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47 results on '"STAR-FORMING REGIONS"'

1. Physical Properties of Galaxies at Small and Large Scales

Author

Sattari, Zahra

Subjects
Astronomy, Astrophysics, Dwarf galaxies, Galaxy environment, Galaxy evolution, Metallicity, Star-forming regions
Abstract

This thesis presents a comprehensive analysis of galaxies spanning a wide range in mass and environment, using deep optical/infrared spectroscopy and high-resolution imaging to understand the physical mechanisms deriving their formation and evolution. The research is structured around three primary studies. 1) I studied the metal enrichment of galaxies in protoclusters and the effect of the environment on the mass-metallicity relation (MZR). I found that massive galaxies residing in protoclusters are metal-deficient compared to galaxies in the field. This implies that primordial cold gas, channeled through cosmic filaments, dilutes the metal content of the protocluster; 2) I investigated the fraction of clumpy galaxies at 0.5< z< 3, using UVCANDELS and CANDELS imaging data to examine clump properties in star-forming galaxies. The results reveal a peak in clumpiness around cosmic noon, with a decline towards the present and a lack of environmental dependence, suggesting that internal processes predominantly drive clump formation; 3) I extended the analyses to dwarf galaxies at z ~ 0.15, establishing a robust mass-metallicity relation and confirming the fundamental metallicity relation at low masses, highlighting the nuanced interplay between star formation rate and gas-phase metallicity. I find that the intrinsic scatter in the MZR is larger for dwarf galaxies compared to normal galaxies, indicating more diverse star formation histories and/or stronger environmental effects in these systems. This work advances our understanding of galaxy evolution across cosmic time, offering new insights into the mechanisms influencing star formation and chemical enrichment and finding the complex interplay between internal dynamics and environmental factors in shaping galaxy evolution.

Published
2024

2. Investigating the Globally Collapsing Hub–Filament Cloud G326.611+0.811

Author

Yu-Xin He, Hong-Li Liu, Xin-Di Tang, Sheng-Li Qin, Jian-Jun Zhou, Jarken Esimbek, Si-Rong Pan, Da-Lei Li, Meng-Ke Zhao, Wei-Guang Ji, and Toktarkhan Komesh

Subjects
Infrared dark clouds, Star-forming regions, Interstellar filaments, Astrophysics, QB460-466
Abstract

We present a dynamics study toward the G326.611+0.811 (G326) hub–filament system (HFS) cloud using new APEX observations of both ^13 CO and C ^18 O ( J = 2–1). The G326 HFS cloud constitutes a central hub and at least four hub-composing filaments that are divided into a major branch of filaments (F1 and F2) and a side branch (F3–F5). The cloud holds ongoing high-mass star formation as characterized by three massive dense clumps (i.e., 370–1100 M _⊙ and 0.14–0.16 g cm ^−2 for C1–C3) with high clump-averaged mass infalling rates (>10 ^−3 M _⊙ yr ^−1 ) within the major filament branch, and the associated point sources bright at 70 μ m, typical of young protostars. Along the five filaments, velocity gradients are found in both ^13 CO and C ^18 O ( J = 2–1) emission, suggesting that filament-aligned gravitational collapse toward the central hub (i.e., C2) is responsible for the high-mass star formation therein. Moreover, a periodic velocity oscillation along the major filament branch is revealed in both ^13 CO and C ^18 O ( J = 2–1) emission with a characteristic wavelength of ∼3.5 pc and an amplitude of ∼0.31–0.38 km s ^−1 . We suggest that this pattern of velocity oscillation in G326 could arise from clump-forming gas motion induced by gravitational instabilities. The prevalent velocity gradients, fragmentation of the major branch of filaments, and the ongoing collapse of the three massive dense clumps are indicative that G326 is an HFS undergoing global collapse.

Published
2023
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3. Unusually Powerful Flare Phenomenon of the Water Maser in W51 and the Possibility of Detecting Gravitational Radiation from It

Author

A. E. Volvach, L. N. Volvach, and M. G. Larionov

Subjects
Water masers, Astrophysical masers, Star-forming regions, Astrophysics, QB460-466
Abstract

Because of detailed monitoring of the 22.2 GHz water maser, carried out from 2021 October to 2023 May, a very powerful flare phenomenon was detected in the galactic object W51 near the radial velocity of 60 km s ^−1 with the amplitude of 140 kJy. A phenomenon of this magnitude was unprecedented in the entire history of observations of the source. Eleven short flares were recorded. The exponential increase and decrease in the flare flux density while reducing in their spectral line widths indicated that water masers were in an unsaturated state during the flares. All flares were located at the top of the less powerful Flare 0 with the amplitude of 13.5 kJy and the spectral line half-width of 3.0 km s ^−1 . Such a wide line of the water maser, as well as the amplitude, of the flare phenomenon are so far unique discoveries. The water maser of Flare 0 may have been saturated and created a significant input flux density for other flares of this phenomenon. The extremely high density of maser spots in a cluster led to their partial overlap on the observer’s line of sight. This also confirmed the hypothesis about the need for a significant length of the path along which the generation of maser radiation occurs. New parameters of water masers and the most important physical conclusions have been obtained. The possibility of detecting gravitational waves from massive binary stars at the stage of evolution close to merging is considered for the case of W51 Main.

Published
2023
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4. Investigating the Impact of Metallicity on Star Formation in the Outer Galaxy. I. VLT/KMOS Survey of Young Stellar Objects in Canis Major

Author

Dominika Itrich, Agata Karska, Marta Sewiło, Lars E. Kristensen, Gregory J. Herczeg, Suzanne Ramsay, William J. Fischer, Benoît Tabone, Will R. M. Rocha, Maciej Koprowski, Ngân Lê, and Beata Deka-Szymankiewicz

Subjects
Star-forming regions, Astrophysics, QB460-466
Abstract

The effects of metallicity on the evolution of protoplanetary disks may be studied in the outer Galaxy where the metallicity is lower than in the solar neighborhood. We present the VLT/KMOS integral field spectroscopy in the near-infrared of ∼120 candidate young stellar objects (YSOs) in the CMa- ℓ 224 star-forming region located at a Galactocentric distance of 9.1 kpc. We characterize the YSO accretion luminosities and accretion rates using the hydrogen Br γ emission and find a median accretion luminosity of $\mathrm{log}({L}_{\mathrm{acc}})=-{0.82}_{-0.82}^{+0.80}{L}_{\odot }$ . Based on the measured accretion luminosities, we investigate the hypothesis of star formation history in the CMa- ℓ 224. Their median values suggest that Cluster C, where most of YSO candidates have been identified, might be the most evolved part of the region. The accretion luminosities are similar to those observed toward low-mass YSOs in the Perseus and Orion molecular clouds, and they do not reveal the impact of lower metallicity. Similar studies in other outer Galaxy clouds covering a wide range of metallicities are critical to gain a complete picture of star formation in the Galaxy.

Published
2023
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5. Characterization of dense Planck clumps observed with Herschel and SCUBA-2

Author

E. Mannfors, Leonardo Bronfman, Hsien Shang, Miikka S. Väisälä, Archana Soam, Mika Juvela, Jinhua He, Gwanjeon Kim, Alessio Traficante, Patricio Sanhueza, Chang Won Lee, Kee-Tae Kim, H. Kirppu, Harriet Parsons, David Eden, J. Montillaud, Tie Liu, Ken'ichi Tatematsu, Particle Physics and Astrophysics, and Department of Physics

Subjects
Opacity, Young stellar object, Milky Way, Extinction (astronomy), MU-M, PHYSICAL-PROPERTIES, FOS: Physical sciences, Context (language use), Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, MOLECULAR CLOUD, ISM: clouds, 01 natural sciences, PIXEL BOLOMETER CAMERA, MAGNETIC-FIELDS, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, GOULD BELT SURVEY, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, ISM: general, infrared: ISM, STAR-FORMING REGIONS, Physics, HI-GAL, stars: formation, 010308 nuclear & particles physics, Star formation, Molecular cloud, Galactic Center, Astronomy and Astrophysics, 115 Astronomy, Space science, Astrophysics - Astrophysics of Galaxies, 13. Climate action, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), GALACTIC COLD CLUMPS, dust, extinction, methods: observational, OPHIUCHI MAIN CLOUD
Abstract

We aim to characterize a diverse selection of dense, potentially star-forming cores, clumps, and clouds within the Milky Way in terms of their dust emission and SF activity. We studied 53 fields that have been observed in the JCMT SCUBA-2 continuum survey SCOPE and have been mapped with Herschel. We estimated dust properties by fitting Herschel observations with modified blackbody functions, studied the relationship between dust temperature and dust opacity spectral index $\beta$, and estimated column densities. We extracted clumps from the SCUBA-2 850 $\mu$m maps with the FellWalker algorithm and examined their masses and sizes. Clumps are associated with young stellar objects found in several catalogs. We estimated the gravitational stability of the clumps with virial analysis. The clumps are categorized as unbound starless, prestellar, or protostellar. We find 529 dense clumps, typically with high column densities from (0.3-4.8)$\times 10^{22}$ cm$^{-2}$, with a mean of (1.5$\pm$0.04)$\times10^{22}$ cm$^{-2}$, low temperatures ($T\sim $10-20 K), and estimated submillimeter $\beta$ =1.7$\pm$0.1. We detect a slight increase in opacity spectral index toward millimeter wavelengths. Masses of the sources range from 0.04 $M_\odot$ to 4259 $M_\odot$. Mass, linear size, and temperature are correlated with distance. Furthermore, the estimated gravitational stability is dependent on distance, and more distant clumps appear more virially bound. Finally, we present a catalog of properties of the clumps.Our sources present a large array of SF regions, from high-latitude, nearby diffuse clouds to large SF complexes near the Galactic center. Analysis of these regions will continue with the addition of molecular line data, which will allow us to study the densest regions of the clumps in more detail., Comment: 60 pages (article 18 pages), 73 figures To be published in A&A

Published
2021

6. Gravity Driven Magnetic Field at ~1000 au Scales in High-mass Star Formation

Author

Andrés E. Guzmán, Fernando A. Olguin, James M. Jackson, Huei-Ru Vivien Chen, Ian W. Stephens, Ken'ichi Tatematsu, Andrea Silva, Ya-Wen Tang, Paulo C. Cortes, Marco Padovani, P. Frau, Qizhou Zhang, Charles L. H. Hull, Josep M. Girart, Luis A. Zapata, Benjamin Wu, Daniele Galli, Takeshi Sakai, Xing Lu, Manuel Fernández-López, Patrick M. Koch, Fumitaka Nakamura, Patricio Sanhueza, Japan Society for the Promotion of Science, and Ministerio de Ciencia, Innovación y Universidades (España)

Subjects
Gravity (chemistry), 010504 meteorology & atmospheric sciences, Polarimetry, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, purl.org/becyt/ford/1 [https], Star forming regions, Massive stars, 0103 physical sciences, Star-forming regions, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences, Physics, Dust continuum emission, Star formation, Astronomy and Astrophysics, purl.org/becyt/ford/1.3 [https], Astrophysics - Astrophysics of Galaxies, Young stellar objects, Magnetic field, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), Magnetic fields, High mass
Abstract

A full understanding of high-mass star formation requires the study of one of the most elusive components of the energy balance in the interstellar medium: magnetic fields. We report Atacama Large Millimeter/submillimeter Array (ALMA) 1.2 mm, high-resolution (700 au) dust polarization and molecular line observations of the rotating hot molecular core embedded in the high-mass star-forming region IRAS 18089-1732. The dust continuum emission and magnetic field morphology present spiral-like features resembling a whirlpool. The velocity field traced by the H13CO+ (J = 3-2) transition line reveals a complex structure with spiral filaments that are likely infalling and rotating, dragging the field with them. We have modeled the magnetic field and find that the best model corresponds to a weakly magnetized core with a mass-to-magnetic-flux ratio (λ) of 8.38. The modeled magnetic field is dominated by a poloidal component, but with an important contribution from the toroidal component that has a magnitude of 30% of the poloidal component. Using the Davis-Chandrasekhar-Fermi method, we estimate a magnetic field strength of 3.5 mG. At the spatial scales accessible to ALMA, an analysis of the energy balance of the system indicates that gravity overwhelms turbulence, rotation, and the magnetic field. We show that high-mass star formation can occur in weakly magnetized environments, with gravity taking the dominant role., P.S. and B.W. were partially supported by a Grant-in-Aid for Scientific Research (KAKENHI number 18H01259) of the Japan Society for the Promotion of Science (JSPS). J.M.G. is supported by the Spanish grant AYA2017-84390-C2-R (AEI/FEDER, UE). C.L.H.H. acknowledges the support of the NAOJ Fellowship and JSPS KAKENHI grants 18K13586 and 20K14527. J.M.J.'s research was conducted in part at the SOFIA Science Center, which is operated by the Universities Space Research Association under contract NNA17BF53C with the National Aeronautics and Space Administration. K.T. was supported by JSPS KAKENHI grant No. 20H05645. Data analysis was in part carried out on the Multi-wavelength Data Analysis System operated by the Astronomy Data Center (ADC), National Astronomical Observatory of Japan. This paper makes use of the following ALMA data: ADS/JAO.ALMA#2017.1.00101.S. ALMA is a partnership of ESO (representing its member states), NSF (USA) and NINS (Japan), together with NRC (Canada), MOST and ASIAA (Taiwan), and KASI (Republic of Korea), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/NRAO and NAOJ.

