronomy & astrophysics, ISM, Physics, education.field_of_study, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], 010308 nuclear & particles physics, Star formation, Astronomy and Astrophysics, purl.org/becyt/ford/1.3 [https], Galactic plane, Astrophysics - Astrophysics of Galaxies, Astronomía, Stars, Space and Planetary Science, [SDU]Sciences of the Universe [physics], Astrophysics of Galaxies (astro-ph.GA), Spectral energy distribution, CIENCIAS NATURALES Y EXACTAS
Abstract

Star-forming regions are usually studied in the context of Galactic surveys, but dedicated observations are sometimes needed when the study reaches beyond the survey area. Here, we studied the G345.5+1.5 region, which is located slightly above the Galactic plane, to understand its star formation properties. We combined the LABOCA and $^{12}$CO(4$-$3) transition line observations complemented with the Hi-GAL and $\it{Spitzer}$-GLIMPSE surveys to study the star formation toward this region. We used the Clumpfind algorithm to extract the clumps from the 870$\mu$m and $^{12}$CO(4$-$3) data. Radio emission at 36cm was used to estimate the number of HII regions and to remove the contamination from the free-free emission at 870$\mu$m. We employed color-color diagrams and spectral energy distribution slopes to distinguish between prestellar and protostellar clumps. We studied the boundedness of the clumps through the virial parameter. Finally, we estimated the star formation efficiency and star formation rate of the region and used the Schmidt-Kennicutt diagram to compare its ability to form stars. Of the 13 radio sources that we found using the MGPS-2 catalog, 7 are found to be associated with HII regions corresponding to late-B or early-O stars. We found 45 870$\mu$m clumps, and 107 $^{12}$CO clumps. More than 50\% of the clumps are protostellar and bounded and are able to host star formation. High SFR and SFR density values are associated with the region, with an SFE of a few percent. With submillimeter, CO transition, and short-wavelength infrared observations, our study reveals a population of massive stars, protostellar and bound starless clumps, toward G345.5+1.5. This region is therefore actively forming stars, and its location in the starburst quadrant of the Schmidt-Kennicutt diagram is comparable to other star-forming regions found within the Galactic plane., Comment: 20 pages - 15 figures

Published
2019
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25. Herschel-HOBYS study of the earliest phases of high-mass star formation in NGC 6357

Author

Stefano Pezzuto, M. Figueira, D. Russeil, Pierre Didelon, Kazi L.J. Rygl, Annie Zavagno, Sylvain Bontemps, J. Di Francesco, Davide Elia, M. Benedettini, Nicola Schneider, G. J. White, Eugenio Schisano, Frédérique Motte, Vera Konyves, Ph. André, T. Nony, Luigi Spinoglio, Alexander Men'shchikov, L. D. Anderson, J. Tigé, Q. Nguyen Luong, ITA, GBR, FRA, CAN, Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS), University of Cologne, Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), FORMATION STELLAIRE 2019, Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Center for Gravitational Wave Astronomy (CGWA), University of Texas Rio Grande Valley [Brownsville, TX] (UTRGV), Istituto di Astrofisica e Planetologia Spaziali - INAF (IAPS), Istituto Nazionale di Astrofisica (INAF), Jeremiah Horrocks Institute for Mathematics, Physics and Astronomy [Preston], University of Central Lancashire [Preston] (UCLAN), Korea Astronomy and Space Science Institute (KASI), Okayama University [Okayama], NAOJ Chile Observatory, National Astronomical Observatory of Japan (NAOJ), INAF - Osservatorio Astronomico di Bologna (OABO), Space Science and Technology Department [Didcot] (RAL Space), STFC Rutherford Appleton Laboratory (RAL), Science and Technology Facilities Council (STFC)-Science and Technology Facilities Council (STFC), Programme National de Physique Stellaire' (PNPS) and Programme 'Physique et Chime du Milieu Interstellaire' (PCMI) of CNRS/INSU, France, ANR-16-CE92-0035,GENESIS,GENeration et Evolution des Structures du milieu InterStellaire(2016), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112)), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7), and Okayama University

Subjects
Physics, education.field_of_study, stars: formation, 010504 meteorology & atmospheric sciences, Star formation, F510, Population, Astronomy and Astrophysics, Astrophysics, F500, Star (graph theory), 01 natural sciences, stars: massive, Spire, Stars, [PHYS.ASTR.GA]Physics [physics]/Astrophysics [astro-ph]/Galactic Astrophysics [astro-ph.GA], Space and Planetary Science, 0103 physical sciences, High mass, Spectral energy distribution, Protostar, education, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], 010303 astronomy & astrophysics, 0105 earth and related environmental sciences
Abstract

Aims: To constrain models of high-mass star formation it is important to identify the massive dense cores (MDCs) that are able to form high-mass star(s). This is one of the purposes of the Herschel/HOBYS key programme. Here, we carry out the census and characterise of the properties of the MDCs population of the NGC 6357 H II region. Methods: Our study is based on the Herschel/PACS and SPIRE 70-500 μm images of NGC 6357 complemented with (sub-)millimetre and mid-infrared data. We followed the procedure established by the Herschel/HOBYS consortium to extract ~0.1 pc massive dense cores using the getsources software. We estimated their physical parameters (temperatures, masses, luminosities) from spectral energy distribution (SED) fitting. Results: We obtain a complete census of 23 massive dense cores, amongst which one is found to be IR-quiet and twelve are starless, representing very early stages of the star-formation process. Focussing on the starless MDCs, we have considered their evolutionary status, and suggest that only five of them are likely to form a high-mass star. Conclusions: We find that, contrarily to the case in NGC 6334, the NGC 6357 region does not exhibit any ridge or hub features that are believed to be crucial to the massive star formation process. This study adds support for an empirical model in which massive dense cores and protostars simultaneously accrete mass from the surrounding filaments. In addition, the massive star formation in NGC 6357 seems to have stopped and the hottest stars in Pismis 24 have disrupted the filaments. Full Table C1, Tables C2-C5, the reduced Herschel FITS images and the column density FITS image are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/625/A134 Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.

Published
2019
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26. The effects of ionization feedback on star formation: A case study of the M16 H II region

Author

Jin-Long Xu, Si-Ju Zhang, Guoyin Zhang, Bing-Gang Ju, Chuan-Peng Zhang, Chang-Chun Ning, Ye Xu, Naiping Yu, Jinghua Yuan, Annie Zavagno, Xiao-Lan Liu, Chinese Academy of Sciences [Beijing] (CAS), Laboratoire d'Astrophysique de Marseille (LAM), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), Purple Mountain Observatory, Chinese Academy of Sciences [Changchun Branch] (CAS), Tibet University, and Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Physics, H II region, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], 010308 nuclear & particles physics, Star formation, Molecular cloud, Young stellar object, FOS: Physical sciences, Astronomy and Astrophysics, Radius, Astrophysics, 01 natural sciences, Astrophysics - Astrophysics of Galaxies, Radio telescope, Protein filament, Stars, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, [SDU]Sciences of the Universe [physics], Astrophysics of Galaxies (astro-ph.GA), 0103 physical sciences, 010303 astronomy & astrophysics, ComputingMilieux_MISCELLANEOUS, Solar and Stellar Astrophysics (astro-ph.SR)
Abstract

We aim to investigate the impact of the ionized radiation from the M16 HII region on the surrounding molecular cloud and on its hosted star formation. To present comprehensive multi-wavelength observations towards the M16 HII region, we used new CO data and existing infrared, optical, and submillimeter data. The 12CO J=1-0, 13CO J=1-0, and C18O J=1-0 data were obtained with the Purple Mountain Observatory (PMO) 13.7m radio telescope. To trace massive clumps and extract young stellar objects (YSOs) associated with the M16 HII region, we used the ATLASGAL and GLIMPSE I catalogs, respectively. From CO data, we discern a large-scale filament with three velocity components. Because these three components overlap with each other in both velocity and space, the filament may be made of three layers. The M16 ionized gas interacts with the large-scale filament and has reshaped its structure. In the large-scale filament, we find 51 compact cores from the ATLASGAL catalog, 20 of them being quiescent. The mean excitation temperature of these cores is 22.5 K, while this is 22.2 K for the quiescent cores. This high temperature observed for the quiescent cores suggests that the cores may be heated by M16 and do not experience internal heating from sources in the cores. Through the relationship between the mass and radius of these cores, we obtain that 45% of all the cores are massive enough to potentially form massive stars. Compared with the thermal motion, the turbulence created by the nonthermal motion is responsible for the core formation. For the pillars observed towards M16, the H II region may give rise to the strong turbulence., Comment: 18 pages, 12 figures, accepted for publication in A&A

Published
2019
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27. The Hi-GAL compact source catalogue – I. The physical properties of the clumps in the inner Galaxy (−71$_.^circ$0 < ℓ < 67$_.^circ$0)

Author

Takahiro Hayakawa, David Eden, Melvin Hoare, Francesco Strafella, F. Piacentini, Kenneth A. Marsh, Sergio Molinari, S. E. Jaffa, Pedro García-Lario, Alessio Traficante, Peter Schilke, Kengo Tachihara, G. Joncas, J.-P. Bernard, M. R. Pestalozzi, S. Martinavarro-Armengol, Amata Mercurio, Alessandro Costa, Friedrich Wyrowski, Eva Sciacca, Robert Butora, B. Maiolo, Joseph C. Mottram, Mark Thompson, D. Polychroni, H. Yamamoto, G. Li Causi, P. Palmeirim, M. Benedettini, D. Russeil, Hidetoshi Sano, Kazi L.J. Rygl, Eugenio Schisano, Stefano Cavuoti, Annie Zavagno, Sarah Ragan, John Bally, M. Veneziani, Carla Buemi, A. P. Whitworth, K. Torii, Massimo Brescia, Péter Kacsuk, Davide Elia, Marco Molinaro, Nicola Schneider, Ugo Becciani, Rene Plume, Göran Pilbratt, A. M. di Giorgio, F. Faustini, P. Mège, Luca Calzoletti, Grazia Umana, Stefano Pezzuto, H. Arab, E. Fiorellino, Derek Ward-Thompson, S. J. Liu, Marilena Bandieramonte, M. T. Beltrán, Paolo Leto, Y. Maruccia, Roberta Paladini, Toby J. T. Moore, Giuseppe Riccio, Fabio Vitello, Luca Olmi, N. Marchili, Frédérique Motte, Corrado Trigilio, Ákos Hajnal, Yasuo Fukui, Nicolas Peretto, Alberto Noriega-Crespo, A. Baldeschi, Riccardo Cesaroni, Leonardo Testi, Lorenzo Piazzo, Manuel Merello, L. Cambrésy, Filomena Bufano, Peter G. Martin, Nicolas Billot, Meng-Lin Huang, Paolo Natoli, Elia, D., Molinari, S., Schisano, E., Pestalozzi, M., Pezzuto, Marilena, Merello, M., Noriega-Crespo, A., Moore, T. J. T., Russeil, D., Mottram, J. C., Paladini, R., Strafella, F., Benedettini, M., Bernard, J. P., Di Giorgio, A., Eden, D. J., Fukui, Y., Plume, R., Bally, J., Martin, P. G., Ragan, S. E., Jaffa, S. E., Motte, F., Olmi, L., Schneider, N., Testi, L., Wyrowski, F., Zavagno, A., Calzoletti, L., Faustini, F., Natoli, P., Palmeirim, P., Piacentini, F., Piazzo, L., Pilbratt, G. L., Polychroni, D., Baldeschi, A., Beltrán, M. T., Billot, N., Cambrésy, L., Cesaroni, R., García-Lario, P., Hoare, M. G., Huang, M., Joncas, G., Liu, S. J., Maiolo, B. M. T., Marsh, K. A., Maruccia, Y., Mège, P., Peretto, N., Rygl, K. L. J., Schilke, P., Thompson, M. A., Traficante, A., Umana, G., Veneziani, M., Ward-Thompson, D., Whitworth, A. P., Arab, H., Bandieramonte, M., Becciani, U., Brescia, M., Buemi, C., Bufano, F., Butora, R., Cavuoti, S., Costa, A., Fiorellino, E., Hajnal, A., Hayakawa, T., Kacsuk, P., Leto, P., Li Causi, G., Marchili, N., Martinavarro-Armengol, S., Mercurio, A., Molinaro, M., Riccio, G., Sano, H., Sciacca, E., Tachihara, K., Torii, K., Trigilio, C., Vitello, F., Yamamoto, H., Elia, Davide, Pezzuto, S., Noriega Crespo, A., Strafella, Francesco, García Lario, P., Maiolo, BERLINDA MARIA TERESA, Maruccia, Ylenia, Ward Thompson, D., and Martinavarro Armengol, S.

Subjects
Astrophysics and Astronomy, Infrared, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, cataloghi astronomici, mezzo interstellare, osservazioni infrarosse, osservazioni submillimetriche, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, QC, QB, Physics, Spiral galaxy, 010308 nuclear & particles physics, Star formation, Spectral density, Astronomy, Astronomy and Astrophysics, Galactic plane, Galaxy, Stars, Space and Planetary Science, Astrophysics::Earth and Planetary Astrophysics, catalogues, ISM clouds, dust, extinction, local interstellar matter, infrared ISM, submillimetre ISM, Longitude
Abstract

Hi-GAL (Herschel InfraRed Galactic Plane Survey) is a large-scale survey of the Galactic plane, performed with Herschel in five infrared continuum bands between 70 and 500 μm. We present a band-merged catalogue of spatially matched sources and their properties derived from fits to the spectral energy distributions (SEDs) and heliocentric distances, based on the photometric catalogues presented in Molinari et al., covering the portion of Galactic plane −71 ∘. 0 < ℓ < 67 ∘. 0. The band-merged catalogue contains 100 922 sources with a regular SED, 24 584 of which show a 70-μm counterpart and are thus considered protostellar, while the remainder are considered starless. Thanks to this huge number of sources, we are able to carry out a preliminary analysis of early stages of star formation, identifying the conditions that characterize different evolutionary phases on a statistically significant basis. We calculate surface densities to investigate the gravitational stability of clumps and their potential to form massive stars. We also explore evolutionary status metrics such as the dust temperature, luminosity and bolometric temperature, finding that these are higher in protostellar sources compared to pre-stellar ones. The surface density of sources follows an increasing trend as they evolve from pre-stellar to protostellar, but then it is found to decrease again in the majority of the most evolved clumps. Finally, we study the physical parameters of sources with respect to Galactic longitude and the association with spiral arms, finding only minor or no differences between the average evolutionary status of sources in the fourth and first Galactic quadrants, or between ‘on-arm’ and ‘interarm’ positions. Hi-GAL is a large-scale survey of the Galactic plane, performed with Herschel in five infrared continuum bands between 70 and 500 $\mu$m. We present a band-merged catalogue of spatially matched sources and their properties derived from fits to the spectral energy distributions (SEDs) and heliocentric distances, based on the photometric catalogs presented in Molinari et al. (2016a), covering the portion of Galactic plane $-71.0^{\circ}< \ell < 67.0^{\circ}$. The band-merged catalogue contains 100922 sources with a regular SED, 24584 of which show a 70 $\mu$m counterpart and are thus considered proto-stellar, while the remainder are considered starless. Thanks to this huge number of sources, we are able to carry out a preliminary analysis of early stages of star formation, identifying the conditions that characterise different evolutionary phases on a statistically significant basis. We calculate surface densities to investigate the gravitational stability of clumps and their potential to form massive stars. We also explore evolutionary status metrics such as the dust temperature, luminosity and bolometric temperature, finding that these are higher in proto-stellar sources compared to pre-stellar ones. The surface density of sources follows an increasing trend as they evolve from pre-stellar to proto-stellar, but then it is found to decrease again in the majority of the most evolved clumps. Finally, we study the physical parameters of sources with respect to Galactic longitude and the association with spiral arms, finding only minor or no differences between the average evolutionary status of sources in the fourth and first Galactic quadrants, or between "on-arm" and "inter-arm" positions.

Published
2017

28. Chemistry of Protostellar Clumps in the High-mass, Star-forming Filamentary Infrared Dark Cloud G034.43+00.24

Author

Tie Liu, S. N. Zhang, Hong-Li Liu, Yuefang Wu, Xindi Tang, Annie Zavagno, Patricio Sanhueza, Xinjiang Institute of Ecology and Geography [Urumqi] (XIEG), Chinese Academy of Sciences [Beijing] (CAS), Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), and Peking University [Beijing]

Subjects
Physics, Astrochemistry, Star formation, Chemical abundances, Astronomy and Astrophysics, Interstellar molecules, Astrophysics, Star (graph theory), Interstellar medium, [SDU]Sciences of the Universe [physics], Space and Planetary Science, High mass, Infrared dark cloud
Abstract

To search for the potential chemical dependence on physical conditions, we have carried out the study of chemistry on the nine protostellar clumps of the high-mass star-forming infrared dark cloud G034.43+00.24, with observations of several \ensuremath∼1 mm lines by the Atacama Pathfinder EXperiment telescope. They include CO/^13CO/C^18O (2-1), HCO^+/H^13CO^+ (3-2), HCN/H^13CN (3-2), HNC (3-2), CS/C^34S (5-4), SiO (6-5), SO (6-5), p-H_2CO (3-2), and CH_3OH (5-4). All the clumps are simply grouped into two classes: high-luminosity protostellar clumps (MM1-MM4, L_\mathrmbol ∼ 10^3 L_\ensuremathødot) and low-luminosity protostellar clumps (MM5-MM9, L_\mathrmbol\ll 10^3 L_\ensuremathødot). Our observations indicate that ^13CO suffers either no or low depletion in the clump environment of G034.43+00.24 as characterized by a nearly constant level of the ^13CO abundance distribution. For the remaining relatively dense gas tracers, we find that their abundances tend to get enhanced in the high-luminosity protostellar clumps as opposed to the low- luminosity counterparts. We suggest that for most, if not all, of the dense gas tracers the high abundance mainly arises from both the high luminosities and associated outflows of the high- luminosity protostellar clumps while the low abundance could be due to the lack of such active star-forming activities in the low-luminosity protostellar clumps. * This publication is based on data acquired with the Atacama Pathfinder Experiment (APEX) under program ID 0104.F-9708. APEX is a collaboration between the Max-Planck-Institut fur Radioastronomie, the European Southern Observatory, and the Onsala Space Observatory.

Published
2020
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29. Bipolar H II regions: II. Morphologies and star formation in their vicinities

Author

D. Russeil, Manash R. Samal, Annie Zavagno, Lise Deharveng, Sergio Molinari, L. D. Anderson, Laboratoire d'Astrophysique de Marseille (LAM), and Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Physics, Nebula, 010308 nuclear & particles physics, Star formation, extinction, stars : formation, Young stellar object, Extinction (astronomy), Astronomy and Astrophysics, Bipolar nebula, Astrophysics, Galactic plane, 01 natural sciences, dissemin, law.invention, Stars, 13. Climate action, Space and Planetary Science, law, [SDU]Sciences of the Universe [physics], 0103 physical sciences, H II regions, dust, Maser, 010303 astronomy & astrophysics
Abstract

Aims. We aim to identify bipolar Galactic H II regions and to understand their parental cloud structures, morphologies, evolution, and impact on the formation of new generations of stars. Methods. We use the Spitzer-GLIMPSE, Spitzer-MIPSGAL, and Herschel-Hi-GAL surveys to identify bipolar H II regions and to examine their morphologies. We search for their exciting star(s) using NIR data from the 2MASS, UKIDSS, and VISTA surveys. Massive molecular clumps are detected near these bipolar nebulae, and we estimate their temperatures, column densities, masses, and densities. We locate Class 0/I young stellar objects (YSOs) in their vicinities using the Spitzer and Herschel-PACS emission. Results. Numerical simulations suggest bipolar H II regions form and evolve in a two-dimensional flat- or sheet-like molecular cloud. We identified 16 bipolar nebulae in a zone of the Galactic plane between ℓ ± 60° and |b| < 1°. This small number, when compared with the 1377 bubble H II regions in the same area, suggests that most H II regions form and evolve in a three-dimensional medium. We present the catalogue of the 16 bipolar nebulae and a detailed investigation for six of these. Our results suggest that these regions formed in dense and flat structures that contain filaments. We find that bipolar H II regions have massive clumps in their surroundings. The most compact and massive clumps are always located at the waist of the bipolar nebula, adjacent to the ionised gas. These massive clumps are dense, with a mean density in the range of 105 cm−3 to several 106 cm−3 in their centres. Luminous Class 0/I sources of several thousand solar luminosities, many of which have associated maser emission, are embedded inside these clumps. We suggest that most, if not all, massive 0/I YSO formation has probably been triggered by the expansion of the central bipolar nebula, but the processes involved are still unknown. Modelling of such nebula is needed to understand the star formation processes at play.