Published
2021

7. SOFIA FEEDBACK survey: exploring the dynamics of the stellar wind driven shell of RCW 49

Author

Oliver Ricken, Christof Buchbender, C. H. M. Pabst, Robert Simon, Mark G. Wolfire, A. G. G. M. Tielens, Arshia M. Jacob, R. Higgins, Rolf Güsten, R. Karim, Nicola Schneider, C. Guevara, S. Kabanovic, M. Tiwari, Marc W. Pound, and Juergen Stutzki

Subjects
010504 meteorology & atmospheric sciences, Infrared, Astrophysics::High Energy Astrophysical Phenomena, Shell (structure), FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, law.invention, Momentum, Telescope, law, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Star-forming regions, Spectral resolution, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Stellar feedback, 1602, 1565, 0105 earth and related environmental sciences, Line (formation), Physics, Astronomy and Astrophysics, Radius, Astrophysics - Astrophysics of Galaxies, Wavelength, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), Astrophysics::Earth and Planetary Astrophysics
Abstract

We unveil the stellar wind driven shell of the luminous massive star-forming region of RCW 49 using SOFIA FEEDBACK observations of the [CII] 158 $\mu$m line. The complementary dataset of the $^{12}$CO and $^{13}$CO J = 3 - 2 transitions is observed by the APEX telescope and probes the dense gas toward RCW 49. Using the spatial and spectral resolution provided by the SOFIA and APEX telescopes, we disentangle the shell from a complex set of individual components of gas centered around RCW 49. We find that the shell of radius ~ 6 pc is expanding at a velocity of 13 km s$^{-1}$ toward the observer. Comparing our observed data with the ancillary data at X-Ray, infrared, sub-millimeter and radio wavelengths, we investigate the morphology of the region. The shell has a well defined eastern arc, while the western side is blown open and is venting plasma further into the west. Though the stellar cluster, which is ~ 2 Myr old gave rise to the shell, it only gained momentum relatively recently as we calculate the shell's expansion lifetime ~ 0.27 Myr, making the Wolf-Rayet star WR20a a likely candidate responsible for the shell's re-acceleration., Comment: 31 pages, 17 figures

Published
2021

8. Which Molecular Cloud Structures Are Bound?

Author

Marc-Antoine Miville-Deschenes, Mark H. Heyer, Neal J. Evans, Manuel Merello, Quang Nguyen-Luong, 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 Paris Cité (UPCité), and Université Paris Cité (UPCité)

Subjects
Physics, Molecular cloud, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics - Astrophysics of Galaxies, Space and Planetary Science, [SDU]Sciences of the Universe [physics], Astrophysics of Galaxies (astro-ph.GA), Molecular clouds, Star-forming regions, Astrophysics::Galaxy Astrophysics
Abstract

We analyze surveys of molecular cloud structures defined by tracers ranging from CO $J = 1-0$ through $^{13}$CO $J = 1-0$ to dust emission together with NH$_3$ data. The mean value of the virial parameter and the fraction of mass in bound structures depends on the method used to identify structures. Generally, the virial parameter decreases and the fraction of mass in bound structures increases with the effective density of the tracer, the surface density and mass of the structures, and the distance from the center of a galaxy. For the most complete surveys of structures in the Galaxy defined by CO $J = 1-0$, the fraction of mass that is in bound structures is 0.19. For catalogs of other galaxies based on CO $J = 2-1$, the fraction is 0.35. These results offer substantial alleviation of the fundamental problem of slow star formation. If only clouds found to be bound are counted and they are assumed to collapse in a free-fall time at their mean cloud density, the sum over all clouds in a complete survey of the Galaxy yields a predicted star formation rate of 46 solar masses per year, a factor of 6.5 less than if all clouds are bound., Comment: 26 pages, 14 figures, accepted to ApJ

Published
2021
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9. The JCMT BISTRO Survey: The Distribution of Magnetic Field Strengths towards the OMC-1 Region

Author

Hwang, Jihye, Kim, Jongsoo, Pattle, Kate, Kwon, Woojin, Sadavoy, Sarah, Koch, Patrick M., Hull, Charles L. H., Johnstone, Doug, Furuya, Ray S., Won Lee, Chang, Arzoumanian, Doris, Tahani, Mehrnoosh, Eswaraiah, Chakali, Liu, Tie, Kirchschlager, Florian, Kim, Kee-Tae, Tamura, Motohide, Kwon, Jungmi, Lyo, A-Ran, Soam, Archana, Kang, Ji-hyun, Bourke, Tyler L., Matsumura, Masafumi, Mairs, Steve, Kim, Gwanjeong, Park, Geumsook, Nakamura, Fumitaka, Onaka, Takashi, Tang, Xindi, Liu, Hong-Li, Ward-Thompson, Derek, Li, Di, Hoang, Thiem, Hasegawa, Tetsuo, Qiu, Keping, Lai, Shih-Ping, Bastien, Pierre, 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
Distribution (number theory), Polarimetry, FOS: Physical sciences, Astrophysics, 01 natural sciences, interstellar magnetic fields, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Star-forming regions, 010306 general physics, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, polarimetry, Physics, dense interstellar clouds, Astronomy and Astrophysics, Astrophysics - Astrophysics of Galaxies, Magnetic field, [SDU]Sciences of the Universe [physics], Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), star forming regions
Abstract

Measurement of magnetic field strengths in a molecular cloud is essential for determining the criticality of magnetic support against gravitational collapse. In this paper, as part of the JCMT BISTRO survey, we suggest a new application of the Davis-Chandrasekhar-Fermi (DCF) method to estimate the distribution of magnetic field strengths in the OMC-1 region. We use observations of dust polarization emission at 450 $\mu$m and 850 $\mu$m, and C$^{18}$O (3-2) spectral line data obtained with the JCMT. We estimate the volume density, the velocity dispersion and the polarization angle dispersion in a box, 40$''$ $\times$ 40$''$ (5$\times$5 pixels), which moves over the OMC-1 region. By substituting three quantities in each box to the DCF method, we get magnetic field strengths over the OMC-1 region. We note that there are very large uncertainties in inferred field strengths, as discussed in detail in this paper. The field strengths vary from 0.8 to 26.4 mG and their mean value is about 6 mG. Additionally, we obtain maps of the mass-to-flux ratio in units of a critical value and the Alfv$\acute{e}$n mach number. The central parts of the BN-KL and South (S) clumps in the OMC-1 region are magnetically supercritical, so the magnetic field cannot support the clumps against gravitational collapse. However, the outer parts of the region are magnetically subcritical. The mean Alfv$\acute{e}$n mach number is about 0.4 over the region, which implies that the magnetic pressure exceeds the turbulent pressure in the OMC 1 region., Comment: 28 pages

Published
2021
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10. Pre-Supernova Stellar Feedback: from the Milky Way to Reionization

Author

Olivier, Grace Margaret

Subjects
Astrophysics, Astronomy, Galaxy formation, Stellar feedback, Star formation, Star-forming regions, H II regions, Compact H II region, Dwarf galaxies, Ultraviolet astronomy, Galaxy chemical evolution, Galaxy spectroscopy, High-redshift galaxies, Emission line galaxies
Abstract

Galaxy formation and evolution are driven by stars and star formation. Star formation is fundamental for shaping the universe as we see it today as part of the cosmic ecosystems encompassing galaxies, yet half of the physics that determines how much gas forms into stars – the stellar feedback (injection of energy and momentum to the surrounding material) half of the tug-of-war between gravity and stellar feedback – have only recently become a focus for observational astronomers. Theoretical explorations of stellar feedback have been extensive for the past four decades and our current understanding of star-forming galaxies comes primarily through extensive modeling and simulations with sub-grid physics prescriptions based on a handful of observations. In order to secure the basis for these sub-grid physics models and expand our understanding of star-formation and the effects of massive stars during all epochs of the universe, more observations of these processes are needed. Observations of star forming regions provide the foundation to anchor simulations and observations of analogues to high-redshift galaxies help determine the sources that reionized the universe and the role stars played in during the Epoch of Reionization. With multiwavelength observations of H ii regions in the Milky Way, I have probed the effects of stellar feedback in dynamics of H ii regions, providing the necessary basis for defining the sub-grid physics in simulations. With multiwavelength observations of nearby galaxies with properties similar to galaxies in the EoR (low mass: < 107 M⊙; low metallicity: < 0.15 Z⊙; and high star-formation rates: > 10−1.2 M⊙/yr), I have determined the properties of sources that produce the photoionization feedback we observe and which sources ionized the universe in the Reionization Era. With X-ray observations of a massive colliding wind binary I have explored the effects of stellar wind feedback on small spatial scales and found that wind prescriptions assume symmetric mass-loss, however observations indicate mass-loss is asymmetric from massive stars. Overall, these results show the variety of ways astronomers can observe stellar feedback and incorporate these physics into our understanding of galaxy formation and evolution.

Published
2022

11. Dust evolution in the dwarf galaxy Holmberg II.

Author

Wiebe, D., Khramtsova, M., Egorov, O., and Lozinskaya, T.

Subjects
*DWARF galaxies, *STAR formation, *PHOTOMETRY, *TELESCOPES, *ASTROPHYSICS, *POLYCYCLIC aromatic hydrocarbons, *ASTRONOMICAL research
Abstract

A detailed photometric study of star-forming regions (SFRs) in the galaxy Holmberg II has been carried out using the archival observational data from the far infrared to the ultraviolet obtained with the GALEX, Spitzer, and Herschel telescopes. Spectroscopic observations with the 6-m BTA telescope (Special Astrophysical Observatory of the Russian Academy of Sciences) are used to estimate the ages and metallicities of SFRs. The ages of SFRs have been correlated for the first time with their emission parameters in a wide spectral range and with the physical parameters determined by fitting the observed spectra. It is shown that the fluxes at 8 and 24 µm characterizing the emission from polycyclic aromatic hydrocarbons (PAHs) and hot dust grains decrease with age, but their ratio increases. This implies that the relative contribution from PAHs to the total infrared flux increases with age. It is hypothesized that the detected increase in the ratio of the fluxes at 8 and 24 µm is related to the increase in the relative PAH fraction due to the destruction of larger grains. [ABSTRACT FROM AUTHOR]

Published
2014
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12. High-Energy Particles and Radiation in Star-Forming Regions

Author

Andrei M. Bykov, Alexandre Marcowith, Eli Waxman, Maria E Kalyashova, Elena Amato, J. M. Diederik Kruijssen, Laboratoire Univers et Particules de Montpellier (LUPM), Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Montpellier 2 - Sciences et Techniques (UM2), and FRA

Subjects
010504 meteorology & atmospheric sciences, Stellar population, neutrino: energy: high, feedback, Starburst galaxies, Astrophysics, 01 natural sciences, particle: acceleration, propagation, site, Astrophysics::Solar and Stellar Astrophysics, Star-forming regions, 010303 astronomy & astrophysics, magnetic field: fluctuation, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, star: formation, Particle acceleration, Supernova, cosmic radiation, cluster: massive, Neutrino, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics::High Energy Astrophysical Phenomena, kinetic, FOS: Physical sciences, Cosmic ray, Astrophysics::Cosmology and Extragalactic Astrophysics, OB associations, 0103 physical sciences, supernova, structure, Cosmic rays, Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences, energy: magnetic, Young massive star clusters, Star formation, Astronomy and Astrophysics, stability, Astrophysics - Astrophysics of Galaxies, Galaxy, star: massive, Stars, 13. Climate action, Space and Planetary Science, gamma ray, Astrophysics of Galaxies (astro-ph.GA), nonlinear, galaxy, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

Non-thermal particles and high-energy radiation can play a role in the dynamical processes in star-forming regions and provide an important piece of the multiwavelength observational picture of their structure and components. Powerful stellar winds and supernovae in compact clusters of massive stars and OB associations are known to be favourable sites of high-energy particle acceleration and sources of non-thermal radiation and neutrinos. Namely, young massive stellar clusters are likely sources of the PeV (petaelectronvolt) regime cosmic rays (CRs). They can also be responsible for the cosmic ray composition, e.g., 22Ne/20Ne anomalous isotopic ratio in CRs. Efficient particle acceleration can be accompanied by super-adiabatic amplification of the fluctuating magnetic fields in the systems converting a part of kinetic power of the winds and supernovae into the magnetic energy through the CR-driven instabilities. The escape and CR propagation in the vicinity of the sources are affected by the non-linear CR feedback. These effects are expected to be important in starburst galaxies, which produce high-energy neutrinos and gamma-rays. We give a brief review of the theoretical models and observational data on high-energy particle acceleration and their radiation in star-forming regions with young stellar population., 41 pages, Space Science Reviews v.216, id 42, topical collection Star Formation

Published
2020
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13. RadioAstron probes the ultra-fine spatial structure in the H2O maser emission in the star forming region W49N

Author

V.Y. Avdeev, A. Alakoz, A. M. Sobolev, N.N. Shakhvorostova, Hiroshi Imai, and James M. Moran

Subjects
Atmospheric Science, 010504 meteorology & atmospheric sciences, Astrophysics::High Energy Astrophysical Phenomena, SPACE VLBI, STAR-FORMING REGION, MASERS, Aerospace Engineering, Flux, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Star (graph theory), 01 natural sciences, Spectral line, law.invention, FLUX DENSITIES, law, 0103 physical sciences, Maser, 010303 astronomy & astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), Astrophysics::Galaxy Astrophysics, INTERSTELLAR MEDIUMS, 0105 earth and related environmental sciences, Physics, STAR-FORMING REGIONS, Range (particle radiation), Star formation, Turbulence, EARTH (PLANET), Astronomy and Astrophysics, Astrophysics - Astrophysics of Galaxies, H2O MASERS, GALACTIC H2O MASERS, Interstellar medium, Geophysics, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), General Earth and Planetary Sciences, SPATIAL STRUCTURE, MASER EMISSIONS, Astrophysics - Instrumentation and Methods for Astrophysics, STARS, MASSIVE STARS
Abstract

H$_2$O maser emission associated with the massive star formation region W49N were observed with the Space-VLBI mission RadioAstron. The procedure for processing of the maser spectral line data obtained in the RadioAstron observations is described. Ultra-fine spatial structures in the maser emission were detected on space-ground baselines of up to 9.6 Earth diameters. The correlated flux densities of these features range from 0.1% to 0.6% of the total flux density. These low values of correlated flux density are probably due to turbulence either in the maser itself or in the interstellar medium., Comment: Accepted for publication in Advances in Space Research

Published
2020

14. The Star Formation in Radio Survey: 3 - 33 GHz Imaging of Nearby Galaxy Nuclei and Extranuclear Star-forming Regions

Author

Jean L. Turner, R. C. Kennicutt, S. T. Linden, Emmanuel Momjian, D. Dong, Eric J. Murphy, Eva Schinnerer, and David S. Meier