Published
2018
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30. ALMA observations of RCW 120 Fragmentation at 0.01pc scale

Author

Leonardo Bronfman, Annie Zavagno, J. A. Rodón, M. Figueira, F. Louvet, N. Lo, Ricardo Finger, Laboratoire d'Astrophysique de Marseille (LAM), and Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Physics, H II region, 010504 meteorology & atmospheric sciences, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], Star formation, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, 01 natural sciences, Astrophysics - Astrophysics of Galaxies, Galaxy, Gravitation, Stars, photon-dominated region, Fragmentation (mass spectrometry), Space and Planetary Science, Ionization, Astrophysics of Galaxies (astro-ph.GA), 0103 physical sciences, Millimeter, H II regions, ISM: bubbles, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], 010303 astronomy & astrophysics, 0105 earth and related environmental sciences
Abstract

Little is known about how high-mass stars form. Around 30\% of the young high-mass stars in the Galaxy are observed at the edges of ionized (HII) regions. Therefore these are places of choice to study the earliest stages of high-mass star formation, especially towards the most massive condensations. High-spatial resolution observations in the millimeter range might reveal how these stars form and how they assemble their mass. We want to study the fragmentation process down to the 0.01~pc scale in the most massive condensation observed at the south-western edge of the HII region RCW~120 where the most massive Herschel cores ($\sim$124~$M_{\odot}$ in average) could form high-mass stars. Using ALMA 3~mm continuum observations towards the densest and most massive millimetric condensation (Condensation 1) of RCW~120, we used the getimages and getsources algorithms to extract the sources detected with ALMA and obtained their physical parameters. The fragmentation of the hersche cores is discussed through their Jeans mass to understand the properties of the future stars. We extracted 18 fragments from the ALMA continuum observation at 3~mm towards 8 cores detected with Herschel, whose mass and deconvolved size range from 2~$M_{\odot}$ to 32~$M_{\odot}$ and from 1.6~mpc to 28.8~mpc, respectively. The low degree of fragmentation observed, regarding to the thermal Jeans fragmentation, suggests that the observed fragmentation is inconsistent with ideal gravitational fragmentation and other ingredients such as turbulence or magnetic fields should be added in order to explain it. Finally, the range of fragments' mass indicates that the densest condensation of RCW~120 is a favourable place for the formation of high-mass stars with the presence of a probable UCHII region associated with the 27~$M_{\odot}$ Fragment 1 of Core 2., 7 pages, 4 figures

Published
2018
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31. High-mass Star Formation through Filamentary Collapse and Clump-fed Accretion in G22

Author

Simon Ellingsen, Jinghua Yuan, Christian Henkel, Annie Zavagno, Jin-Zeng Li, Yuefang Wu, Ke Wang, Hong-Li Liu, Zhiyuan Ren, Ya-Fang Huang, Tie Liu, Chinese Academy of Sciences [Beijing] (CAS), Peking University [Beijing], University of Tasmania [Hobart, Australia] (UTAS), Max-Planck-Institut für Radioastronomie (MPIFR), European Southern Observatory (ESO), Korea Astronomy and Space Science Institute (KASI), Okayama University, The Chinese University of Hong Kong [Hong Kong], Laboratoire d'Astrophysique de Marseille (LAM), and Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)

Subjects
010504 meteorology & atmospheric sciences, FOS: Physical sciences, Collapse (topology), Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Submillimeter Array, Spectral line, 0103 physical sciences, Protostar, Astrophysics::Solar and Stellar Astrophysics, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), ComputingMilieux_MISCELLANEOUS, Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences, Physics, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], Star formation, Astronomy and Astrophysics, Astrophysics - Astrophysics of Galaxies, Accretion (astrophysics), Stars, Astrophysics - Solar and Stellar Astrophysics, 13. Climate action, Space and Planetary Science, [SDU]Sciences of the Universe [physics], Astrophysics of Galaxies (astro-ph.GA), High mass, Astrophysics::Earth and Planetary Astrophysics
Abstract

How mass is accumulated from cloud-scale down to individual stars is a key open question in understanding high-mass star formation. Here, we present the mass accumulation process in a hub-filament cloud G22 which is composed of four supercritical filaments. Velocity gradients detected along three filaments indicate that they are collapsing with a total mass infall rate of about 440 $M_\odot$ Myr$^{-1}$, suggesting the hub mass would be doubled in six free-fall times, adding up to $ \sim2 $ Myr. A fraction of the masses in the central clumps C1 and C2 can be accounted for through large-scale filamentary collapse. Ubiquitous blue profiles in HCO$^+$ $ (3-2) $ and $^{13}$CO $ (3-2) $ spectra suggest a clump-scale collapse scenario in the most massive and densest clump C1. The estimated infall velocity and mass infall rate are 0.31 km s$^{-1}$ and $ 7.2 \times10^{-4} $ $M_\odot$ yr$^{-1}$, respectively. In clump C1, a hot molecular core (SMA1) is revealed by the SMA observations and an outflow-driving high-mass protostar is located at the center of SMA1. The mass of the protostar is estimated to be $ 11-15 $ $M_\odot$ and it is still growing with an accretion rate of $ 7\times10^{-5} $ $M_\odot$ yr$^{-1}$. The coexistent infall in filaments, clump C1, and the central hot core in G22 suggests that pre-assembled mass reservoirs (i.e., high-mass starless cores) may not be required to form high-mass stars. In the course of high-mass star formation, the central protostar, the core, and the clump can simultaneously grow in mass via core-fed/disk accretion, clump-fed accretion, and filamentary/cloud collapse., 17 pages, 16 figures 3 tables. and Accepted for publication in ApJ

Published
2017
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32. NGC 6334 and NGC 6357. Insights from spectroscopy of their OB star populations

Author

C. Adami, Annie Zavagno, Frédérique Motte, Jean-Claude Bouret, A. Herve, Quentin A. Parker, D. Russeil, Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, and Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES)

Subjects
Physics, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], OB star, 010308 nuclear & particles physics, Star formation, [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Molecular cloud, Astronomy, Flux, Astronomy and Astrophysics, Astrophysics, Stellar classification, 01 natural sciences, Spectral line, Hubble sequence, symbols.namesake, Stars, Space and Planetary Science, 0103 physical sciences, symbols, 010303 astronomy & astrophysics
Abstract

International audience; Aims. The formation of high‐mass stars is still debated. For this reason, several projects such as Herschel‐HOBYS are focussed on the study of the earliest phases of massive star formation. As a result, massive star‐forming complexes such as NGC 6334 and NGC 6357 have been observed in the far‐infrared to study their massive dense cores where massive stars are expected to form. However, to better characterise the environments of these cores we need to understand the previous massive star formation history. To better characterise the environment of these massive dense cores we study the previous high‐mass star formation and how these stars act on their environments. Methods. This study is based on the spectral classification of the OB stars identified towards NGC 6334 and NGC 6357 with spectra taken with the AAOmega spectrograph on the Anglo‐Australian Telescope (AAT). From the subsequent spectral classification of 109 stars across these regions we were able to evaluate the following: distance, age, mass, global star‐forming efficiency (SFE), and star formation rate (SFR) of the regions. The physical conditions of the ionised gas for both complexes was also derived. Results. We confirm that NGC 6334 and NGC 6357 belong to the Saggitarius‐Carina arm which, in this direction, extends from 1 kpc to 2.2 kpc. From the location of the stars in Hertzprung‐Russell diagram we show that stars older than similar to 10 Myr are broadly spread across these complexes, while younger stars are mainly located in the H II regions and stellar clusters. Our data also suggests that some of the young stars can be considered runaway stars. We evaluate a SFE of 0.019(‐0.007)(+0.008) and 0.021(‐0.003)(+0.004) and a SFR of 1.1 x 10(3) +/‐ 300 M‐circle dot Myr(‐1) and 1.7 x 10(3) +/‐ 400 M‐circle dot Myr(‐1) for NGC 6334 and NGC 6357, respectively. We note that 29 OB stars have X‐ray counterparts, most of them belonging to NGC 6357. This suggests that molecular clouds in NGC 6357 are more impacted by X‐ray flux and stellar winds than in NGC 6334. Finally, from the analysis of nebular lines (H alpha, [NII], and [SII]) from spectra from several regions of ionised gas, we confirm that the filaments in NGC 6357 are shock heated.