Subjects
FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astronomy & Astrophysics, Atomic, 01 natural sciences, Spectral line, Radio spectrum, Particle and Plasma Physics, Extragalactic radio sources, Galaxy evolution, H II regions, 0103 physical sciences, Galaxy formation and evolution, Star-forming regions, Nuclear, Radio astronomy, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Physics, Spectral index, Spiral galaxies, Spiral galaxy, 010308 nuclear & particles physics, Star formation, Molecular, Astronomy and Astrophysics, Galaxies, Astrophysics - Astrophysics of Galaxies, Galaxy, Radio continuum emission, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), Radio interferometry, Astronomical and Space Sciences, Physical Chemistry (incl. Structural)
Abstract

We present 3, 15, and 33 GHz imaging towards galaxy nuclei and extranuclear star-forming regions using the Karl G. Jansky Very Large Array as part of the Star Formation in Radio Survey. With $3-33$ GHz radio spectra, we measured the spectral indices and corresponding thermal (free-free) emission fractions for a sample of 335 discrete regions having significant detections in at least two radio bands. After removing 14 likely background galaxies, we find that the median thermal fraction at 33 GHz is $92 \pm 0.8\%$ with a median absolute deviation of $11\%$, when a two-component power-law model is adopted to fit the radio spectrum. Limiting the sample to 238 sources that are confidently identified as star-forming regions, and not affected by potential AGN contamination (i.e., having galactocentric radii $r_{\rm G} \geq 250$ pc), results in a median thermal fraction of $93 \pm 0.8 \%$ with a median absolute deviation of $10\%$. We further measure the thermal fraction at 33 GHz for 163 regions identified at 7" resolution to be $94 \pm 0.8 \%$ with a median absolute deviation of $8\%$. Together, these results confirm that free-free emission dominates the radio spectra of star-forming regions on scales up to $\sim$500 pc in normal star-forming galaxies. We additionally find a factor of $\sim$1.6 increase in the scatter of the measured spectral index and thermal fraction distributions as a function of decreasing galactocentric radius. This trend is likely reflective of the continuous star-formation activity occurring in the galaxy centers, resulting a larger contribution of diffuse nonthermal emission relative to star-forming regions in the disk., Comment: 57 pages, 23 figures, 7 tables, accepted for publication in ApJS

Published
2020
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15. Local Starburst Conditions and Formation of GRB 980425/SN 1998bw within a Collisional Ring

Author

S. C. Madden, Andrew J. Levan, V. Arumugam, E. Le Floc'h, Frederic Bournaud, S. Roychowdhury, D. Cormier, Martin Zwaan, Florent Renaud, Lise Christensen, Elena Pian, M. Arabsalmani, Institut de RadioAstronomie Millimétrique (IRAM), 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, 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), Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112)), and 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)

Subjects
Galaxy collisions, 010504 meteorology & atmospheric sciences, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Starburst galaxies, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Interstellar medium, Massive stars, Young massive clusters, 0103 physical sciences, Molecular clouds, Astrophysics::Solar and Stellar Astrophysics, Star-forming regions, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), GRB 980425, Star formation, Molecular cloud, Astronomy and Astrophysics, Astrophysics - Astrophysics of Galaxies, Galaxy, Supernova, Star cluster, Galaxy dynamics, Supernovae, Astrophysics - Solar and Stellar Astrophysics, 13. Climate action, Space and Planetary Science, Interacting galaxies, Astrophysics of Galaxies (astro-ph.GA), Gamma-ray bursts, Gamma-ray burst, Astrophysics - High Energy Astrophysical Phenomena, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

We present the first spatially resolved study of molecular gas in the vicinity of a Gamma Ray Burst, using CO(2-1) emission line observations with the Atacama Large Millimetre Array (ALMA) at ~50 pc scales. The host galaxy of GRB 980425 contains a ring of high column density HI gas which is likely to have formed due to a collision between the GRB host and its companion galaxy, within which the GRB is located. We detect eleven molecular gas clumps in the galaxy, seven of which are within the gas ring. The clump closest to the GRB position is at a projected separation of ~280 pc. Although it is plausible that the GRB progenitor was ejected from clusters formed in this clump, we argue that the in situ formation of the GRB progenitor is the most likely scenario. We measure the molecular gas masses of the clumps and find them to be sufficient for forming massive star clusters. The molecular gas depletion times of the clumps show a variation of ~2 dex, comparable with the large variation in depletion times found in starburst galaxies in the nearby Universe. This demonstrates the presence of starburst modes of star formation on local scales in the galaxy, even while the galaxy as a whole cannot be categorised as a starburst based on its global properties. Our findings suggest that the progenitor of GRB 9802425 was originated in a young massive star cluster formed in the starburst mode of star formation., Comment: ApJ (in press), 12 pages, 4 figures, 1 table

Published
2020
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16. Signatures of UV radiation in low-mass protostars

Author

M. Zoltowski, M. Figueira, A. Mirocha, D. Harsono, M. Gronowski, L. Tychoniec, M. Gladkowski, Agata Karska, Lars E. Kristensen, Uniwersytet Jagielloński w Krakowie = Jagiellonian University (UJ), Nicolaus Copernicus University [Toruń], Polska Akademia Nauk = Polish Academy of Sciences (PAN), Warsaw University of Technology [Warsaw], University of Copenhagen = Københavns Universitet (KU), Universiteit Leiden [Leiden], European Southern Observatory (ESO), Academia Sinica Institute of Astronomy and Astrophysics (ASIAA), Academia Sinica, National Centre for Nuclear Research [Otwock], Narodowe Centrum Badań Jądrowych (NCBJ), Laboratoire Ondes et Milieux Complexes (LOMC), Centre National de la Recherche Scientifique (CNRS)-Université Le Havre Normandie (ULH), Normandie Université (NU)-Normandie Université (NU), Institut de Physique de Rennes (IPR), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS), Polish National Science Center [UMO2018/30/M/ST9/00757, 2016/21/D/ST9/01098], First TEAM grant of the Foundation for Polish Science [POIR.04.04.00-00-5D21/18-00], VILLUM FONDENVillum Foundation [19127], EACOA Fellowship from the East Asian Core Observatories Association, European Research Council European Research Council (ERC) European Commission [811363], Institut Universitaire de France, Programme National 'Physique et Chimie du Milieu Interstellaire' (PCMI) of CNRS/INSU, CNES Centre National D'etudes Spatiales, Polish National Agency for Academic ExchangePolish National Agency for Academic Exchange (NAWA) [PPI/APM/2018/1/00036/U/001], CEA French Atomic Energy Commission, INC/INP, University of Copenhagen = Københavns Universitet (UCPH), Universiteit Leiden, Université Le Havre Normandie (ULH), Normandie Université (NU)-Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS), and Université de Rennes (UR)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Serpens, Stars: formation, Astrophysics - astrophysics of galaxies, FOS: Physical sciences, Astrophysics, individual objects: Serpens Main [ISM], Radiation, 01 natural sciences, J CO OBSERVATIONS, Stars: protostars, ISM: individual objects: Serpens Main, GAS EMISSION, KEY PROGRAM, 0103 physical sciences, Protostar, DENSE GAS, 010303 astronomy & astrophysics, protostars [stars], molecules [ISM], Astrochemistry, STAR-FORMING REGIONS, [PHYS]Physics [physics], Physics, formation [stars], jets and outflows [ISM], astrochemistry, 010308 nuclear & particles physics, MOLECULAR LINE, Astronomy and Astrophysics, YOUNG STELLAR OBJECTS, GOULD BELT, ISM: molecules, ISM: jets and outflows, 13. Climate action, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), SUBMILLIMETER-CONTINUUM, Low Mass, HERSCHEL-PACS
Abstract

Context: Ultraviolet radiation (UV) influences the physics and chemistry of star-forming regions, but its properties and significance in the immediate surroundings of low-mass protostars are still poorly understood. Aims: We aim to extend the use of the CN/HCN ratio, already established for high-mass protostars, to the low-mass regime to trace and characterize the UV field around low-mass protostars on $\sim 0.6\times0.6$ pc scales. Methods: We present $5'\times5'$ maps of the Serpens Main Cloud encompassing 10 protostars observed with the EMIR receiver at the IRAM 30 m telescope in CN 1-0, HCN 1-0, CS 3-2, and some of their isotopologues. The radiative-transfer code RADEX and the chemical model Nahoon are used to determine column densities of molecules, gas temperature and density, and the UV field strength, $G_\mathrm{0}$. Results: The spatial distribution of HCN and CS are well-correlated with CO 6-5 emission that traces outflows. The CN emission is extended from the central protostars to their immediate surroundings also tracing outflows, likely as a product of HCN photodissociation. The ratio of CN to HCN total column densities ranges from $\sim$1 to 12 corresponding to G$_0$ $\approx$ $10^{1}-10^{3}$ for gas densities and temperatures typical for outflows of low-mass protostars. Conclusions: UV radiation associated with protostars and their outflows is indirectly identified in a significant part of the Serpens Main low-mass star-forming region. Its strength is consistent with the values obtained from the OH and H$_2$O ratios observed with Herschel and compared with models of UV-illuminated shocks. From a chemical viewpoint, the CN to HCN ratio is an excellent tracer of UV fields around low- and intermediate-mass star-forming regions., Comment: 32 pages, 25 figures, accepted by A\&A

Published
2021
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17. A multi-scale exploration of a massive young stellar object - a transition disk around G305.20+0.21?

Author

W. J. de Wit, A. J. Frost, Rene D. Oudmaijer, and Stuart Lumsden

Subjects
010504 meteorology & atmospheric sciences, Young stellar object, Extinction (astronomy), FOS: Physical sciences, DUST, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astronomy & Astrophysics, individual: G305.20+0.21 [stars], Computer Science::Digital Libraries, 01 natural sciences, PARAMETERS, early-type [stars], Luminosity, Atmospheric radiative transfer codes, 0103 physical sciences, ABSORPTION, Protostar, Astrophysics::Solar and Stellar Astrophysics, MIDI, COLLAPSE, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), 0105 earth and related environmental sciences, STAR-FORMING REGIONS, Physics, Science & Technology, formation [stars], stars [infrared], GEOMETRY, Star formation, Astrophysics::Instrumentation and Methods for Astrophysics, PROTOSTARS, Astronomy and Astrophysics, Astrophysics - Astrophysics of Galaxies, imaging [stars], Physics::History of Physics, EVOLUTION, interferometric [techniques], Stars, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), Physical Sciences, Spectral energy distribution, Astrophysics::Earth and Planetary Astrophysics, EMISSION
Abstract

The rarity of young massive stars combined with the fact that they are often deeply embedded has limited the understanding of their formation. Ground based mid-infrared (IR) interferometry is one way of securing the spatial resolution required to study massive young stellar objects (MYSOs) and as the spatial-frequency coverage of such observations is often incomplete, direct-imaging can be supplementary to such a dataset. By consolidating these observations with modelling, the features of a massive protostellar environment can be constrained. This work simultaneously fits the aforementioned observations and a spectral energy distribution (SED) with a 2.5D radiative transfer model, providing an extensive view of the physical characteristics of the accreting regions of the MYSO G305.20+0.21. The high-resolution observations were obtained using the Very Large Telescope's MIDI and VISIR instruments, producing visibilities in the N-band and near-diffraction-limited imaging in the Q-band respectively. A model including a central protostar with a luminosity of $\sim$5$\times$10$^{4}$L$_{\odot}$ surrounded by a low-density bipolar cavity, a flared 1M$_{\odot}$ disk and an envelope provides a sufficient fit all three types of observation. The need to include a disk in the model implies that this MYSO follows a scaled-up version of the low-mass star formation process. The weak silicate absorption feature within the SED requires low-density envelope cavities to be successfully fit and is an atypical characteristic in comparison to previously studied MYSOs. Additionally, the inner radius of the disk must be three times the dust sublimation radius to satisfy the MIDI visibilities. The low density, low extinction environment implies the object is a more evolved MYSO and this combined with large inner radius of the disk suggests that it could be an example of a transitional disk around an MYSO., Comment: 16 pages, 8 figures

Published
2019
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18. Complex cyanides as chemical clocks in hot cores

Author

F. F. S. van der Tak, V. Allen, Catherine Walsh, and Astronomy

Subjects
Astrochemistry, 010504 meteorology & atmospheric sciences, PHASE, Continuum (design consultancy), Evaporation, Analytical chemistry, FOS: Physical sciences, Context (language use), DUST, Astrophysics, 01 natural sciences, Abundance (ecology), Phase (matter), Ionization, 0103 physical sciences, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), 0105 earth and related environmental sciences, Physics, STAR-FORMING REGIONS, ISM: individual objects: G35.20-0.74N, astrochemistry, Astronomy and Astrophysics, Astrophysics - Astrophysics of Galaxies, ISM: molecules, 3. Good health, stars: massive, EVAPORATION, MODEL, Orders of magnitude (time), Astrophysics - Solar and Stellar Astrophysics, 13. Climate action, Space and Planetary Science, GAS, Astrophysics of Galaxies (astro-ph.GA), MOLECULAR CLOUDS, MAIN, MASSIVE STARS
Abstract

In the high-mass star-forming region G35.20-0.74N, small scale (about 800 AU) chemical segregation has been observed in which complex organic molecules containing the CN group are located in a small location. We aim to determine the physical origin of the large abundance difference (about 4 orders of magnitude) in complex cyanides within G35.20-0.74 B, and we explore variations in age, gas and dust temperature, and gas density. We performed gas-grain astrochemical modeling experiments with exponentially increasing (coupled) gas and dust temperature rising from 10 to 500 K at constant H$_2$ densities of 10$^7$, 10$^8$, and 10$^9$ cm$^{-3}$. We tested the effect of varying the initial ice composition, cosmic-ray ionization rate, warm-up time (over 50, 200, and 1000 kyr), and initial (10, 15, and 25 K) and final temperatures (300 and 500 K). Varying the initial ice compositions within the observed and expected ranges does not noticeably affect the modeled abundances indicating that the chemical make-up of hot cores is determined in the warm-up stage. Complex cyanides vinyl and ethyl cyanide (CH$_2$CHCN and C$_2$H$_5$CN, respectively) cannot be produced in abundances (versus H$_2$) greater than 5x10$^{-10}$ for CH$_2$CHCN and 2x10$^{-10}$ for C$_2$H$_5$CN with a fast warm-up time (52 kyr), while the lower limit for the observed abundance of C$_2$H$_5$CN toward source B3 is 3.4x10$^{-10}$. Complex cyanide abundances are reduced at higher initial temperatures and increased at higher cosmic-ray ionization rates. Reproducing the observed abundances toward G35.20-0.74 Core B3 requires a fast warm-up at a high cosmic-ray ionization rate (1x10$^{-16}$ s$^{-1}$) at a high gas density (>10$^9$ cm$^{-3}$). G35.20-0.74 source B3 only needs to be about 2000 years older than B1/B2 for the observed chemical difference to be present. (This abstract has been shortened), 14 pages (plus 11 pages appendices), 12 figures main text

Published
2018
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19. The chemical structure of the Class 0 protostellar envelope NGC 1333 IRAS 4A

Author

E. Koumpia, Emmanuel Caux, D. A. Semenov, Adwin Boogert, F. F. S. van der Tak, Astronomy, Kapteyn Astronomical Institute, 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), and 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)

Subjects
ROTATIONAL-EXCITATION, RAY IONIZATION RATE, Astrochemistry, 010504 meteorology & atmospheric sciences, Stellar mass, FOS: Physical sciences, Context (language use), Astrophysics, 01 natural sciences, Spectral line, ISM: abundances, DEUTERATED AMMONIA, stars: low-mass, 0103 physical sciences, Radiative transfer, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), 0105 earth and related environmental sciences, Envelope (waves), Line (formation), Physics, STAR-FORMING REGIONS, stars: formation, DENSE INTERSTELLAR CLOUDS, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], LOW-MASS PROTOSTARS, astrochemistry, NGC-1333 IRAS-4, Astronomy and Astrophysics, Astrophysics - Astrophysics of Galaxies, ISM: molecules, COLLISIONAL EXCITATION, DEUTERIUM FRACTIONATION, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, [SDU]Sciences of the Universe [physics], Astrophysics of Galaxies (astro-ph.GA), MOLECULAR-HYDROGEN, Low Mass
Abstract

It is not well known what drives the chemistry of a protostellar envelope, in particular the role of the stellar mass and the outflows on its chemical enrichment. We study the chemical structure of NGC 1333 IRAS 4A in order to (i) investigate the influence of the outflows on the chemistry, (ii) constrain the age of our object, (iii) compare it with a typical high-mass protostellar envelope. In our analysis we use JCMT line mapping and HIFI pointed spectra. To study the influence of the outflow on the degree of deuteration, we compare JCMT maps of HCO+ and DCO+ with non-LTE (RADEX) models in a region that spatially covers the outflow activity of IRAS 4A. To study the envelope chemistry, we derive empirical molecular abundance profiles for the observed species using the radiative transfer code (RATRAN) and adopting a 1D dust density/temperature profile from the literature. We compare our best-fit observed abundance profiles with the predictions from the time dependent gas grain chemical code (ALCHEMIC). The CO, HCN, HNC and CN abundance require an enhanced UV field which points towards an outflow cavity. The abundances (wrt H2) are 1 to 2 orders of magnitude lower than those observed in the high mass protostellar envelope (AFGL 2591), while they are found to be similar within factors of a few with respect to CO. Differences in UV radiation may be responsible for such chemical differentiation, but temperature differences seem a more plausible explanation. The CH3OH modeled abundance profile points towards an age of > 4x10^4 yrs for IRAS 4A. The spatial distribution of H2D+ differs from that of other deuterated species, indicating an origin from a foreground colder layer (, 26 pages, 23 Figures, 6 tables, accepted for publication in A&A

Published
2017
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20. NH3 (1-0-0-0) in the pre-stellar core L1544

Author

F. F. S. van der Tak, Brunella Nisini, C. Codella, E. F. van Dishoeck, Laurent Pagani, C. M. Walmsley, Paola Caselli, Lars E. Kristensen, Yuri Aikawa, A. Faure, Luca Bizzocchi, Olli Sipilä, E. Keto, Mario Tafalla, 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), Astronomy, Max-Planck-Institut für Extraterrestriche Physik (MPE), Harvard-Smithsonian Center for Astrophysics, Observatorio Astronomico Nacional, Madrid, École normale supérieure - Paris (ENS-PSL), Dynamique des milieux interstellaires et plasmas stellaires, Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique et Atmosphères = Laboratory for Studies of Radiation and Matter in Astrophysics and Atmospheres (LERMA), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-CY Cergy Paris Université (CY)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-CY Cergy Paris Université (CY), Centre for Star and Planet Formation, SRON Netherlands Institute for Space Research, INAF-Osservatorio Astrofisico di Arcetri (INAF-OAA), INAF-Osservatorio Astronomico di Roma (INAF-OAR), Center for Computational Sciences, University of Tsukuba, Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), 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]), and Leiden Observatory

Subjects
Astrophysics, 1ST DETECTION, CLOUD CORE, 01 natural sciences, ISM: clouds, RADIATIVE-TRANSFER, Planet, Radiative transfer, Astrophysics::Solar and Stellar Astrophysics, 010303 astronomy & astrophysics, Hyperfine structure, ComputingMilieux_MISCELLANEOUS, Astrochemistry, Physics, STAR-FORMING REGIONS, [PHYS]Physics [physics], INTERSTELLAR AMMONIA, astrochemistry, ISM: molecules, DARK CLOUDS, profiles [Line], Astrophysics - Solar and Stellar Astrophysics, radiative transfer, Astrophysics::Earth and Planetary Astrophysics, THERMOMETER, methods: observational, clouds [ISM], FOS: Physical sciences, Rotational transition, 0103 physical sciences, Molecule, observational [Methods], Spectral resolution, molecules [ISM], Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics, 010308 nuclear & particles physics, Astronomy and Astrophysics, line: profiles, Astrophysics - Astrophysics of Galaxies, ODIN SATELLITE, Pre-stellar core, 13. Climate action, Space and Planetary Science, WATER-VAPOR, Astrophysics of Galaxies (astro-ph.GA), EMISSION, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Order of magnitude
Abstract

Pre-stellar cores represent the initial conditions in the process of star and planet formation, therefore it is important to study their physical and chemical structure. Because of their volatility, nitrogen-bearing molecules are key to study the dense and cold gas present in pre-stellar cores. The NH_3 rotational transition detected with Herschel-HIFI provides a unique combination of sensitivity and spectral resolution to further investigate physical and chemical processes in pre-stellar cores. Here we present the velocity-resolved Herschel-HIFI observations of the ortho-NH_3(1_0-0_0) line at 572 GHz and study the abundance profile of ammonia across the pre-stellar core L1544 to test current theories of its physical and chemical structure. Recently calculated collisional coefficients have been included in our non-LTE radiative transfer code to reproduce Herschel observations. A gas-grain chemical model, including spin-state chemistry and applied to the (static) physical structure of L1544 is also used to infer the abundance profile of ortho-NH_3 . The hyperfine structure of ortho-NH_3(1_0-0_0) is resolved for the first time in space. All the hyperfine components are strongly self-absorbed. The profile can be reproduced if the core is contracting in quasi-equilibrium, consistent with previous work, and if the NH_3 abundance is slightly rising toward the core centre, as deduced from previous interferometric observations of para-NH_3(1,1). The chemical model overestimates the NH_3 abundance at radii between ~ 4000 and 15000 AU by about two orders of magnitude and underestimates the abundance toward the core centre by more than one order of magnitude. Our observations show that chemical models applied to static clouds have problems in reproducing NH_3 observations., Comment: accepted for publication in A&A Letters

Published
2017
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21. Chasing discs around O-type (proto)stars: Evidence from ALMA observations

Author

M. T. Beltrán, Victor M. Rivilla, C. M. Walmsley, Peter Schilke, Luca Moscadelli, Timea Csengeri, V. Allen, M. S. N. Kumar, Joseph C. Mottram, Th. Henning, A. Ahmadi, Rolf Kuiper, Melvin Hoare, Roberto Galván-Madrid, Ciriaco Goddi, Daniele Galli, Hans Zinnecker, Sandra Etoka, Stuart Lumsden, Luke T. Maud, Henrik Beuther, Gary A. Fuller, Sarita Vig, Álvaro Sánchez-Monge, Pamela Klaassen, Riccardo Cesaroni, Leonardo Testi, Thomas Peters, F. F. S. van der Tak, Katharine G. Johnston, and Astronomy

Subjects
H II REGIONS, Astronomy, HOT MOLECULAR CORE, Astrophysics, Permission, 01 natural sciences, early-type [Stars], 0103 physical sciences, RMS SURVEY, 010303 astronomy & astrophysics, molecules [ISM], formation [Stars], CANDIDATE MASSIVE YSOS, STAR-FORMING REGIONS, Physics, stars: formation, 010308 nuclear & particles physics, European research, Astronomy and Astrophysics, HYPERCOMPACT HII-REGIONS, Physik (inkl. Astronomie), stars: early-type, GALACTIC PLANE SURVEY, YOUNG STELLAR OBJECTS, ISM: molecules, Stars, Action (philosophy), Space and Planetary Science, DISTANCE-LIMITED SAMPLE, MSX SOURCE SURVEY
Abstract

Context. Circumstellar discs around massive stars could mediate the accretion onto the star from the infalling envelope, and could minimize the effects of radiation pressure. Despite such a crucial role, only a few convincing candidates have been provided for discs around deeply embedded O-type (proto)stars. Aims: In order to establish whether disc-mediated accretion is the formation mechanism for the most massive stars, we have searched for circumstellar, rotating discs around a limited sample of six luminous (>105L☉) young stellar objects. These objects were selected on the basis of their IR and radio properties in order to maximize the likelihood of association with disc+jet systems. Methods: We used ALMA with 0.̋2 resolution to observe a large number of molecular lines typical of hot molecular cores. In this paper we limit our analysis to two disc tracers (methyl cyanide, CH3CN, and its isotopologue, 13CH3CN), and an outflow tracer (silicon monoxide, SiO). Results: We reveal many cores, although their number depends dramatically on the target. We focus on the cores that present prominent molecular line emission. In six of these a velocity gradient is seen across the core,three of which show evidence of Keplerian-like rotation. The SiO data reveal clear but poorly collimated bipolar outflow signatures towards two objects only. This can be explained if real jets are rare (perhaps short-lived) in very massive objects and/or if stellar multiplicity significantly affects the outflow structure.For all cores with velocity gradients, the velocity field is analysed through position-velocity plots to establish whether the gas is undergoing rotation with νrot ∝ R- α, as expected for Keplerian-like discs. Conclusions: Our results suggest that in three objects we are observing rotation in circumstellar discs, with three more tentative cases, and one core where no evidence for rotation is found. In all cases but one, we find that the gas mass is less than the mass of any embedded O-type star, consistent with the (putative) discs undergoing Keplerian-like rotation. With the caveat of low number statistics, we conclude that the disc detection rate could be sensitive to the evolutionary stage of the young stellar object. In young, deeply embedded sources, the evidence for discs could be weak because of confusion with the surrounding envelope, while in the most evolved sources the molecular component of the disc could have already been dispersed. Only in those objects that are at an intermediate stage of the evolution would the molecular disc be sufficiently prominent and relatively less embedded to be detectable by mm/submm observations.

Published
2017
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22. Analysis of the Herschel/HEXOS Spectral Survey Towards Orion South: A massive protostellar envelope with strong external irradiation

Author

J. R. Goicoechea, Laurent Pagani, J. C. Pearson, Emmanuel Caux, Volker Ossenkopf-Okada, D. Johnstone, Rene Plume, S. Cabrit, P. F. Goldsmith, E. A. Bergin, F. F. S. van der Tak, D. C. Lis, K. Tahani, Holger S. P. Müller, V. Tolls, Thomas G. Phillips, Karl M. Menten, and Astronomy

Subjects
010504 meteorology & atmospheric sciences, Thermodynamic equilibrium, MU-M, FOS: Physical sciences, ISM: individual objects (Orion South), Astrophysics, 01 natural sciences, Article, ISM: abundances, Spectral line, individual objects (Orion South) [ISM], SUBMILLIMETER ARRAY, 0103 physical sciences, OBSERVATIONAL DATA, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), molecules [ISM], 0105 earth and related environmental sciences, Envelope (waves), abundances [ISM], ISM: kinematics and dynamics, STAR-FORMING REGIONS, Physics, Filling factor, LIMITED MILLIMETER SURVEY, INTERSTELLAR JETS, External irradiation, Astronomy and Astrophysics, Ridge (differential geometry), ISM: molecules, MOLECULAR LINE SURVEY, ISM: lines and bands, Delta-v (physics), ODIN SATELLITE, kinematics and dynamics [ISM], Full width at half maximum, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, CLOUD CORES, lines and bands [ISM], EXTRAORDINARY SOURCES ANALYSIS, ISM:lines and bands
Abstract

We present results from a comprehensive submillimeter spectral survey toward the source Orion South, based on data obtained with the Heterodyne Instrument for the Far-Infrared instrument on board the Herschel Space Observatory, covering the frequency range of 480 to 1900 GHz. We detect 685 spectral lines with signal-to-noise ratios (S/Ns) > 3 sigma, originating from 52 different molecular and atomic species. We model each of the detected species assuming conditions of Local Thermodynamic Equilibrium. This analysis provides an estimate of the physical conditions of Orion South (column density, temperature, source size, and VLSR). We find evidence for three different cloud components: a cool (T-ex similar to 20-40 K), spatially extended (> 60 ''), and quiescent (Delta V-FWHM similar to 4 km s(-1)) component; a warmer (T-ex similar to 80-100 K), less spatially extended (similar to 30 ''), and dynamic (Delta V-FWHM similar to 8 km s(-1)) component, which is likely affected by embedded outflows; and a kinematically distinct region (T-ex > 100 K; V-LSR similar to 8 km s(-1)), dominated by emission from species that trace ultraviolet irradiation, likely at the surface of the cloud. We find little evidence for the existence of a chemically distinct "hot-core" component, likely due to the small filling factor of the hot core or hot cores within the Herschel beam. We find that the chemical composition of the gas in the cooler, quiescent component of Orion South more closely resembles that of the quiescent ridge in Orion-KL. The gas in the warmer, dynamic component, however, more closely resembles that of the Compact Ridge and Plateau regions of Orion-KL, suggesting that higher temperatures and shocks also have an influence on the overall chemistry of Orion South.