Published
2017
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33. Star formation towards the Galactic H II region RCW 120. Herschel observations of compact sources

Author

Figueira, M., Zavagno, Annie, Deharveng, L., Russeil, D., Anderson, D., Men’shchikov, A., Schneider, N., Hill, T., Motte, F., Mège, P., Leleu, G., Roussel, H., Bernard, P., Traficante, A., Paradis, D., Tigé, J., André, P., Bontemps, Sylvain, Abergel, A., Anderson, L. D., Men'Shchikov, A., Bernard, J.-P., Centro de Matemática e Aplicações Fundamentais (CMAF), Universidade de Lisboa (ULISBOA), Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Muséum national d'Histoire naturelle (MNHN), Department of Medicine - Halifax (DRA), Dalhousie University [Halifax], Département d'Astrophysique (ex SAP) (DAP), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7), Laboratory for Atmospheric and Space Physics [Boulder] (LASP), University of Colorado [Boulder], Sciences pour l'environnement (SPE), Centre National de la Recherche Scientifique (CNRS)-Université Pascal Paoli (UPP), Cassidian, EADS - European Aeronautic Defense and Space, École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL), Institut d'Astrophysique de Paris (IAP), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Institut de recherche en astrophysique et planétologie (IRAP), Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Laboratoire arc électrique et plasmas thermiques (LAEPT), Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP), FORMATION STELLAIRE 2017, Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut d'astrophysique spatiale (IAS), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), Université Pascal Paoli (UPP)-Centre National de la Recherche Scientifique (CNRS), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), Centro de Matemática e Aplicações Fundamentais ( CMAF ), Universidade de Lisboa ( ULISBOA ), Laboratoire d'Astrophysique de Marseille ( LAM ), Centre National de la Recherche Scientifique ( CNRS ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Aix Marseille Université ( AMU ) -Centre National d'Etudes Spatiales ( CNES ), Muséum National d'Histoire Naturelle ( MNHN ), Department of Medicine - Halifax ( DRA ), Département d'Astrophysique (ex SAP) ( DAP ), Institut de Recherches sur les lois Fondamentales de l'Univers ( IRFU ), Commissariat à l'énergie atomique et aux énergies alternatives ( CEA ) -Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives ( CEA ) -Université Paris-Saclay, Astrophysique Interactions Multi-échelles ( AIM - UMR 7158 - UMR E 9005 ), Commissariat à l'énergie atomique et aux énergies alternatives ( CEA ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ) -Université Paris Diderot - Paris 7 ( UPD7 ), Laboratory for Atmospheric and Space Physics [Boulder] ( LASP ), University of Colorado Boulder [Boulder], Sciences pour l'environnement ( SPE ), Université Pascal Paoli ( UPP ) -Centre National de la Recherche Scientifique ( CNRS ), École pratique des hautes études ( EPHE ), Institut d'Astrophysique de Paris ( IAP ), Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ), Institut de recherche en astrophysique et planétologie ( IRAP ), Université Paul Sabatier - Toulouse 3 ( UPS ) -Observatoire Midi-Pyrénées ( OMP ) -Centre National de la Recherche Scientifique ( CNRS ), Laboratoire arc électrique et plasmas thermiques ( LAEPT ), Centre National de la Recherche Scientifique ( CNRS ) -Université Blaise Pascal - Clermont-Ferrand 2 ( UBP ), Laboratoire d'Astrophysique de Bordeaux [Pessac] ( LAB ), Université de Bordeaux ( UB ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Bordeaux ( UB ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ), Institut d'astrophysique spatiale ( IAS ), Université Paris-Sud - Paris 11 ( UP11 ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ), Universidade de Lisboa = University of Lisbon (ULISBOA), Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), École Pratique des Hautes Études (EPHE), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Centre National de la Recherche Scientifique (CNRS), and Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES)

Subjects
Physics, stars: formation, 010308 nuclear & particles physics, Infrared, Star formation, Young stellar object, [ SDU.ASTR.GA ] Sciences of the Universe [physics]/Astrophysics [astro-ph]/Galactic Astrophysics [astro-ph.GA], Spectral density, Astronomy and Astrophysics, Astrophysics, 01 natural sciences, Stars, H ii regions, Far infrared, ISM: individual objects: RCW 120, 13. Climate action, Space and Planetary Science, 0103 physical sciences, Black-body radiation, [SDU.ASTR.GA]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Galactic Astrophysics [astro-ph.GA], 010303 astronomy & astrophysics, Envelope (waves)
Abstract

Context. The expansion of H ii regions can trigger the formation of stars. An overdensity of young stellar objects is observed at the edges of H ii regions but the mechanisms that give rise to this phenomenon are not clearly identified. Moreover, it is difficult to establish a causal link between H ii -region expansion and the star formation observed at the edges of these regions. A clear age gradient observed in the spatial distribution of young sources in the surrounding might be a strong argument in favor of triggering. Aims. We aim to characterize the star formation observed at the edges of H ii regions by studying the properties of young stars that form there. We aim to detect young sources, derive their properties and their evolution stage in order to discuss the possible causal link between the first-generation massive stars that form the H ii region and the young sources observed at their edges. Methods. We have observed the Galactic H ii region RCW 120 with Herschel PACS and SPIRE photometers at 70, 100, 160, 250, 350 and 500 μm. We produced temperature and H2 column density maps and use the getsources algorithm to detect compact sources and measure their fluxes at Herschel wavelengths. We have complemented these fluxes with existing infrared data. Fitting their spectral energy distributions with a modified blackbody model, we derived their envelope dust temperature and envelope mass. We computed their bolometric luminosities and discuss their evolutionary stages. Results. The overall temperatures of the region (without background subtraction) range from 15 K to 24 K. The warmest regions are observed towards the ionized gas. The coldest regions are observed outside the ionized gas and follow the emission of the cold material previously detected at 870 μm and 1.3 mm. The H2 column density map reveals the distribution of the cold medium to be organized in filaments and highly structured. Column densities range from 7 × 1021 cm-2 up to 9 × 1023 cm-2 without background subtraction. The cold regions observed outside the ionized gas are the densest and host star formation when the column density exceeds 2 × 1022 cm-2. The most reliable 35 compact sources are discussed. Using existing CO data and morphological arguments we show that these sources are likely to be associated with the RCW 120 region. These sources’ volume densities range from 2 × 105 cm-3 to 108 cm-3. Five sources have envelope masses larger than 50 M⊙ and are all observed in high column density regions (>7 × 1022 cm-2). We find that the evolutionary stage of the sources primarily depends on the density of their hosting condensation and is not correlated with the distance to the ionizing star. Conclusions. The Herschel data, with their unique sampling of the far infrared domain, have allowed us to characterize the properties of compact sources observed towards RCW 120 for the first time. We have also been able to determine the envelope temperature, envelope mass and evolutionary stage of these sources. Using these properties we have shown that the density of the condensations that host star formation is a key parameter of the star-formation history, irrespective of their projected distance to the ionizing stars.

Published
2017
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34. Herschel observations of the Galactic HII region RCW 79

Author

Alexander Men'shchikov, Yuefang Wu, Nicola Schneider, L. D. Anderson, D. Russeil, Annie Zavagno, Lise Deharveng, Frédérique Motte, Jinghua Yuan, M. Figueira, J. Tigé, Maohai Huang, Tracey Hill, Jin-Zeng Li, Hong-Li Liu, Laboratoire d'Astrophysique de Marseille (LAM), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), and Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)

Subjects
FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Luminosity, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Cosmic dust, Envelope (waves), Physics, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], 010308 nuclear & particles physics, Star formation, Diagram, Astronomy and Astrophysics, Astrophysics - Astrophysics of Galaxies, Stars, Astrophysics - Solar and Stellar Astrophysics, 13. Climate action, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), Log-normal distribution, Spectral energy distribution
Abstract

Triggered star formation around HII regions could be an important process. The Galactic HII region RCW 79 is a prototypical object for triggered high-mass star formation. We take advantage of Herschel data from the surveys HOBYS, "Evolution of Interstellar Dust", and Hi-Gal to extract compact sources in this region, complemented with archival 2MASS, Spitzer, and WISE data to determine the physical parameters of the sources (e.g., envelope mass, dust temperature, and luminosity) by fitting the spectral energy distribution. We obtained a sample of 50 compact sources, 96% of which are situated in the ionization-compressed layer of cold and dense gas that is characterized by the column density PDF with a double-peaked lognormal distribution. The 50 sources have sizes of 0.1-0.4 pc with a typical value of 0.2 pc, temperatures of 11-26 K, envelope masses of 6-760 $M_\odot$, densities of 0.1-44 $\times$ $10^5$ cm$^{-3}$, and luminosities of 19-12712 $L_\odot$. The sources are classified into 16 class 0, 19 intermediate, and 15 class I objects. Their distribution follows the evolutionary tracks in the diagram of bolometric luminosity versus envelope mass (Lbol-Menv) well. A mass threshold of 140 $M_\odot$, determined from the Lbol-Menv diagram, yields 12 candidate massive dense cores that may form high-mass stars. The core formation efficiency (CFE) for the 8 massive condensations shows an increasing trend of the CFE with density. This suggests that the denser the condensation, the higher the fraction of its mass transformation into dense cores, as previously observed in other high-mass star-forming regions., Accepted by A&A on 17 January 2017

Published
2017
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35. High‐mass Starless Clumps in the Inner Galactic Plane: The Sample and Dust Properties

Author

Neal J. Evans, Hong-Li Liu, Ke Wang, Jinghua Yuan, Annie Zavagno, Tie Liu, Christian Henkel, Simon Ellingsen, Yuefang Wu, Jin-Zeng Li, Laboratoire d'Astrophysique de Marseille (LAM), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), and Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Infrared, FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, 01 natural sciences, law.invention, law, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Maser, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics, Physics, Spiral galaxy, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], 010308 nuclear & particles physics, Star formation, Galactic Center, Astronomy and Astrophysics, Galactic plane, Astrophysics - Astrophysics of Galaxies, Stars, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), High mass
Abstract

We report a sample of 463 high-mass starless clump (HMSC) candidates within $-60\deg0.08$ g cm$^{-2}$ could be possible high-mass starless cores. Further investigations toward these HMSCs would undoubtedly shed light on comprehensively understanding the birth of high-mass stars., Comment: 16 pages, 15 figures, and 5 tables. Accepted for publication in ApJS. FITS images for the far-IR to sub-mm data, H2 column density and dust temperature maps of all the HMSC candidates are available at https: //yuanjinghua.github.io/hmscs.html. Codes used for this work are publicly available from https://github.com/yuanjinghua/HMSCs_cat

Published
2017
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36. The earliest phases of high-mass star formation, as seen in NGC 6334 by Herschel-HOBYS