Published
2016

23. Water and ammonia abundances in S140 with the Odin satellite

Author

A. O. H. Olofsson, Aa. Sandqvist, Carina M. Persson, Marco Spaans, T. Liljestrom, Åke Hjalmarson, D. R. Poelman, John H. Black, Urban Frisk, Michael Olberg, and Astronomy

Subjects
WAVE-ASTRONOMY-SATELLITE, 010504 meteorology & atmospheric sciences, FOS: Physical sciences, Astrophysics, PHOTON-DOMINATED REGION, GAS-PHASE H2O, 1ST DETECTION, MASSIVE PROTOSTARS, MOLECULAR CLOUD, 01 natural sciences, ISM: abundances, Ammonia, chemistry.chemical_compound, Abundance (ecology), 0103 physical sciences, submillimeter, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), 0105 earth and related environmental sciences, Line (formation), Physics, STAR-FORMING REGIONS, SPECTRAL-LINE SURVEY, Astronomy and Astrophysics, line: profiles, Line width, ISM: molecules, ORION-KL, BANDS 486-492, chemistry, Astrophysics - Solar and Stellar Astrophysics, 13. Climate action, Space and Planetary Science, Homogeneous, ISM: individual objects: S140, Outflow, Satellite, line: formation, Intensity (heat transfer)
Abstract

We have used the Odin satellite to obtain strip maps of the ground-state rotational transitions of ortho-water and ortho-ammonia, as well as CO(5-4) and 13CO(5-4) across the PDR, and H218O in the central position. A physi-chemical inhomogeneous PDR model was used to compute the temperature and abundance distributions for water, ammonia and CO. A multi-zone escape probability method then calculated the level populations and intensity distributions. These results are compared to a homogeneous model computed with an enhanced version of the RADEX code. H2O, NH3 and 13CO show emission from an extended PDR with a narrow line width of ~3 kms. Like CO, the water line profile is dominated by outflow emission, however, mainly in the red wing. The PDR model suggests that the water emission mainly arises from the surfaces of optically thick, high density clumps with n(H2)>10^6 cm^-3 and a clump water abundance, with respect to H2, of 5x10^-8. The mean water abundance in the PDR is 5x10^-9, and between ~2x10^-8 -- 2x10^-7 in the outflow derived from a simple two-level approximation. Ammonia is also observed in the extended clumpy PDR, likely from the same high density and warm clumps as water. The average ammonia abundance is about the same as for water: 4x10^-9 and 8x10^-9 given by the PDR model and RADEX, respectively. The similarity of water and ammonia PDR emission is also seen in the almost identical line profiles observed close to the bright rim. Around the central position, ammonia also shows some outflow emission although weaker than water in the red wing. Predictions of the H2O(110-101) and (111-000) antenna temperatures across the PDR are estimated with our PDR model for the forthcoming observations with the Herschel Space Observatory., 13 pages, 14 figures, 10 tables. Accepted for publication in Astronomy & Astrophysics 14 November 2008

Published
2009
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24. Structure analysis of interstellar clouds - II. Applying the Delta-variance method to interstellar turbulence

Author

M. Krips, Volker Ossenkopf, Juergen Stutzki, and Kapteyn Astronomical Institute

Subjects
IRAM KEY-PROJECT, ISM : structure, Continuum (design consultancy), Interstellar cloud, FOS: Physical sciences, methods : data analysis, SMALL-SCALE STRUCTURE, Astrophysics, Power law, ISM : clouds, law.invention, law, CORE, Scaling, methods : statistical, Physics, STAR-FORMING REGIONS, Velocity gradient, Turbulence, MASS-SPECTRA, Molecular cloud, Astrophysics (astro-ph), Astronomy and Astrophysics, Space and Planetary Science, MOLECULAR CLOUDS, Flare
Abstract

The Delta-variance analysis is an efficient tool for measuring the structural scaling behaviour of interstellar turbulence in astronomical maps. In paper I we proposed essential improvements to the Delta-variance analysis. In this paper we apply the improved Delta-variance analysis to i) a hydrodynamic turbulence simulation with prominent density and velocity structures, ii) an observed intensity map of rho Oph with irregular boundaries and variable uncertainties of the different data points, and iii) a map of the turbulent velocity structure in the Polaris Flare affected by the intensity dependence on the centroid velocity determination. The tests confirm the extended capabilities of the improved Delta-variance analysis. Prominent spatial scales were accurately identified and artifacts from a variable reliability of the data were removed. The analysis of the hydrodynamic simulations showed that the injection of a turbulent velocity structure creates the most prominent density structures are produced on a scale somewhat below the injection scale. The new analysis of a rho Oph continuum map reveals an intermediate stage in the molecular cloud evolution showing both signatures of the typical molecular cloud scaling behaviour and the formation of condensed cores. When analysing the velocity structure of the Polaris Flare we show that a universal power law connects scales from 0.03 pc to 3 pc. However, a plateau in the Delta-variance spectrum around 5 pc indicates that the visible large-scale velocity gradient is not converted directly into a turbulent cascade., Comment: Accepted for publication in A&A, Section 6

Published
2008

25. A photon dominated region code comparison study

Author

M. Röllig, N. P. Abel, T. Bell, F. Bensch, J. Black, G. J. Ferland, B. Jonkheid, I. Kamp, M. J. Kaufman, J. Le Bourlot, F. Le Petit, R. Meijerink, O. Morata, V. Ossenkopf, E. Roueff, G. Shaw, M. Spaans, A. Sternberg, J. Stutzki, W.-F. Thi, E. F. van Dishoeck, P. A. M. van Hoof, S. Viti, and M. G. Wolfire

Subjects
Electron density, Photon, Energy balance, methods : numerical, Astrophysics, ISM : clouds, POLYCYCLIC AROMATIC-HYDROCARBONS, H-II REGIONS, Consistency (statistics), 158 MU-M, ISM : general, SMALL-MAGELLANIC-CLOUD, Reference model, Line (formation), NEUTRAL ATOMIC PHASES, STAR-FORMING REGIONS, Physics, astrochemistry, Astronomy and Astrophysics, Observable, ISM : abundances, Computational physics, NONEQUILIBRIUM PHOTODISSOCIATION REGIONS, radiative transfer, INHOMOGENEOUS INTERSTELLAR CLOUDS, Space and Planetary Science, Benchmark (computing), LATE-TYPE GALAXIES, CLUMPY MOLECULAR CLOUDS
Abstract

Aims. We present a comparison between independent computer codes, modeling the physics and chemistry of interstellar photon dominated regions (PDRs). Our goal was to understand the mutual differences in the PDR codes and their effects on the physical and chemical structure of the model clouds, and to converge the output of different codes to a common solution. Methods. A number of benchmark models have been created, covering low and high gas densities n = 10^3, 10^(5.5) cm^(-3) and far ultraviolet intensities χ = 10, 10^5 in units of the Draine field (FUV: 6 < h υ < 13.6 eV). The benchmark models were computed in two ways: one set assuming constant temperatures, thus testing the consistency of the chemical network and photo-processes, and a second set determining the temperature self consistently by solving the thermal balance, thus testing the modeling of the heating and cooling mechanisms accounting for the detailed energy balance throughout the clouds. Results. We investigated the impact of PDR geometry and agreed on the comparison of results from spherical and plane-parallel PDR models. We identified a number of key processes governing the chemical network which have been treated differently in the various codes such as the effect of PAHs on the electron density or the temperature dependence of the dissociation of CO by cosmic ray induced secondary photons, and defined a proper common treatment. We established a comprehensive set of reference models for ongoing and future PDR model bench-marking and were able to increase the agreement in model predictions for all benchmark models significantly. Nevertheless, the remaining spread in the computed observables such as the atomic fine-structure line intensities serves as a warning that there is still a considerable uncertainty when interpreting astronomical data with our models.

Published
2007
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26. Abundances in planetary nebulae

Author

R. Surendiranath, Stuart Pottasch, and Kapteyn Astronomical Institute

Subjects
HII regions, Reflection nebula, Extinction (astronomy), Astrophysics, Photodissociation region, GALACTIC BULGE, PHOTODISSOCIATION REGIONS, Protoplanetary nebula, Emission nebula, EXCITATION, SPECTRA, planetary nebulae : individual : Hb 5, Stellar evolution, Astrophysics::Galaxy Astrophysics, Physics, STAR-FORMING REGIONS, FORBIDDEN LINES, Nebula, Astronomy, Astronomy and Astrophysics, ISM : abundances, Planetary nebula, stars : evolution, Space and Planetary Science, MOLECULAR-HYDROGEN, TRANSITION-PROBABILITIES, MAIN-SEQUENCE NEBULAE, EMISSION
Abstract

The ISO spectra of the bilobal planetary nebula Hb 5 are presented. These spectra are combined with the spectra in the visual wavelength region to obtain a complete, extinction corrected, spectrum. The chemical composition of the nebula is then calculated in several ways. First by directly calculating and adding individual ion abundances, assuming that all the ionic lines are formed in an ionized region surrounding the ionizing star. Secondly by building an "end-to-end model" nebula in which we have included a neutral region and a photodissociation region (PDR) beyond the ionized nebula. In this way we attempt to interpret the molecular hydrogen lines observed by ISO in a more self-consistent way. In the final analysis, the model is found to be basically heuristic, but gives new insights about the PDR and the PN. The implications of these are discussed.

Published
2007
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27. The prominent dust emission feature near 8.9 mu m in four HII regions

Author

A. C. A. Boogert, Alexander G. G. M. Tielens, T. L. Hayward, Louis J. Allamandola, and Els Peeters

Subjects
H II region, HII regions, infrared : ISM, Infrared, Polycyclic aromatic hydrocarbon, Astrophysics, Spatial distribution, MOLECULAR CLOUD, Spectral line, POLYCYCLIC AROMATIC-HYDROCARBONS, ISM : molecules, H-II REGIONS, Cosmic dust, chemistry.chemical_classification, Physics, STAR-FORMING REGIONS, Molecular cloud, Astronomy and Astrophysics, Plasma, FAR-INFRARED OBSERVATIONS, HIGH-ANGULAR RESOLUTION, chemistry, Space and Planetary Science, RADIO RECOMBINATION LINE, METHANOL MASER SURVEY, ISM : lines and bands, INTERSTELLAR DUST, MASSIVE STARS
Abstract

We present a mid-infrared study of four H II regions based on the combination of Infrared Space Observatory (ISO) SWS observations with spatial information from SpectroCam-10 images and long-slit spectra. We report a prominent broad emission feature near 8.9 mum. The peak position and width of this feature do not resemble known polycyclic aromatic hydrocarbon ( PAH) or dust emission features. Its spatial distribution is analyzed for two H II regions and is clearly distinct from that of the PAH emission features, being more similar to that of the ionized gas and especially to the spatial distribution of the dust continuum at 15 mum. Thus, the carrier of this band likely resides within the H II region. Possible carriers of this feature are highlighted.

Published
2005

28. Near-IR speckle imaging of massive young stellar objects

Author

C. Alvarez, Andrea Richichi, Melvin Hoare, and Andreas Glindemann

Subjects
Reflection nebula, T-TAURI STARS, Astrophysics::High Energy Astrophysical Phenomena, Young stellar object, stars : winds, INFRARED REFLECTION NEBULA, FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, outflows, Speckle pattern, techniques : high angular resolution, LKH-ALPHA 101, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Galaxy Astrophysics, infrared : stars, STAR-FORMING REGIONS, Physics, Nebula, stars : formation, scattering, Astrophysics (astro-ph), GHZ METHANOL MASERS, Astronomy and Astrophysics, Conical surface, NGC 2264, H-II-REGIONS, Space and Planetary Science, RADIO-EMISSION, HERBIG-AE/BE STARS, Reflection (physics), Outflow, Astrophysics::Earth and Planetary Astrophysics, Speckle imaging, S235 MOLECULAR CLOUD, reflection nebulae
Abstract

We present near-IR speckle images of 21 massive Young Stellar Objects (YSOs) associated with outflows. The aim of this study is to search for sub-arcsecond reflection nebulae associated with the outflow cavity. We find that 6 of the massive YSOs show a conical nebula which can be interpreted in terms of reflected light from the dusty walls of the outflow cavity. In all cases, the small scale structures seen in our images are compared with outflow indicators found in the literature. No clear correlation is found between the presence of the reflection nebulosity and any property such as degree of embeddedness. We also note that 3 of the sources show close companions, one of them belonging also to the sample with conical nebula., Comment: 17 pages, 16 figures, accepted for publication in A&A

Published
2004
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29. Search for solid HDO in low-mass protostars

Author

Emmanuel Caux, Theodore Simon, Alexander G. G. M. Tielens, Berengere Parise, Cecilia Ceccarelli, Emmanuel Dartois, John Rayner, and Astronomy

Subjects
Formaldehyde, Analytical chemistry, FOS: Physical sciences, Astrophysics, Fractionation, Gas phase, IRAS 16293-2422, chemistry.chemical_compound, DOUBLY DEUTERATED FORMALDEHYDE, L1489 IRS, Protostar, TMR1, molecules, lines and bands, QB, Physics, STAR-FORMING REGIONS, SVS13, individual objects : NGC 1333 SVS12, SVS13, L1489 IRS, TMR1, astrochemistry, stars : formation, Astrophysics (astro-ph), Astronomy and Astrophysics, ISM : abundances, molecules, lines and bands, ISM : abundances, YOUNG STELLAR OBJECTS, GRAIN SURFACE-CHEMISTRY, individual objects : NGC 1333 SVS12, HOT CORE, DEUTERIUM FRACTIONATION, chemistry, Deuterium, Space and Planetary Science, COMPACT RIDGE, Methanol, Low Mass, MOLECULAR OUTFLOWS, HIGH-RESOLUTION
Abstract

We present ground-based 2.1 to 4.2 microns observations of four low-mass protostars. We searched for the 4.1 microns OD stretch band, characteristic of solid HDO in grain mantles. We did not detect solid HDO in any of the four sources, but we derive 3-sigma upper limits from 0.5% to 2% for the HDO/H2O ratio depending on the source. These ratios provide strong constraints to solid-state deuteration models when compared to deuterium fractionation values observed in the gas phase. We discuss various scenarios that could lead to such a low water deuteration compared to the high formaldehyde and methanol deuteration observed in the gas phase., 8 pages, 6 figures Accepted for publication in A&A

Published
2003
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30. The Hot Core around the Low-Mass Protostar IRAS 16293-2422: Scoundrels Rule!

Author

Alain Castets, David Teyssier, Cecilia Ceccarelli, Berengere Parise, Emmanuel Caux, Valentine Wakelam, Stéphanie Cazaux, A. G. G. M. Tielens, and Kapteyn Astronomical Institute

Subjects
Methyl formate, Formic acid, LINE EMISSION, Young stellar object, Cyanide, Astrophysics, Propyne, IRAS 16293-2422, ISM : molecules, MOLECULES, chemistry.chemical_compound, Protostar, FORMALDEHYDE, Dimethyl ether, ACETIC-ACID, STAR-FORMING REGIONS, Physics, stars : formation, Star formation, Astronomy and Astrophysics, ISM : abundances, GRAIN SURFACE-CHEMISTRY, YOUNG STELLAR OBJECTS, ISM : individual (IRAS 16293-2422), ENVELOPES, chemistry, Space and Planetary Science, SUBMILLIMETER
Abstract

While warm dense gas is prevalent around low-mass protostars, the presence of complex saturated molecules-the chemical inventory characteristic of hot cores-has remained elusive in such environments. Here we report the results of an IRAM 30 m study of the molecular composition associated with the low-mass protostar IRAS 16293-2422. Our observations highlight an extremely rich organic inventory in this source with abundant amounts of complex O- and N-bearing molecules such as formic acid, HCOOH, acetaldehyde, CH3CHO, methyl formate, CH3OCHO, dimethyl ether, CH3OCH3, acetic acid, CH3COOH, methyl cyanide, CH3CN, ethyl cyanide, C2H5CN, and propyne, CH3CCH. We compare the composition of the hot core around this low-mass young stellar object with those around massive protostars and address the chemical processes involved in molecular complexity in regions of star formation.

Published
2003
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31. The HIFI spectral survey of AFGL 2591 (CHESS). I. Highly excited linear rotor molecules in the high-mass protostellar envelope

Author

Cecilia Ceccarelli, M. H. D. van der Wiel, M. Kazmierczak, F. F. S. van der Tak, Laurent Pagani, 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), SRON Netherlands Institute for Space Research (SRON), Institut de Planétologie et d'Astrophysique de Grenoble (IPAG ), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-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 Joseph Fourier - Grenoble 1 (UJF)-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)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), École normale supérieure - Paris (ENS-PSL), Kapteyn Astronomical Institute, and Astronomy

Subjects
ROTATIONAL-EXCITATION, 010504 meteorology & atmospheric sciences, FOS: Physical sciences, Astrophysics, CYGNUS-X, 01 natural sciences, ISM: clouds, Spectral line, Atmospheric radiative transfer codes, CHEMISTRY, 0103 physical sciences, AFGL-2591, OUTFLOW, 010303 astronomy & astrophysics, Optical depth, Solar and Stellar Astrophysics (astro-ph.SR), ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Envelope (waves), Line (formation), Physics, STAR-FORMING REGIONS, [PHYS]Physics [physics], stars: formation, astrochemistry, Astronomy and Astrophysics, YOUNG STELLAR OBJECTS, Astrophysics - Astrophysics of Galaxies, Redshift, ISM: molecules, CO, Astrophysics - Solar and Stellar Astrophysics, 13. Climate action, Space and Planetary Science, GL-2591, Excited state, Astrophysics of Galaxies (astro-ph.GA), Outflow, ISM: individual objects: AFGL 2591, EMISSION, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

We aim to reveal the gas energetics in the circumstellar environment of the prototypical high-mass protostellar object AFGL2591 using space-based far-infrared observations of linear rotor molecules. Rotational spectral line signatures of CO, HCO+, CS, HCN and HNC from a 490-1240 GHz survey with Herschel/HIFI, complemented by ground-based JCMT and IRAM 30m spectra, cover transitions with E(up)/k between 5 and ~300 K (750K for 12C16O, using selected frequency settings up to 1850 GHz). The resolved spectral line profiles are used to separate and study various kinematic components. The line profiles show two emission components, the widest and bluest of which is attributed to an approaching outflow and the other to the envelope. We find evidence for progressively more redshifted and wider line profiles from the envelope gas with increasing energy level, qualitatively explained by residual outflow contribution picked up in the systematically decreasing beam size. Integrated line intensities for each species decrease as E(up)/k increases from 150 K for all species. This indicates that warm gas should be added to the model and that the model's geometry should provide low optical depth pathways for line emission from this warm gas to escape, for example in the form of UV heated outflow cavity walls viewed at a favorable inclination angle. Physical and chemical conditions derived for the outflow gas are similar to those in the protostellar envelope, possibly indicating that the modest velocity (, Accepted for publication in A&A; 16 pages, 8 figures, 4 tables

Published
2013
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32. Misalignment of magnetic fields and outflows in protostellar cores

Author

Alberto D. Bolatto, Charles L. H. Hull, John E. Vaillancourt, Richard L. Plambeck, Jason Fiege, Geoffrey C. Bower, Katherine Jameson, John M. Carpenter, Richard M. Crutcher, Nicholas S. Hakobian, Brenda C. Matthews, Thushara Pillai, Melvyn Wright, Lee G. Mundy, Nikolaus H. Volgenau, Erica Franzmann, Ian W. Stephens, A. Meredith Hughes, Martin Houde, James W. Lamb, Woojin Kwon, Carl Heiles, Leslie W. Looney, John J. Tobin, and Marc W. Pound

Subjects
010504 meteorology & atmospheric sciences, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, DUST POLARIZATION, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, magnetic fields, MOLECULAR CLOUD, 01 natural sciences, ORION, 0103 physical sciences, Perpendicular, Protostar, Astrophysics::Solar and Stellar Astrophysics, 010303 astronomy & astrophysics, MILLIMETER, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences, Physics, STAR-FORMING REGIONS, polarization, stars: formation, stars: protostars, DISK FORMATION, stars: magnetic field, Astronomy and Astrophysics, Polarization (waves), Astrophysics - Astrophysics of Galaxies, Circumstellar disk, H2O MASERS, Magnetic field, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), DISTANCE, ISM: magnetic fields, Astrophysics::Earth and Planetary Astrophysics, T-TAURI, VLBA DETERMINATION
Abstract

We present results of 1.3 mm dust polarization observations toward 16 nearby, low-mass protostars, mapped with ~2.5" resolution at CARMA. The results show that magnetic fields in protostellar cores on scales of ~1000 AU are not tightly aligned with outflows from the protostars. Rather, the data are consistent with scenarios where outflows and magnetic fields are preferentially misaligned (perpendicular), or where they are randomly aligned. If one assumes that outflows emerge along the rotation axes of circumstellar disks, and that the outflows have not disrupted the fields in the surrounding material, then our results imply that the disks are not aligned with the fields in the cores from which they formed., Comment: 6 pages, 2 figures, 1 table

Published
2013

33. Herschel/SPIRE Sub-millimeter Spectra of Local Active Galaxies

Author

Naseem Rangwala, Julia Kamenetzky, Miguel Pereira-Santaella, Christine D. Wilson, Asantha Cooray, Maarten Baes, Maximilien R. P. Schirm, Diane Cormier, M. J. Barlow, Jason Glenn, Kate Gudrun Isaak, Gemma Busquet, Alessandro Boselli, Luigi Spinoglio, 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
GALACTIC NUCLEI, Active galactic nucleus, Cosmology and Nongalactic Astrophysics (astro-ph.CO), 010504 meteorology & atmospheric sciences, nuclei [galaxies], MU-M, FOS: Physical sciences, Astrophysics, 01 natural sciences, Spectral line, Seyfert [galaxies], 0103 physical sciences, Radiative transfer, ATOMIC CARBON, Emission spectrum, 010303 astronomy & astrophysics, Collisional excitation, 0105 earth and related environmental sciences, Line (formation), Physics, STAR-FORMING REGIONS, XMM-NEWTON, ISM [galaxies], [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], Astronomy and Astrophysics, LUMINOUS INFRARED GALAXIES, Astrophysics - Astrophysics of Galaxies, Galaxy, MOLECULAR GAS, Spire, Physics and Astronomy, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), active [galaxies], NEARBY SEYFERT-GALAXIES, BLACK-HOLE MASS, HIGH-RESOLUTION SPECTROSCOPY, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

We present the sub-millimeter spectra from 450 GHz to 1550 GHz of eleven nearby active galaxies observed with the SPIRE Fourier Transform Spectrometer (SPIRE/FTS) onboard Herschel. We detect CO transitions from J_up = 4 to 12, as well as the two [CI] fine structure lines at 492 and 809 GHz and the [NII] 461 GHz line. We used radiative transfer models to analyze the observed CO spectral line energy distributions (SLEDs). The FTS CO data were complemented with ground-based observations of the low-J CO lines. We found that the warm molecular gas traced by the mid-J CO transitions has similar physical conditions (n_H2 ~ 10^3.2 - 10^3.9 cm^-3 and T_kin ~ 300 - 800 K) in most of our galaxies. Furthermore, we found that this warm gas is likely producing the mid-IR rotational H2 emission. We could not determine the specific heating mechanism of the warm gas, however it is possibly related to the star-formation activity in these galaxies. Our modeling of the [CI] emission suggests that it is produced in cold (T_kin < 30 K) and dense (n_H2 > 10^3 cm^-3) molecular gas. Transitions of other molecules are often detected in our SPIRE/FTS spectra. The HF J=1-0 transition at 1232 GHz is detected in absorption in UGC05101 and in emission in NGC7130. In the latter, near-infrared pumping, chemical pumping, or collisional excitation with electrons are plausible excitation mechanisms likely related to the AGN of this galaxy. In some galaxies few H2O emission lines are present. Additionally, three OH+ lines at 909, 971, and 1033 GHz are identified in NGC7130., Accepted for publication in ApJ; 20 pages, 9 figures

Published
2013
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34. The chemistry of ions in the Orion Bar I. – CH + , SH + , and CF +. The effect of high electron density and vibrationally excited H2 in a warm PDR surface

Author

E. A. Bergin, F. F. S. van der Tak, Z. Nagy, Volker Ossenkopf, Maryvonne Gerin, F. Le Petit, C. Joblin, J. R. Goicoechea, John H. Black, J. Le Bourlot, M. Roellig, Institut de génétique et biologie moléculaire et cellulaire (IGBMC), Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Université Louis Pasteur - Strasbourg I, SRON Netherlands Institute for Space Research (SRON), 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), 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), Laboratoire Univers et Théories (LUTH (UMR_8102)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Centre d'étude spatiale des rayonnements (CESR), 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)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées, Physikalisches Institut [Köln], Universität zu Köln, Department of Astronomy [Ann Arbor], University of Michigan [Ann Arbor], University of Michigan System-University of Michigan System, Université Louis Pasteur - Strasbourg I-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), École normale supérieure - Paris (ENS-PSL), 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), 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), Universität zu Köln = University of Cologne, bibliotheque, la., Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-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), and Astronomy

Subjects
ROTATIONAL-EXCITATION, ISM: individual objects: Orion Bar, DATABASE, Analytical chemistry, FOS: Physical sciences, LINES, Electron, Astrophysics, 01 natural sciences, Ion, [PHYS] Physics [physics], PHOTON-DOMINATED REGIONS, 0103 physical sciences, Radiative transfer, ABSORPTION, 010306 general physics, 010303 astronomy & astrophysics, Hyperfine structure, ComputingMilieux_MISCELLANEOUS, Line (formation), Physics, STAR-FORMING REGIONS, [PHYS]Physics [physics], PHOTODISSOCIATION REGION, INTERSTELLAR-MEDIUM, Astronomy and Astrophysics, Astrophysics - Astrophysics of Galaxies, DIFFUSE CLOUDS, ISM: molecules, 3. Good health, 13. Climate action, Space and Planetary Science, Excited state, Astrophysics of Galaxies (astro-ph.GA), [PHYS.ASTR] Physics [physics]/Astrophysics [astro-ph], EMISSION, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Excitation, Bar (unit)
Abstract

The abundances of interstellar CH+ and SH+ are not well understood as their most likely formation channels are highly endothermic. Using data from Herschel, we study the formation of CH+ and SH+ in a typical high UV-illumination photon-dominated region (PDR), the Orion Bar. Herschel/HIFI provides velocity-resolved data of CH+ 1-0 and 2-1 and three hyperfine transitions of SH+. Herschel/PACS provides information on the excitation and spatial distribution of CH+ (up to J=6-5). The widths of the CH+ 2-1 and 1-0 transitions are of ~5 km/s, significantly broader than the typical width of dense gas tracers in the Orion Bar (2-3 km/s) and are comparable to the width of tracers of the interclump medium such as C+ and HF. The detected SH+ transitions are narrower compared to CH+ and have line widths of 3 km/s, indicating that SH+ emission mainly originates in denser condensations. Non-LTE radiative transfer models show that electron collisions affect the excitation of CH+ and SH+, and that reactive collisions need to be taken into account to calculate the excitation of CH+. Comparison to PDR models shows that CH+ and SH+ are tracers of the warm surface region (AV, Accepted for publication in A&A, 12 pages, 11 figures, abstract shortened

Published
2013
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35. The Spatial Distribution of Organics toward the High-Mass YSO NGC 7538 IRS9

Author

Edith C. Fayolle, Karin I. Öberg, Claudia Cyganowski, Robin T. Garrod, Floris van der Tak, Mavis D. Boamah, and Astronomy

Subjects
010504 meteorology & atmospheric sciences, Young stellar object, Evaporation, LINE SURVEY, Flux, FOS: Physical sciences, Astrophysics, Spatial distribution, circumstellar matter, 7. Clean energy, 01 natural sciences, Submillimeter Array, HOT CORES, YOUNG STARS, 0103 physical sciences, Protostar, Molecule, 14. Life underwater, ISM: individual objects (NGC 7538 IRS9), 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, Envelope (waves), STAR-FORMING REGIONS, BIPOLAR MOLECULAR OUTFLOWS, Physics, stars: formation, astrochemistry, PROTOSTARS, Astronomy and Astrophysics, Astrophysics - Astrophysics of Galaxies, COMPLEX CHEMISTRY, stars: massive, molecular processes, METHANOL MASERS, 13. Climate action, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), CHEMICAL-MODEL, NGC-7538 IRS-9
Abstract