Author

Pierre Didelon, L. D. Anderson, Sergio Molinari, Doris Arzoumanian, Stefano Pezzuto, Nicola Schneider, Jason M. Kirk, Q. Nguyen Luong, Vincent Minier, G. Leuleu, J. Di Francesco, F. Louvet, Pierrick Martin, M. Benedettini, K. L. J. Rygl, Annie Zavagno, D. Russeil, T. Rayner, J. Bardagi, D. Polychroni, T. Nony, Ph. André, M. Figueira, Tracey Hill, J.-P. Bernard, P. Persi, Davide Elia, Vera Konyves, A. Rivera-Ingraham, G. J. White, H. Roussel, Luigi Spinoglio, J. Tigé, Sylvain Bontemps, M. Hennemann, Frédérique Motte, Sciences pour l'environnement (SPE), Université Pascal Paoli (UPP)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Laboratory for Atmospheric and Space Physics [Boulder] (LASP), University of Colorado [Boulder], Herzberg Institute of Astrophysics, National Research Council of Canada (NRC), FORMATION STELLAIRE 2017, Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut d'astrophysique spatiale (IAS), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Istituto di Astrofisica e Planetologia Spaziali - INAF (IAPS), Istituto Nazionale di Astrofisica (INAF), Centro de Matemática e Aplicações Fundamentais (CMAF), Universidade de Lisboa = University of Lisbon (ULISBOA), Istituto di Fisica dello Spazio Interplanetario (IFSI), National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), Faculty of Informatics [Lugano], Università della Svizzera italiana = University of Italian Switzerland (USI), School of Physics and Astronomy [Cardiff], Cardiff University, Institut d'Astrophysique de Paris (IAP), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Antarctic Research a European Network for Astrophysics (ARENA), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Engineering Department, University of Cambridge [UK] (CAM), Centre National de la Recherche Scientifique (CNRS)-Université Pascal Paoli (UPP), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Universidade de Lisboa (ULISBOA), Consiglio Nazionale delle Ricerche (CNR), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), ITA, GBR, FRA, and CAN

Subjects
Physics, stars: formation, 010504 meteorology & atmospheric sciences, stars: protostars, Star formation, extinction, Molecular cloud, Astronomy and Astrophysics, Astrophysics, 01 natural sciences, ISM: clouds, Spire, ISM: individual objects: NGC 6334, Space and Planetary Science, 0103 physical sciences, High mass, Protostar, submillimeter: ISM, Millimeter, dust, extinction, dust, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], 010303 astronomy & astrophysics, 0105 earth and related environmental sciences
Abstract

Aims: To constrain models of high-mass star formation, the Herschel-HOBYS key program aims at discovering massive dense cores (MDCs) able to host the high-mass analogs of low-mass prestellar cores, which have been searched for over the past decade. We here focus on NGC 6334, one of the best-studied HOBYS molecular cloud complexes. Methods: We used Herschel/PACS and SPIRE 70-500 μm images of the NGC 6334 complex complemented with (sub)millimeter and mid-infrared data. We built a complete procedure to extract 0.1 pc dense cores with the getsources software, which simultaneously measures their far-infrared to millimeter fluxes. We carefully estimated the temperatures and masses of these dense cores from their spectral energy distributions (SEDs). We also identified the densest pc-scale cloud structures of NGC 6334, one 2 pc × 1 pc ridge and two 0.8 pc × 0.8 pc hubs, with volume-averaged densities of 105 cm-3. Results: A cross-correlation with high-mass star formation signposts suggests a mass threshold of 75 M☉ for MDCs in NGC 6334. MDCs have temperatures of 9.5-40 K, masses of 75-1000 M☉, and densities of 1 × 105-7 × 107 cm-3. Their mid-infrared emission is used to separate 6 IR-bright and 10 IR-quiet protostellar MDCs while their 70 μm emission strength, with respect to fitted SEDs, helps identify 16 starless MDC candidates. The ability of the latter to host high-mass prestellar cores is investigated here and remains questionable. An increase in mass and density from the starless to the IR-quiet and IR-bright phases suggests that the protostars and MDCs simultaneously grow in mass. The statistical lifetimes of the high-mass prestellar and protostellar core phases, estimated to be 1-7 × 104 yr and at most 3 × 105 yr respectively, suggest a dynamical scenario of high-mass star formation. Conclusions: The present study provides good mass estimates for a statistically significant sample, covering the earliest phases of high-mass star formation. High-mass prestellar cores may not exist in NGC 6334, favoring a scenario presented here, which simultaneously forms clouds, ridges, MDCs, and high-mass protostars. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA. Catalogs built from Tables A.1-A.12, are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/602/A77

Published
2017
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37. The Hi-GAL catalogue of dusty filamentary structures in the Galactic plane.

Author

Schisano, Eugenio, Molinari, S, Elia, D, Benedettini, M, Olmi, L, Pezzuto, S, Traficante, A, Brescia, M, Cavuoti, S, di Giorgio, A M, Liu, S J, Moore, T J T, Noriega-Crespo, A, Riccio, G, Baldeschi, A, Becciani, U, Peretto, N, Merello, M, Vitello, F, and Zavagno, A

Subjects
MOLECULAR clouds, MILKY Way, STAR formation, CATALOGS, FIBERS
Abstract

The recent data collected by Herschel have confirmed that interstellar structures with a filamentary shape are ubiquitously present in the Milky Way. Filaments are thought to be formed by several physical mechanisms acting from large Galactic scales down to subparsec fractions of molecular clouds, and they might represent a possible link between star formation and the large-scale structure of the Galaxy. In order to study this potential link, a statistically significant sample of filaments spread throughout the Galaxy is required. In this work, we present the first catalogue of 32 059 candidate filaments automatically identified in the Herschel Infrared Galactic plane Survey (Hi-GAL) of the entire Galactic plane. For these objects, we determined morphological (length l a and geometrical shape) and physical (average column density |$N_{\rm H_{2}}$| and average temperature T) properties. We identified filaments with a wide range of properties: 2 ≤ l a ≤ 100 arcmin, |$10^{20} \le N_{\rm H_{2}} \le 10^{23}$|  cm−2 and 10 ≤ T ≤ 35 K. We discuss their association with the Hi-GAL compact sources, finding that the most tenuous (and stable) structures do not host any major condensation. We also assign a distance to ∼18 400 filaments, for which we determine mass, physical size, stability conditions and Galactic distribution. When compared with the spiral arms structure, we find no significant difference between the physical properties of on-arm and inter-arm filaments. We compare our sample with previous studies, finding that our Hi-GAL filament catalogue represents a significant extension in terms of Galactic coverage and sensitivity. This catalogue represents a unique and important tool for future studies devoted to understanding the filament life-cycle. [ABSTRACT FROM AUTHOR]

Published
2020
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38. Characterizing filaments in regions of high-mass star formation: High-resolution submilimeter imaging of the massive star-forming complex NGC 6334 with ArT\'eMiS

Author

V. Revéret, L. Rodriguez, J. Martignac, Michel Lortholary, Cyrille Delisle, Frédérique Motte, Didier Dubreuil, Doris Arzoumanian, P. Palmeirim, Eric Doumayrou, J. Le Pennec, François Visticot, H. Roussel, Tracey Hill, D. Russeil, Annie Zavagno, C. De Breuck, Nicola Schneider, A. Roy, Nicolas Peretto, Y. Shimajiri, Sylvain Bontemps, J. Tigé, Pascal Gallais, M. Hennemann, Vincent Minier, M. Talvard, Vera Konyves, Ph. André, Luc Dumaye, K. L. J. Rygl, Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7), Institut d'astrophysique spatiale (IAS), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut d'Astrophysique de Paris (IAP), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Centre National de la Recherche Scientifique (CNRS), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Laboratoire de Synthèse Organique (Hétérochimie organique, organoéléments et matériaux) (LSOHOOM), Université de Nantes (UN)-Centre National de la Recherche Scientifique (CNRS), Département d'Astrophysique, de physique des Particules, de physique Nucléaire et de l'Instrumentation Associée (DAPNIA), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Procédés, Matériaux et Energie Solaire (PROMES), Université de Perpignan Via Domitia (UPVD)-Centre National de la Recherche Scientifique (CNRS), FORMATION STELLAIRE 2016, Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Astrophysique de Marseille (LAM), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), DAM Île-de-France (DAM/DIF), Direction des Applications Militaires (DAM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Département d'Astrophysique (ex SAP) (DAP), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Department of Mechanical Engineering, University of Bristol [Bristol], Toyota Technological Institute at Chicago [Chicago] (TTIC), Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), École normale supérieure - Paris (ENS-PSL), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Centre National de la Recherche Scientifique (CNRS), École normale supérieure - Paris (ENS Paris)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and PSL Research University (PSL)-PSL Research University (PSL)-Université de Cergy Pontoise (UCP)

Subjects
010504 meteorology & atmospheric sciences, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, law.invention, Telescope, Gravitation, Protein filament, law, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences, QB, Physics, Star formation, Molecular cloud, Bolometer, Astronomy and Astrophysics, Astrophysics - Astrophysics of Galaxies, Interstellar medium, Stars, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), Astrophysics::Earth and Planetary Astrophysics, [SDU.ASTR.GA]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Galactic Astrophysics [astro-ph.GA]
Abstract

Herschel observations of nearby molecular clouds suggest that interstellar filaments and prestellar cores represent two fundamental steps in the star formation process. The observations support a picture of low-mass star formation according to which ~ 0.1 pc-wide filaments form first in the cold interstellar medium, probably as a result of large-scale compression of interstellar matter by supersonic turbulent flows, and then prestellar cores arise from gravitational fragmentation of the densest filaments. Whether this scenario also applies to regions of high-mass star formation is an open question, in part because Herschel data cannot resolve the inner width of filaments in the nearest regions of massive star formation. We used the bolometer camera ArTeMiS on the APEX telescope to map the central part of the NGC6334 complex at a factor of > 3 higher resolution than Herschel at 350 microns. Combining ArTeMiS data with Herschel data allowed us to study the structure of the main filament of the complex with a resolution of 8" or < 0.07 pc at d ~ 1.7 kpc. Our study confirms that this filament is a very dense, massive linear structure with a line mass ranging from ~ 500 Msun/pc to ~ 2000 Msun/pc over nearly 10 pc. It also demonstrates that its inner width remains as narrow as W ~ 0.15 +- 0.05 pc all along the filament length, within a factor of < 2 of the characteristic 0.1 pc value found with Herschel for lower-mass filaments in the Gould Belt. While it is not completely clear whether the NGC 6334 filament will form massive stars or not in the future, it is two to three orders of magnitude denser than the majority of filaments observed in Gould Belt clouds, and yet has a very similar inner width. This points to a common physical mechanism for setting the filament width and suggests that some important structural properties of nearby clouds also hold in high-mass star forming regions., 10 pages, 6 figures. A&A, in press

Published
2016
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39. Interactions of the Infrared bubble N4 with the surroundings

Author

Gloria Mabel Dubner, Sergio Molinari, Yuefang Wu, Jin-Zeng Li, Hong-Li Liu, M. E. Ortega, Si Ju Zhang, Sergio Ariel Paron, Ya Fang Huang, Maohai Huang, Jinghua Yuan, Tie Liu, Annie Zavagno, Manash R. Samal, Department of Plant Biology [Carnegie] (DPB), Carnegie Institution for Science, Instituto de Astronomía y Física del Espacio [Buenos Aires] (IAFE), Consejo Nacional de Investigaciones Científicas y Técnicas [Buenos Aires] (CONICET)-Universidad de Buenos Aires [Buenos Aires] (UBA), Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Carnegie Institution for Science [Washington], and Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES)

Subjects
H II region, Hydrogen, Infrared, Ciencias Físicas, Bubble, chemistry.chemical_element, FOS: Physical sciences, Astrophysics, 01 natural sciences, 0103 physical sciences, 010303 astronomy & astrophysics, Cosmic dust, Physics, formation [stars], 010308 nuclear & particles physics, Star formation, Astronomy and Astrophysics, Astrophysics - Astrophysics of Galaxies, bubbles [ISM], Astronomía, Wavelength, Stars, chemistry, 13. Climate action, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), HII regions [ISM], [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], CIENCIAS NATURALES Y EXACTAS
Abstract

The physical mechanisms that induce the transformation of a certain mass of gas in new stars are far from being well understood. Infrared bubbles associated with HII regions have been considered to be good samples of investigating triggered star formation. In this paper we report on the investigation of the dust properties of the infrared bubble N4 around the HII region G11.898+0.747, analyzing its interaction with its surroundings and star formation histories therein, with the aim of determining the possibility of star formation triggered by the expansion of the bubble. Using Herschel PACS and SPIRE images with a wide wavelength coverage, we reveal the dust properties over the entire bubble. Meanwhile, we are able to identify six dust clumps surrounding the bubble, with a mean size of 0.50 pc, temperature of about 22 K, mean column density of 1.7 $\times10^{22}$ cm$^{-2}$, mean volume density of about 4.4 $\times10^{4}$ cm$^{-3}$, and a mean mass of 320 $M_{\odot}$. In addition, from PAH emission seen at 8 $\mu$m, free-free emission detected at 20 cm and a probability density function in special regions, we could identify clear signatures of the influence of the HII region on the surroundings. There are hints of star formation, though further investigation is required to demonstrate that N4 is the triggering source., Comment: Accepted by ApJ (16 pages, 11 figures, 9 tables)

Published
2016
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40. Observations of star formation triggered by H <scp>ii</scp> regions

Author

Annie Zavagno and Lise Deharveng

Subjects
Physics, Space and Planetary Science, Star formation, Astronomy, Astronomy and Astrophysics, Galaxy
Abstract

Observations show that expanding H ii regions may trigger star formation. We discuss several aspects of this type of star formation, and try to estimate its prevalence. We show how LMC H ii regions may help us to understand what we see in our Galaxy.

Published
2010
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41. ATLASGAL – The APEX telescope large area survey of the galaxy at 870 $\mathsf{\mu}$m

Author

Thomas Henning, Peter Schilke, Bertrand Lefloch, Ernst Kreysa, Christophe Risacher, Diego Mardones, V. Revéret, Hendrik Linz, Achim Weiss, L. Deharveng, Giorgio Siringo, Frédérique Motte, D. Russeil, Sergio Molinari, Henrik Beuther, Leonardo Testi, Leonardo Bronfman, Friedrich Wyrowski, M. Wienen, R. Cesaroni, Annie Zavagno, Fabrice Herpin, Guido Garay, Attila Kovács, Karl M. Menten, Sylvain Bontemps, Frederic Schuller, T. Vasyunina, Yanett Contreras, Vincent Minier, C. M. Walmsley, T. Troost, L. A. Nyman, and Nicola Schneider

Subjects
Physics, 010504 meteorology & atmospheric sciences, Star formation, Milky Way, Extinction (astronomy), Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Galactic plane, 01 natural sciences, Galaxy, Interstellar medium, Star cluster, Space and Planetary Science, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Protostar, Astrophysics::Earth and Planetary Astrophysics, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences
Abstract

(Abridged) Studying continuum emission from interstellar dust is essential to locate and characterize the highest density regions in the interstellar medium. In particular, the early stages of massive star formation are still mysterious. Our goal is to produce a large scale, systematic database of massive pre- and proto-stellar clumps in the Galaxy, in order to better understand how and under what conditions star formation takes place. A well characterized sample of star-forming sites will deliver an evolutionary sequence and a mass function of high-mass star-forming clumps. Such a systematic survey at submm wavelengths also represents a pioneering work in preparation for Herschel and ALMA. The APEX telescope is ideally located to observe the inner Milky Way. The recently commissioned Large APEX Bolometer Camera (LABOCA) is a 295-element bolometer array observing at 870 microns, with a beam of 19". Taking advantage of its large field of view (11.4') and excellent sensitivity, we have started an unbiased survey of the Galactic Plane, with a noise level of 50-70 mJy/beam: the APEX Telescope Large Area Survey of the Galaxy (ATLASGAL). As a first step, we have covered 95 sq. deg. These data reveal 6000 compact sources brighter than 0.25 Jy, as well as extended structures, many of them filamentary. About two thirds of the compact sources have no bright infrared counterpart, and some of them are likely to correspond to the precursors of (high-mass) proto-stars or proto-clusters. Other compact sources harbor hot cores, compact HII regions or young embedded clusters. Assuming a typical distance of 5 kpc, most sources are clumps smaller than 1 pc with masses from a few 10 to a few 100 M_sun. In this introductory paper, we show preliminary results from these ongoing observations, and discuss the perspectives of the survey.

Published
2009
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42. Bipolar H II regions - Morphology and star formation in their vicinity I. G319.88+00.79 and G010.32-00.15

Author

James M. Jackson, Lise Deharveng, Manash R. Samal, Annie Zavagno, M. R. Pestalozzi, Jill Rathborne, D. Brevot, G. Leleu, Sergio Molinari, Jonathan B. Foster, L. D. Anderson, Ana Duarte-Cabral, Laboratoire d'Astrophysique de Marseille ( LAM ), Centre National de la Recherche Scientifique ( CNRS ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Aix Marseille Université ( AMU ) -Centre National d'Etudes Spatiales ( CNES ), National Radio Astronomy Observatory [Green Bank] ( NRAO ), National Radio Astronomy Observatory ( NRAO ), Department of Physics and Astronomy [Morgantown], West Virginia University [Morgantown], Laboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux ( L3AB ), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ), Université Sciences et Technologies - Bordeaux 1, FORMATION STELLAIRE 2014, Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ) -Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ) -Observatoire aquitain des sciences de l'univers ( OASU ), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ) -Centre National de la Recherche Scientifique ( CNRS ) -Laboratoire d'Astrophysique de Bordeaux [Pessac] ( LAB ), Université de Bordeaux ( UB ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Bordeaux ( UB ), Observatoire aquitain des sciences de l'univers ( OASU ), Laboratoire d'Astrophysique de Bordeaux [Pessac] ( LAB ), Université de Bordeaux ( UB ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ), INAF - Osservatorio Astronomico di Roma ( OAR ), Istituto Nazionale di Astrofisica ( INAF ), Laboratoire d'Astrophysique de Marseille (LAM), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), National Radio Astronomy Observatory [Green Bank] (NRAO), National Radio Astronomy Observatory (NRAO), Laboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux (L3AB), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Bordeaux (UB), Observatoire aquitain des sciences de l'univers (OASU), Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), INAF - Osservatorio Astronomico di Roma (OAR), Istituto Nazionale di Astrofisica (INAF), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Université Sciences et Technologies - Bordeaux 1 (UB), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Observatoire aquitain des sciences de l'univers (OASU), and Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB)

Subjects
Physics, Solar mass, H II region, Star formation, Young stellar object, [ PHYS.ASTR ] Physics [physics]/Astrophysics [astro-ph], Extinction (astronomy), FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Astrophysics - Astrophysics of Galaxies, law.invention, Stars, 13. Climate action, Space and Planetary Science, law, Astrophysics of Galaxies (astro-ph.GA), Ionization, Maser, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

Our goal is to identify bipolar HII regions and to understand their morphology, their evolution, and the role they play in the formation of new generations of stars. We use the Spitzer and Herschel Hi-GAL surveys to identify bipolar HII regions. We search for their exciting star(s) and estimate their distances using near-IR data. Dense clumps are detected using Herschel-SPIRE data. MALT90 observations allow us to ascertain their association with the central HII region. We identify Class 0/I YSOs using their Spitzer and Herschel-PACS emissions. These methods will be applied to the entire sample of candidate bipolar HII regions. This paper focuses on two bipolar HII regions, one interesting in terms of its morphology, G319.88$+$00.79, and one in terms of its star formation, G010.32$-$00.15. Their exciting clusters are identified and their photometric distances estimated to be 2.6 kpc and 1.75 kpc, respectively. We suggest that these regions formed in dense and flat structures that contain filaments. They have a central ionized region and ionized lobes perpendicular to the parental cloud. The remains of the parental cloud appear as dense (more than 10^4 per cm^3) and cold (14-17 K) condensations. The dust in the PDR is warm (19-25 K). Dense massive clumps are present around the central ionized region. G010.32-00.14 is especially remarkable because five clumps of several hundred solar masses surround the central HII region; their peak column density is a few 10^23 per cm^2, and the mean density in their central regions reaches several 10^5 per cm^3. Four of them contain at least one massive YSO; these clumps also contain extended green objects and Class II methanol masers. This morphology suggests that the formation of a second generation of massive stars has been triggered by the central bipolar HII region. It occurs in the compressed material of the parental cloud., 32 pages, 28 figures, to be published in A&A

Published
2015
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43. Herschel Observations of the W3 GMC (II): Clues to the Formation of Clusters of High-Mass Stars

Author

A. Marston, K. L. J. Rygl, Tracey Hill, D. Polychroni, M. Hennemann, Luigi Spinoglio, Frédérique Motte, Stefano Pezzuto, Cassandra Fallscheer, Nicola Schneider, Alexander Men'shchikov, Vera Konyves, G. J. White, Annie Zavagno, A. Rivera-Ingraham, Pierrick Martin, Ph. André, Sylvain Bontemps, J. Di Francesco, Q. Nguyen Luong, J.-Ph. Bernard, Department of Applied Mathematics and Statistics, Colorado School of Mines, FORMATION STELLAIRE 2015, Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7), Laboratoire d'Astrophysique de Marseille (LAM), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), SLAC National Accelerator Laboratory (SLAC), Stanford University, Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Stanford Linear Accelerator Center (SLAC), and Stanford University [Stanford]