Based on astrochemical theory, the complex molecular composition around high-mass YSOs should evolve from the outer envelope in toward the central hot region as a sequence of temperature dependent chemical pathways are activated in ices and in the gas-phase. The resulting complex molecules have been broadly classified into three generations dependent on the temperature (25, and >100 K) required for formation. We combine IRAM 30m and Submillimeter Array observations to explore the spatial distribution of organic molecules around the high-mass young stellar object NGC 7538 IRS9, whose weak complex molecule emission previously escaped detection, quantifying the emission and abundance profiles of key organic molecules as a function of distance from the central protostar. We find that emission from N-bearing organics and saturated O-bearing organics present large increases in emission around 8000 AU and R, Accepted for publication in ApJ. 33 pages including 15 figures

Published
2013
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36. A study of deuterated water in the low-mass protostar IRAS16293-2422

Author

Audrey Coutens, Sandrine Bottinelli, Yohann Scribano, Emmanuel Caux, Claudine Kahane, Charlotte Vastel, Alexandre Faure, Cecilia Ceccarelli, Laurent Wiesenfeld, Institut de Planétologie et d'Astrophysique de Grenoble (IPAG ), Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-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 Joseph Fourier - Grenoble 1 (UJF)-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), Univ Toulouse UPS, Ctr Etud Spatiale Rayonnements, F-31062 Toulouse 9, France, Centre Etud Spatiale Rayonnements Toulouse, CNRS INSU, UMR 5187, F-31028 Toulouse 4, France, UMR 5187 Toulouse, Centre d'étude spatiale des rayonnements (CESR), 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)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées, Laboratoire Interdisciplinaire Carnot de Bourgogne (LICB), Université de Bourgogne (UB)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Astrophysique de Grenoble ( LAOG ), Université Joseph Fourier - Grenoble 1 ( UJF ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ), Institut de Planétologie et d'Astrophysique de Grenoble ( IPAG ), Observatoire des Sciences de l'Univers de Grenoble ( OSUG ), 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 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 ) -Centre National de la Recherche Scientifique ( CNRS ), Centre d'étude spatiale des rayonnements ( CESR ), Université Paul Sabatier - Toulouse 3 ( UPS ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Observatoire Midi-Pyrénées ( OMP ) -Centre National de la Recherche Scientifique ( CNRS ), Laboratoire Interdisciplinaire Carnot de Bourgogne ( LICB ), Université de Bourgogne ( UB ) -Centre National de la Recherche Scientifique ( CNRS ), Laboratoire d'Astrophysique de Grenoble (LAOG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-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), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-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 Joseph Fourier - Grenoble 1 (UJF)-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)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), 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), and Laboratoire Interdisciplinaire Carnot de Bourgogne (ICB)

Subjects
010504 meteorology & atmospheric sciences, Absorption spectroscopy, LINE EMISSION, FOS: Physical sciences, Astrophysics, INTERSTELLAR HEAVY-WATER, 01 natural sciences, 7. Clean energy, COLOGNE DATABASE, SPECTRAL SURVEYS, SUBMILLIMETER ARRAY, 0103 physical sciences, CO DEPLETION, Radiative transfer, Protostar, HERSCHEL-HIFI, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, Line (formation), Physics, STAR-FORMING REGIONS, Star formation, Molecular cloud, Astronomy and Astrophysics, Astrophysics - Astrophysics of Galaxies, HOT CORE, Deuterium, 13. Climate action, Space and Planetary Science, [SDU]Sciences of the Universe [physics], Astrophysics of Galaxies (astro-ph.GA), MOLECULAR CLOUDS, Low Mass
Abstract

The HDO/H2O ratio is a powerful diagnostic to understand the evolution of water from the first stages of star formation to the formation of planets and comets. Our aim is to determine precisely the abundance distribution of HDO towards the low-mass protostar IRAS16293-2422 and learn more about the water formation mechanisms by determining the HDO/H2O abundance ratio. A spectral survey of the source IRAS16293-2422 was carried out in the framework of the CHESS Herschel Key program with the HIFI instrument, allowing the detection of numerous HDO lines. Other transitions have been observed previously with ground-based telescopes. The spherical Monte Carlo radiative transfer code RATRAN was used to reproduce the observed line profiles of HDO by assuming an abundance jump. To determine the H2O abundance throughout the envelope, a similar study was made of the H2-18O observed lines, as the H2O main isotope lines are contaminated by the outflows. We derive an inner HDO abundance of 1.7e-7 and an outer HDO abundance of 8e-11. To reproduce the HDO absorption lines, it is necessary to add an absorbing layer in front of the envelope. It may correspond to a water-rich layer created by the photodesorption of the ices at the edges of the molecular cloud. The HDO/H2O ratio is ~1.4-5.8% in the hot corino whereas it is ~0.2-2.2% in the outer envelope. It is estimated at ~4.8% in the added absorbing layer. Although it is clearly higher than the cosmic D/H abundance, the HDO/H2O ratio remains lower than the D/H ratio derived for other deuterated molecules observed in the same source. The similarity of the ratios derived in the hot corino and in the added absorbing layer suggests that water formed before the gravitational collapse of the protostar, contrary to formaldehyde and methanol, which formed later once the CO molecules had depleted on the grains., Comment: 12 pages, 11 figures

Published
2012
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37. The massive protostar W43-MM1 as seen by Herschel-HIFI water spectra: high turbulence and accretion luminosity

Author

L. Chavarria, Sylvain Bontemps, T. Jacq, Friedrich Wyrowski, Jonathan Braine, Lars E. Kristensen, Fabrice Herpin, Alain Baudry, E. F. van Dishoeck, F. F. S. van der Tak, FORMATION STELLAIRE 2012, 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)-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), Institut de Planétologie et d'Astrophysique de Grenoble (IPAG ), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-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)-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)-Université Joseph Fourier - Grenoble 1 (UJF)-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)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Max-Planck-Institut für Radioastronomie (MPIFR), Max-Planck-Institut für Extraterrestrische Physik (MPE), Leiden Observatory [Leiden], Universiteit Leiden [Leiden], and European Southern Observatory (ESO)

Subjects
FOS: Physical sciences, Astrophysics, ENERGY-DISTRIBUTIONS, 01 natural sciences, 7. Clean energy, Spectral line, ISM: abundances, H-II REGIONS, NGC 1333, 0103 physical sciences, Protostar, Supersonic speed, 010306 general physics, 2-DIMENSIONAL RADIATIVE-TRANSFER, 010303 astronomy & astrophysics, Physics, STAR-FORMING REGIONS, stars: formation, stars: protostars, INTERSTELLAR-MEDIUM, Turbulence, [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Astronomy and Astrophysics, line: profiles, CIRCUMSTELLAR ENVIRONMENT, stars: early-type, MOLECULAR LINES, YOUNG STELLAR OBJECTS, [PHYS.ASTR.SR]Physics [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Astrophysics - Astrophysics of Galaxies, Accretion (astrophysics), ISM: molecules, Radiation pressure, 13. Climate action, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), Spectral energy distribution, CLOUD CORES, Outflow, Galaxy Astrophysics
Abstract

We present Herschel/HIFI observations of fourteen water lines in W43-MM1, a massive protostellar object in the luminous star cluster-forming region W43. We analyze the gas dynamics from the line profiles using Herschel-HIFI observations (WISH-KP) of fourteen far-IR water lines (H2O, H217O, H218O), CS(11-10), and C18O(9-8) lines, and using our modeling of the continuum spectral energy distribution. As for lower mass protostellar objects, the molecular line profiles are a mix of emission and absorption, and can be decomposed into 'medium', and 'broad' velocity components. The broad component is the outflow associated with protostars of all masses. Our modeling shows that the remainder of the water profiles can be well fitted by an infalling and passively heated envelope, with highly supersonic turbulence varying from 2.2 km/s in the inner region to 3.5 km/s in the outer envelope. Also, W43-MM1 has a high accretion rate, between 4.0 x 10^{-4} and 4.0 x 10^{-2} \msun /yr, derived from the fast (0.4-2.9 km/s) infall observed. We estimate a lower mass limit of gaseous water of 0.11 \msun and total water luminosity of 1.5 \lsun (in the 14 lines presented here). The central hot core is detected with a water abundance of 1.4 x 10^{-4} while the water abundance for the outer envelope is 8 x10^{-8}. The latter value is higher than in other sources, most likely related to the high turbulence and the micro-shocks created by its dissipation. Examining water lines of various energies, we find that the turbulent velocity increases with the distance to the center. While not in clear disagreement with the competitive accretion scenario, this behavior is predicted by the turbulent core model. Moreover, the estimated accretion rate is high enough to overcome the expected radiation pressure., Accepted in A&A on April 2, 2012. 12 pages 7 figures

Published
2012
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38. Herschel/HIFI detections of hydrides towards AFGL 2591. Envelope emission versus tenuous cloud absorption [Letter]

Author

Javier R. Goicoechea, M. Tafalla, Pierre Encrenaz, P. Stäuber, Jes K. Jørgensen, Jonathan Braine, T. Giannini, Laurent Pagani, Steven D. Doty, Alain Baudry, Michael Olberg, Rafael Bachiller, M. Marseille, Th. de Graauw, E. F. van Dishoeck, Lars E. Kristensen, R. Schieder, José Cernicharo, André Csillaghy, S. Bruderer, S. F. Wampfler, T. A. van Kempen, Paolo Saraceno, Arnold O. Benz, Gary J. Melnick, David A. Neufeld, T. Jacq, C. Dedes, J. Santiago-Garcia, N. Honingh, John C. Pearson, R. Shipman, Frank Helmich, D. Teyssier, M. Fich, A. Di Giorgio, Willem Jellema, Edwin Bergin, Per Bjerkeli, N. Whyborn, Paola Caselli, R. Plume, Ruud Visser, Dariusz C. Lis, M. Melchior, Fabrice Herpin, Christophe Risacher, B. Larsson, Emmanuel Caux, Brunella Nisini, C. McCoey, Christian Monstein, F. Daniel, Geoffrey A. Blake, Doug Johnstone, Gregory J. Herczeg, Umut A. Yildiz, Berengere Parise, Claudio Codella, Sylvain Bontemps, René Liseau, Milena Benedettini, Michiel R. Hogerheijde, Friedrich Wyrowski, Carsten Dominik, F. F. S. van der Tak, W. Bächtold, Asunción Fuente, Low Energy Astrophysics (API, FNWI), Laboratoire d'Astrophysique de Grenoble (LAOG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - 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-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), Herschel Science Center [Madrid], European Space Astronomy Centre (ESAC), Agence Spatiale Européenne = European Space Agency (ESA)-Agence Spatiale Européenne = European Space Agency (ESA), Centre d'étude spatiale des rayonnements (CESR), 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), 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), Observatoire aquitain des sciences de l'univers (OASU), 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), Laboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux (L3AB), Laboratoire Optimisation de la Conception et Ingénierie de l'Environnement (LOCIE), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), INAF - Osservatorio Astrofisico di Arcetri (OAA), Istituto Nazionale di Astrofisica (INAF), Centro de Investigaciones Biológicas (CSIC), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Astronomical Institute Anton Pannekoek (AI PANNEKOEK), University of Amsterdam [Amsterdam] (UvA), SRON Netherlands Institute for Space Research (SRON), INAF - Osservatorio Astronomico di Roma (OAR), Onsala Space Observatory, Chalmers University of Technology [Göteborg], ESO, European Southern Observatory (ESO), Istituto di Fisica dello Spazio Interplanetario (IFSI), National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), Max-Planck-Institut für Radioastronomie (MPIFR), École normale supérieure - Paris (ENS Paris), European Space Agency (ESA)-European Space Agency (ESA), 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)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées, 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, and Consiglio Nazionale delle Ricerche (CNR)

Subjects
Photon, FOS: Physical sciences, Astrophysics, 7. Clean energy, Far infrared, CHEMISTRY, EXCITATION, OUTFLOW, Solar and Stellar Astrophysics, Spectral resolution, H2O+, Absorption (electromagnetic radiation), Solar and Stellar Astrophysics (astro-ph.SR), Envelope (waves), QB, STAR-FORMING REGIONS, Physics, stars: formation, SPECTROSCOPY, INTERSTELLAR-MEDIUM, astrochemistry, [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Astronomy and Astrophysics, [PHYS.ASTR.SR]Physics [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Diatomic molecule, ISM: molecules, Astrophysics - Solar and Stellar Astrophysics, GL-2591, 13. Climate action, Space and Planetary Science, ABUNDANCE, Outflow, ISM: individual objects: AFGL 2591, Excitation
Abstract

The Heterodyne Instrument for the Far Infrared (HIFI) onboard the Herschel Space Observatory allows the first observations of light diatomic molecules at high spectral resolution and in multiple transitions. Here, we report deep integrations using HIFI in different lines of hydrides towards the high-mass star forming region AFGL 2591. Detected are CH, CH+, NH, OH+, H2O+, while NH+ and SH+ have not been detected. All molecules except for CH and CH+ are seen in absorption with low excitation temperatures and at velocities different from the systemic velocity of the protostellar envelope. Surprisingly, the CH(JF,P = 3/2_2,- - 1/2_1,+) and CH+(J = 1 - 0, J = 2 - 1) lines are detected in emission at the systemic velocity. We can assign the absorption features to a foreground cloud and an outflow lobe, while the CH and CH+ emission stems from the envelope. The observed abundance and excitation of CH and CH+ can be explained in the scenario of FUV irradiated outflow walls, where a cavity etched out by the outflow allows protostellar FUV photons to irradiate and heat the envelope at larger distances driving the chemical reactions that produce these molecules., Comment: Accepted for publication in Astronomy and Astrophysics (HIFI first results issue)

Published
2010
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39. First detection of ND in the solar-mass protostar IRAS16293-2422