Subjects
Physics, Stellar population, 010308 nuclear & particles physics, Star formation, [SDU.ASTR.CO]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO], Extinction (astronomy), FOS: Physical sciences, Astronomy and Astrophysics, Probability density function, Function (mathematics), Astrophysics, 01 natural sciences, Constructive, Astrophysics - Astrophysics of Galaxies, Stars, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), 0103 physical sciences, Log-normal distribution, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics
Abstract

The W3 GMC is a prime target for investigating the formation of high-mass stars and clusters. This second study of W3 within the HOBYS Key Program provides a comparative analysis of subfields within W3 to further constrain the processes leading to the observed structures and stellar population. Probability density functions (PDFs) and cumulative mass distributions (CMDs) were created from dust column density maps, quantified as extinction Av. The shape of the PDF, typically represented with a lognormal function at low Av "breaking" to a power-law tail at high Av, is influenced by various processes including turbulence and self-gravity. The breaks can also be identified, often more readily, in the CMDs. The PDF break from lognormal (Av(SF)= 6-10 mag) appears to shift to higher Av by stellar feedback, so that high-mass star-forming regions tend to have higher PDF breaks. A second break at Av > 50 mag traces structures formed or influenced by a dynamic process. Because such a process has been suggested to drive high-mass star formation in W3, this second break might then identify regions with potential for hosting high-mass stars/clusters. Stellar feedback appears to be a major mechanism driving the local evolution and state of regions within W3. A high initial star formation efficiency in a dense medium could result in a self-enhancing process, leading to more compression and favourable star-formation conditions (e.g., colliding flows), a richer stellar content, and massive stars. This scenario would be compatible with the "convergent constructive feedback" model introduced in our previous Herschel study., Accepted for publication in the Astrophysical Journal

Published
2015
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44. Star formation in the filament of S254-S258 OB complex: a cluster in the process of making

Author

Samal, M. R., Ojha, D. K., Jose, J., Zavagno, Annie, Takahashi, S., Neichel, B., Kim, J. S., Chauhan, N., Pandey, A. K., Zinchenko, I., Tamura, M., Ghosh, S. K., Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Tata Institute for Fundamental Research (TIFR), Kavli Institute for Astronomy and Astrophysics [Beijing] (KIAA-PKU), Peking University [Beijing], Joint ALMA Observatory (JAO), European Southern Observatory (ESO)-National Radio Astronomy Observatory (NRAO), Steward Observatory, University of Arizona, Institute of Astronomy [Taiwan] (IANCU), National Central University [Taiwan] (NCU), Aryabhatta Research Institute of Observational Sciences, Aryabhatta Research Institute of Observational Sciences (ARIES), Institute of Applied Physics of RAS, Russian Academy of Sciences [Moscow] (RAS), National Astronomical Observatory of Japan (NAOJ), and National Centre for Radio Astrophysics [Pune] (NCRA)

Subjects
filament, Astrophysics of Galaxies (astro-ph.GA), infrared, individual: S254-S258 complex, FOS: Physical sciences, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Astrophysics - Astrophysics of Galaxies, young stellar objects, Astrophysics::Galaxy Astrophysics, star formation, dark cloud
Abstract

Infrared Dark Clouds are ideal laboratories to study the initial processes of high-mass star and star cluster formation. We investigated star formation activity of an unexplored filamentary dark cloud (~5.7pc x 1.9pc), which itself is part of a large filament (~20pc) located in the S254-S258 OB complex at a distance of 2.5kpc. Using MIPS Spitzer 24 micron data, we uncover 49 sources with SNR greater than 5. We identified 45 sources as candidate YSOs of Class I, Flat-spectrum & Class II nature. Additional 17 candidate YSOs (9 Class I & 8 Class II) are also identified using JHK and WISE photometry. We find that the protostar to Class II sources ratio (~2) and the protostar fraction (~70%) of the region are high. When the protostar fraction compared to other young clusters, it suggests that the star formation in the dark cloud was possibly started only 1 Myr ago. Combining the NIR photometry of the YSO candidates with the theoretical evolutionary models, we infer that most of the candidate YSOs formed in the dark cloud are low-mass (, 14 pages, 9 figures, Accepted by Astronomy & Astrophysics

Published
2015
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45. Deep near-infrared adaptive optics observations of a young embedded cluster at the edge of the RCW 41 HII region

Author

Manash R. Samal, Annie Zavagno, A. Bernard, Henri Plana, Benoit Neichel, Thierry Fusco, Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Plateforme d'Imagerie Multimodale LyonTech (PILoT), Centre de Recherche en Acquisition et Traitement de l'Image pour la Santé (CREATIS), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Jean Monnet - Saint-Étienne (UJM)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Jean Monnet - Saint-Étienne (UJM)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), ONERA - The French Aerospace Lab [Châtillon], ONERA-Université Paris Saclay (COmUE), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), Université Jean Monnet [Saint-Étienne] (UJM)-Hospices Civils de Lyon (HCL)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Université Jean Monnet [Saint-Étienne] (UJM)-Hospices Civils de Lyon (HCL)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), and Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM)

Subjects
Physics, H II region, Initial mass function, Mass distribution, Star formation, Young stellar object, Brown dwarf, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Photometry (optics), Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Chamaeleon, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Astrophysics - Instrumentation and Methods for Astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), Solar and Stellar Astrophysics (astro-ph.SR)
Abstract

We investigate the star formation activity in a young star forming cluster embedded at the edge of the RCW 41 HII region. As a complementary goal, we aim at demonstrating the gain provided by Wide-Field Adaptive Optics instruments to study young clusters. We used deep, JHKs images from the newly commissioned Gemini-GeMS/GSAOI instrument, complemented with Spitzer IRAC observations, in order to study the photometric properties of the young stellar cluster. GeMS is an AO instrument, delivering almost diffraction limited images over a field of 2' across. The exquisite angular resolution allows us to reach a limiting magnitude of J = 22 for 98% completeness. The combination of the IRAC photometry with our JHKs catalog is used to build color-color diagrams, and select Young Stellar Objects (YSOs) candidates. We detect the presence of 80 Young Stellar Object (YSO) candidates. Those YSOs are used to infer the cluster age, which is found to be in the range 1 to 5 Myr. We find that 1/3 of the YSOs are in a range between 3 to 5 Myr, while 2/3 of the YSO are < 3 Myr. When looking at the spatial distribution of these two populations, we evidence a potential age gradient across the field, suggesting sequential star formation. We construct the IMF, and show that we can sample the mass distribution well into the brown dwarf regime (down to 0.01 Msun). The logarithmic mass function rises to peak at 0.3 Msun, before turning over and declining into the brown dwarf regime. The total cluster mass derived is estimated to be 78 +/- 18 Msun, while the ratio of brown dwarfs to star derived is 18 p/- 5 %. When comparing with other young clusters, we find that the IMF shape of the young cluster embedded within RCW 41 is consistent with those of Trapezium, IC 348 or Chamaeleon I, except for the IMF peak, which happens to be at higher mass. This characteristic is also seen in clusters like NGC 6611 or even Taurus., 19 pages, 17 figures, Accepted for publication in A&A, V2 with editor corrections

Published
2015
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46. Galactic Cold Cores IV. Cold sub-millimetre sources: catalogue and statistical analysis

Author

Gábor Marton, Annie Zavagno, Frédérique Motte, P. M. McGehee, Laurent Pagani, I. Ristorcelli, D. J. Marshall, Mika Juvela, Nathalie Ysard, V.-M. Pelkonen, L. V. Tóth, J.-P. Bernard, Sarolta Zahorecz, J. Malinen, Roberta Paladini, E. Falgarone, L. Montier, J. Montillaud, A. Rivera-Ingraham, Yasuo Doi, Univers, Transport, Interfaces, Nanostructures, Atmosphère et environnement, Molécules (UMR 6213) (UTINAM), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), Institut de recherche en astrophysique et planétologie (IRAP), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), TKK Helsinki University of Technology (TKK), Département d'Astrophysique (ex SAP) (DAP), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Centre National de la Recherche Scientifique (CNRS), Eötvös Loránd University (ELTE), European Southern Observatory (ESO), Institut d'astrophysique spatiale (IAS), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Infrared Processing and Analysis Center (IPAC), California Institute of Technology (CALTECH), Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7), École normale supérieure - Paris (ENS Paris)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université de Cergy Pontoise (UCP), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), École normale supérieure - Paris (ENS Paris), and Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES)

Subjects
Physics, education.field_of_study, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], Star formation, Interstellar cloud, Population, Astronomy, Astronomy and Astrophysics, Context (language use), Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Radiation, Color temperature, 7. Clean energy, Spire, symbols.namesake, 13. Climate action, Space and Planetary Science, symbols, Planck, education, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Astrophysics::Galaxy Astrophysics
Abstract

Context. For the project Galactic cold cores, Herschel photometric observations were carried out as a follow-up of cold regions of interstellar clouds previously identified with the Planck satellite. The aim of the project is to derive the physical properties of the population of cold sources and to study its connection to ongoing and future star formation. Aims. We build a catalogue of cold sources within the clouds in 116 fields observed with the Herschel PACS and SPIRE instruments. We wish to determine the general physical characteristics of the cold sources and to examine the correlations with their host cloud properties. Methods. From Herschel data, we computed colour temperature and column density maps of the fields. We estimated the distance to the target clouds and provide both uncertainties and reliability flags for the distances. The getsources multiwavelength source extraction algorithm was employed to build a catalogue of several thousand cold sources. Mid-infrared data were used, along with colour and position criteria, to separate starless and protostellar sources. We also propose another classification method based on submillimetre temperature profiles. We analysed the statistical distributions of the physical properties of the source samples. Results. We provide a catalogue of ~4000 cold sources within or near star forming clouds, most of which are located either in nearby molecular complexes (≲1 kpc) or in star forming regions of the nearby galactic arms (~2 kpc). About 70% of the sources have a size compatible with an individual core, and 35% of those sources are likely to be gravitationally bound. Significant statistical differences in physical properties are found between starless and protostellar sources, in column density versus dust temperature, mass versus size, and mass versus dust temperature diagrams. The core mass functions are very similar to those previously reported for other regions. On statistical grounds we find that gravitationally bound sources have higher background column densities (median N_(bg)(H_2) ~ 5 × 10^(21) cm^(-2)) than unbound sources (median N_(bg)(H_2) ~ 3 × 10^(21) cm^(-2)). These values of N_(bg)(H_2) are higher for higher dust temperatures of the external layers of the parent cloud. However, only in a few cases do we find clear N_(bg)(H_2) thresholds for the presence of cores. The dust temperatures of cloud external layers show clear variations with galactic location, as may the source temperatures. Conclusions. Our data support a more complex view of star formation than in the simple idea of a column density threshold. They show a clear influence of the surrounding UV-visible radiation on how cores distribute in their host clouds with possible variations on the Galactic scale.

Published
2015
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47. $Herschel$ SPIRE-FTS observations of RCW 120

Author

Alain Abergel, F. Le Petit, J.-P. Baluteau, J. A. Rodón, M. Köhler, Annie Zavagno, Emilie Habart, J. Le Bourlot, European Southern Observatory, Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Institut d'astrophysique spatiale (IAS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Laboratoire Univers et Théories (LUTH (UMR_8102)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Physics, H II region, Star formation, Young stellar object, Continuum (design consultancy), FOS: Physical sciences, Astronomy and Astrophysics, Context (language use), Astrophysics, Photodissociation region, Astrophysics - Astrophysics of Galaxies, 01 natural sciences, Stars, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), 0103 physical sciences, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], 010306 general physics, 010303 astronomy & astrophysics, Line (formation)
Abstract

The expansion of Galactic HII regions can trigger the formation of a new generation of stars. However, little is know about the physical conditions that prevail in these regions. We study the physical conditions that prevail in specific zones towards expanding HII regions that trace representative media such as the photodissociation region, the ionized region, and condensations with and without ongoing star formation. We use the SPIRE Fourier Transform Spectrometer (FTS) on board $Herschel$ to observe the HII region RCW 120. Continuum and lines are observed in the $190-670\,\mu$m range. Line intensities and line ratios are obtained and used as physical diagnostics of the gas. We used the Meudon PDR code and the RADEX code to derive the gas density and the radiation field at nine distinct positions including the PDR surface and regions with and without star-formation activity. For the different regions we detect the atomic lines [NII] at $205\,\mu$m and [CI] at $370$ and $609\,\mu$m, the $^{12}{\rm CO}$ ladder between the $J=4$ and $J=13$ levels and the $^{13}{\rm CO}$ ladder between the $J=5$ and $J=14$ levels, as well as CH$ ^{+} $ in absorption. We find gas temperatures in the range $45-250\,$K for densities of $10^4-10^6\,{\rm cm}^{-3}$, and a high column density on the order of $N_{{\rm H}}\sim10^{22}\,{\rm cm}^{-2}$ that is in agreement with dust analysis. The ubiquitousness of the atomic and CH$ ^{+} $ emission suggests the presence of a low-density PDR throughout RCW 120. High-excitation lines of CO indicate the presence of irradiated dense structures or small dense clumps containing young stellar objects, while we also find a less dense medium ($N_{{\rm H}}\sim10^{20}\,{\rm cm}^{-2}$) with high temperatures ($80-200\,$K)., Comment: 11 pages, 11 figures, accepted by A&A

Published
2015
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48. The effects of ionization feedback on star formation: a case study of the M 16 H II region.

Author

Xu, Jin-Long, Zavagno, Annie, Yu, Naiping, Liu, Xiao-Lan, Xu, Ye, Yuan, Jinghua, Zhang, Chuan-Peng, Zhang, Si-Ju, Zhang, Guo-Yin, Ning, Chang-Chun, and Ju, Bing-Gang

Subjects
*STAR formation, *RADIO telescopes, *PROTOSTARS, *IONIZED gases, *MOLECULAR clouds, *SUPERGIANT stars
Abstract

Aims. We aim to investigate the impact of the ionized radiation from the M 16 H II region on the surrounding molecular cloud and on its hosted star formation. Methods. To present comprehensive multi-wavelength observations towards the M 16 H II region, we used new CO data and existing infrared, optical, and submillimeter data. The 12CO J = 1−0, 13CO J = 1−0, and C18O J = 1−0 data were obtained with the Purple Mountain Observatory (PMO) 13.7 m radio telescope. To trace massive clumps and extract young stellar objects (YSOs) associated with the M 16 H II region, we used the ATLASGAL and GLIMPSE I catalogs, respectively. Results. From CO data, we discern a large-scale filament with three velocity components. Because these three components overlap with each other in both velocity and space, the filament may be made of three layers. The M 16 ionized gas interacts with the large-scale filament and has reshaped its structure. In the large-scale filament, we find 51 compact cores from the ATLASGAL catalog, 20 of them being quiescent. The mean excitation temperature of these cores is 22.5 K, while this is 22.2 K for the quiescent cores. This high temperature observed for the quiescent cores suggests that the cores may be heated by M 16 and do not experience internal heating from sources in the cores. Through the relationship between the mass and radius of these cores, we obtain that 45% of all the cores are massive enough to potentially form massive stars. Compared with the thermal motion, the turbulence created by the nonthermal motion is responsible for the core formation. For the pillars observed towards M 16, the H II region may give rise to the strong turbulence. [ABSTRACT FROM AUTHOR]

Published
2019
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49. Herschel-HOBYS study of the earliest phases of high-mass star formation in NGC 6357.

Author

Russeil, D., Figueira, M., Zavagno, A., Motte, F., Schneider, N., Men'shchikov, A., Bontemps, S., André, P., Anderson, L. D., Benedettini, M., Didelon, P., Di Francesco, J., Elia, D., Könyves, V., Nguyen Luong, Q., Nony, T., Pezzuto, S., Rygl, K. L. J., Schisano, E., and Spinoglio, L.

Subjects
PROTOSTARS, STAR formation, STELLAR evolution, SPECTRAL energy distribution, EARLY stars, SUPERGIANT stars
Abstract

Aims. To constrain models of high-mass star formation it is important to identify the massive dense cores (MDCs) that are able to form high-mass star(s). This is one of the purposes of the Herschel/HOBYS key programme. Here, we carry out the census and characterise of the properties of the MDCs population of the NGC 6357 H II region. Methods. Our study is based on the Herschel/PACS and SPIRE 70−500 μm images of NGC 6357 complemented with (sub-)millimetre and mid-infrared data. We followed the procedure established by the Herschel/HOBYS consortium to extract ~0.1 pc massive dense cores using the getsources software. We estimated their physical parameters (temperatures, masses, luminosities) from spectral energy distribution (SED) fitting. Results. We obtain a complete census of 23 massive dense cores, amongst which one is found to be IR-quiet and twelve are starless, representing very early stages of the star-formation process. Focussing on the starless MDCs, we have considered their evolutionary status, and suggest that only five of them are likely to form a high-mass star. Conclusions. We find that, contrarily to the case in NGC 6334, the NGC 6357 region does not exhibit any ridge or hub features that are believed to be crucial to the massive star formation process. This study adds support for an empirical model in which massive dense cores and protostars simultaneously accrete mass from the surrounding filaments. In addition, the massive star formation in NGC 6357 seems to have stopped and the hottest stars in Pismis 24 have disrupted the filaments. [ABSTRACT FROM AUTHOR]

Published
2019
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50. Multiwavelength study of the G345.5+1.5 region.

Author

Figueira, M., López-Calderón, C., Bronfman, L., Zavagno, A., Hervías-Caimapo, C., Duronea, N., and Nyman, L.-Å.

Subjects
PROTOSTARS, STARBURSTS, STELLAR evolution, SPECTRAL energy distribution, STAR formation, STELLAR populations, SUPERGIANT stars
Abstract

Context. The star formation process requires the dust and gas present in the Milky Way to self-assemble into dense reservoirs of neutral material where the new generation of stars will emerge. Star-forming regions are usually studied in the context of Galactic surveys, but dedicated observations are sometimes needed when the study reaches beyond the survey area. Aims. A better understanding of the star formation process in the Galaxy can be obtained by studying several regions. This allows increasing the sample of objects (clumps, cores, and stars) for further statistical works and deeper follow-up studies. Here, we studied the G345.5+1.5 region, which is located slightly above the Galactic plane, to understand its star formation properties. Methods. We combined Large Apex BOlometer CAmera (LABOCA) and 12CO(4−3) transition line (NANTEN2) observations complemented with the Hi-GAL and Spitzer-GLIMPSE surveys to study the star formation toward this region. We used the Clumpfind algorithm to extract the clumps from the 870 μm and 12CO(4−3) data. Radio emission at 36 cm was used to estimate the number of H II regions and to remove the contamination from the free–free emission at 870 μm. We employed color–color diagrams and spectral energy distribution (SED) slopes to distinguish between prestellar and protostellar clumps. We studied the boundedness of the clumps through the virial parameter. Finally, we estimated the star formation efficiency (SFE) and star formation rate (SFR) of the region and used the Schmidt–Kennicutt diagram to compare its ability to form stars with other regions of the Galactic plane. Results. Of the 13 radio sources that we found using the MGPS-2 catalog, 7 are found to be associated with H II regions corresponding to late-B or early-O stars. We found 45 870 μm clumps with diameters between 0.4 and 1.2 pc and masses between 43 M⊙ and 3923 M⊙, and 107 12CO clumps with diameters between 0.4 and 1.3 pc and masses between 28 M⊙ and 9433 M⊙. More than 50% of the clumps are protostellar and bounded and are able to host (massive) star formation. High SFR and SFR density (ΣSFR) values are associated with the region, with an SFE of a few percent. Conclusions. With submillimeter, CO transition, and short-wavelength infrared observations, our study reveals a population of massive stars, protostellar and bound starless clumps, toward G345.5+1.5. This region is therefore actively forming stars, and its location in the starburst quadrant of the Schmidt–Kennicutt diagram is comparable to other star-forming regions found within the Galactic plane. [ABSTRACT FROM AUTHOR]

Published
2019
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