Author

O. Coeur-Joly, Dariusz C. Lis, A. Baudry, Karine Demyk, W. D. Langer, Carsten Dominik, Adam Walters, Friedrich Wyrowski, K. F. Schuster, Gary J. Melnick, A. Lorenzani, M. Salez, David A. Neufeld, Paolo Saraceno, Paola Caselli, P. F. Goldsmith, Sébastien Maret, Audrey Coutens, Geoffrey A. Blake, M. H. D. van der Wiel, Bertrand Lefloch, C. Comito, S. D. Lord, Arnold O. Benz, S. Cabrit, L. Ravera, Thomas G. Phillips, C. Codella, Berengere Parise, Emmanuel Caux, Peter Schilke, P. Hily-Blant, Laurent Pagani, Valentine Wakelam, Alain Castets, Brunella Nisini, John E. Pearson, N. Crimier, Maryvonne Gerin, Claudine Kahane, Frank Helmich, E. Falgarone, T. Jacq, Aurore Bacmann, Patrick Hennebelle, F. F. S. van der Tak, T. A. Bell, M. Benedettini, H. W. Yorke, A. Klotz, Asunción Fuente, José Cernicharo, Charlotte Vastel, Th. Henning, Mihkel Kama, Adwin Boogert, Cecilia Ceccarelli, P. J. Encrenaz, S. Pacheco, Rolf Guesten, Aggm Tielens, E. A. Bergin, Serena Viti, A. Faure, A. Cros, Sandrine Bottinelli, Eric Herbst, FORMATION STELLAIRE 2010, Laboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux (L3AB), 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), 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), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Bordeaux (UB), Laboratoire d'Astrophysique de Grenoble (LAOG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Centre d'étude spatiale des rayonnements (CESR), 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), CNRS INSU, UMR 5187, F-31028 Toulouse 4, France, UMR 5187 Toulouse, 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), Centro de Astrobiologia [Madrid] (CAB), Instituto Nacional de Técnica Aeroespacial (INTA)-Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Max-Planck-Institut für Astronomie (MPIA), Max-Planck-Gesellschaft, Department of Astronomy [Ann Arbor], University of Michigan [Ann Arbor], University of Michigan System-University of Michigan System, Laboratoire Optimisation de la Conception et Ingénierie de l'Environnement (LOCIE), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Astronomical Institute Anton Pannekoek (AI PANNEKOEK), University of Amsterdam [Amsterdam] (UvA), Laboratoire de Radioastronomie (LRA), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Observatoire de Haute-Provence (OHP), Institut Pythéas (OSU PYTHEAS), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Centre National de la Recherche Scientifique (CNRS), I. Physikalisches Institut [Köln], Universität zu Köln = University of Cologne, Max Planck Institute for Radio Astronomy, AMOR 2010, INAF - Osservatorio Astrofisico di Arcetri (OAA), Istituto Nazionale di Astrofisica (INAF), Ohio State Univ, Dept Phys, Columbus, OH 43210 USA, Ohio State University [Columbus] (OSU), Ohio State Univ, Dept Astron & Chem, Columbus, OH 43210 USA, INAF - Osservatorio Astronomico di Roma (OAR), Istituto di Fisica dello Spazio Interplanetario (IFSI), National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), Kapteyn Astronomical Institute [Groningen], University of Groningen [Groningen], SRON Netherlands Institute for Space Research (SRON), Max-Planck-Institut für Radioastronomie (MPIFR), Interactions et dynamique des environnements de surface (IDES), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Astronomy, Kapteyn Astronomical Institute, 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), Univ Toulouse UPS, Ctr Etud Spatiale Rayonnements, F-31062 Toulouse 9, France, Centre Etud Spatiale Rayonnements Toulouse, Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-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, PSL Research University (PSL)-PSL Research University (PSL)-Université de Cergy Pontoise (UCP), Ctr Astrobiol CSIC INTA, Lab Astrofis Mol, Madrid 28850, Spain, Ctr Astrobiol CSIC INTA, Lab Astrofis Mol, Madrid, Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Univ Cologne, Inst Phys 1, D-50937 Cologne, Germany, Univ Cologne, Inst Phys 1, Osservatorio di Astrofisica di Roma (OAR), Consiglio Nazionale delle Ricerche (CNR), Low Energy Astrophysics (API, FNWI), 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)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées, École normale supérieure - Paris (ENS Paris), Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Institut de Recherche pour le Développement (IRD), and Universität zu Köln

Subjects
010504 meteorology & atmospheric sciences, Radical, Astronomy, Analytical chemistry, FOS: Physical sciences, Astrophysics, Fractionation, 01 natural sciences, COLOGNE DATABASE, Ion, DOUBLY DEUTERATED FORMALDEHYDE, 0103 physical sciences, Molecule, Protostar, 010303 astronomy & astrophysics, Hyperfine structure, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, QB, Physics, STAR-FORMING REGIONS, Solar mass, AMMONIA, CDMS, stars: formation, Research Programm of Institute for Mathematics, Astrophysics and Particle Physics, CORES, Astronomy and Astrophysics, Astrophysics - Astrophysics of Galaxies, ISM: molecules, DEUTERIUM FRACTIONATION, [PHYS.ASTR.GA]Physics [physics]/Astrophysics [astro-ph]/Galactic Astrophysics [astro-ph.GA], Deuterium, 13. Climate action, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), MOLECULAR-SPECTROSCOPY, ComputingMethodologies_DOCUMENTANDTEXTPROCESSING, METHANOL, [SDU.ASTR.GA]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Galactic Astrophysics [astro-ph.GA], TRANSITION
Abstract

In the past decade, much progress has been made in characterising the processes leading to the enhanced deuterium fractionation observed in the ISM and in particular in the cold, dense parts of star forming regions such as protostellar envelopes. Very high molecular D/H ratios have been found for saturated molecules and ions. However, little is known about the deuterium fractionation in radicals, even though simple radicals often represent an intermediate stage in the formation of more complex, saturated molecules. The imidogen radical NH is such an intermediate species for the ammonia synthesis in the gas phase. Herschel/HIFI represents a unique opportunity to study the deuteration and formation mechanisms of such species, which are not observable from the ground. We searched here for the deuterated radical ND in order to determine the deuterium fractionation of imidogen and constrain the deuteration mechanism of this species. We observed the solar-mass Class 0 protostar IRAS16293-2422 with the heterodyne instrument HIFI as part of the Herschel key programme CHESS (Chemical HErschel Surveys of Star forming regions). The deuterated form of the imidogen radical ND was detected and securely identified with 2 hyperfine component groups of its fundamental transition in absorption against the continuum background emitted from the nascent protostar. The 3 groups of hyperfine components of its hydrogenated counterpart NH were also detected in absorption. We derive a very high deuterium fractionation with an [ND]/[NH] ratio of between 30 and 100%. The deuterium fractionation of imidogen is of the same order of magnitude as that in other molecules, which suggests that an efficient deuterium fractionation mechanism is at play. We discuss two possible formation pathways for ND, by means of either the reaction of N+ with HD, or deuteron/proton exchange with NH., Accepted; To appear in A&A Herschel/HIFI Special Issue

Published
2010
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40. The origin of the [C II] emission in the S140 photon-dominated regions. New insights from HIFI

Author

C. Dedes, M. Röllig, B. Mookerjea, Y. Okada, V. Ossenkopf, S. Bruderer, A. O. Benz, M. Melchior, C. Kramer, M. Gerin, R. Güsten, M. Akyilmaz, O. Berne, F. Boulanger, G. De Lange, L. Dubbeldam, K. France, A. Fuente, J. R. Goicoechea, A. Harris, R. Huisman, W. Jellema, C. Joblin, T. Klein, F. Le Petit, S. Lord, P. Martin, J. Martin-Pintado, D. A. Neufeld, S. Philipp, T. Phillips, P. Pilleri, J. R. Rizzo, M. Salez, R. Schieder, R. Simon, O. Siebertz, J. Stutzki, F. van der Tak, D. Teyssier, H. Yorke, Institute of Astronomy [ETH Zürich], Department of Physics [ETH Zürich] (D-PHYS), Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology in Zürich [Zürich] (ETH Zürich)-Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology in Zürich [Zürich] (ETH Zürich), Physikalisches Institut [Köln], Universität zu Köln, KOSMA, I. Physikalisches Institut, foreign laboratories (FL), CERN [Genève], Laboratoire Univers et Théories (LUTH (UMR_8102)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Max-Planck-Institut für Extraterrestrische Physik (MPE), Instituto de RadioAstronomía Milimétrica (IRAM), Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA (UMR_8112)), PSL Research University (PSL)-PSL Research University (PSL)-Université de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Division for Submm Technologies, Max-Planck-Institut für Radioastronomie (MPIFR), Centre d'étude spatiale des rayonnements (CESR), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-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), Center for Astrophysics and Space Astronomy [Boulder] (CASA), University of Colorado [Boulder], Observatorio Astronómico Nacional (OAN), oan, CRUK Medical Oncology Unit, The Churchill Hospital, Univ Toulouse UPS, Ctr Etud Spatiale Rayonnements, F-31062 Toulouse 9, France, Centre Etud Spatiale Rayonnements Toulouse, CITA, University of Toronto, Los Alamos National Laboratory (LANL), Helmholtz zentrum für Schwerionenforschung GmbH (GSI), European Space Astronomy Centre (ESAC), European Space Agency (ESA), Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS), Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich)- Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7), 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), 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)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées, and Astronomy

Subjects
Photon, ISM: structure, 010103 numerical & computational mathematics, Astrophysics, 01 natural sciences, CARBON, photon-dominated region (PDR), 0103 physical sciences, OUTFLOW, 0101 mathematics, Spectral resolution, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, ComputingMilieux_MISCELLANEOUS, Line (formation), Physics, STAR-FORMING REGIONS, ISM: kinematics and dynamics, MASS-SPECTRA, S140-IRS-1, photon, Astronomy and Astrophysics, submillimeter: general, Ionization front, FIELDS, Astrophysics - Astrophysics of Galaxies, ISM: molecules, CONTINUUM, 13. Climate action, Space and Planetary Science, dominated region (PDR), MOLECULAR CLOUDS, S 140, Outflow, S-140/L-1204, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

Using Herschel's HIFI instrument we have observed [C II] along a cut through S140 and high-J transitions of CO and HCO+ at two positions on the cut, corresponding to the externally irradiated ionization front and the embedded massive star forming core IRS1. The HIFI data were combined with available ground-based observations and modeled using the KOSMA-tau model for photon dominated regions. Here we derive the physical conditions in S140 and in particular the origin of [C II] emission around IRS1. We identify three distinct regions of [C II] emission from the cut, one close to the embedded source IRS1, one associated with the ionization front and one further into the cloud. The line emission can be understood in terms of a clumpy model of photon-dominated regions. At the position of IRS1, we identify at least two distinct components contributing to the [C II] emission, one of them a small, hot component, which can possibly be identified with the irradiated outflow walls. This is consistent with the fact that the [C II] peak at IRS1 coincides with shocked H2 emission at the edges of the outflow cavity. We note that previously available observations of IRS1 can be well reproduced by a single-component KOSMA-tau model. Thus it is HIFI's unprecedented spatial and spectral resolution, as well as its sensitivity which has allowed us to uncover an additional hot gas component in the S140 region.

Published
2010
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41. The methanol lines and hot core of OMC2-FIR4, an intermediate-mass protostar, with Herschel-HIFI

Author

M. Kama, C. Dominik, S. Maret, F. van der Tak, E. Caux, C. Ceccarelli, A. Fuente, N. Crimier, S. Lord, A. Bacmann, A. Baudry, T. Bell, M. Benedettini, E. A. Bergin, G. A. Blake, A. Boogert, S. Bottinelli, S. Cabrit, P. Caselli, A. Castets, J. Cernicharo, C. Codella, C. Comito, A. Coutens, K. Demyk, P. Encrenaz, E. Falgarone, M. Gerin, P. F. Goldsmith, F. Helmich, P. Hennebelle, T. Henning, E. Herbst, P. Hily-Blant, T. Jacq, C. Kahane, A. Klotz, W. Langer, B. Lefloch, D. Lis, A. Lorenzani, G. Melnick, B. Nisini, S. Pacheco, L. Pagani, B. Parise, J. Pearson, T. Phillips, M. Salez, P. Saraceno, P. Schilke, K. Schuster, X. Tielens, M. H. D. van der Wiel, C. Vastel, S. Viti, V. Wakelam, A. Walters, F. Wyrowski, H. Yorke, P. Cais, R. Güsten, S. Philipp, T. Klein, Laboratoire d'Astrophysique de Grenoble (LAOG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Astronomical Institute Anton Pannekoek (AI PANNEKOEK), University of Amsterdam [Amsterdam] (UvA), Centre d'étude spatiale des rayonnements (CESR), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-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), 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), Université Sciences et Technologies - Bordeaux 1, Laboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux (L3AB), Civilisations atlantiques & Archéosciences (C2A), Ministère de la Culture et de la Communication (MCC)-Centre National de la Recherche Scientifique (CNRS)-Université de Nantes - UFR Histoire, Histoire de l'Art et Archéologie (UFR HHAA), Université de Nantes (UN)-Université de Nantes (UN), Harvard-Smithsonian Center for Astrophysics (CfA), Harvard University [Cambridge]-Smithsonian Institution, Laboratoire Optimisation de la Conception et Ingénierie de l'Environnement (LOCIE), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-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 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-Seine-Université Paris-Seine-Centre National de la Recherche Scientifique (CNRS), INAF - Osservatorio Astrofisico di Arcetri (OAA), Istituto Nazionale di Astrofisica (INAF), Centro de Investigaciones Biológicas (CSIC), Consejo Superior de Investigaciones Científicas [Spain] (CSIC), Laboratoire de Cosmologie, Astrophysique Stellaire & Solaire, de Planétologie et de Mécanique des Fluides (CASSIOPEE), Université Nice Sophia Antipolis (... - 2019) (UNS), Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Radioastronomie (LRA), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Max-Planck-Institut für Astronomie (MPIA), Max-Planck-Gesellschaft, Ohio State University [Columbus] (OSU), Observatoire de Haute-Provence (OHP), Institut Pythéas (OSU PYTHEAS), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Centre National de la Recherche Scientifique (CNRS), Osservatorio di Astrofisica di Roma (OAR), Istituto di Fisica dello Spazio Interplanetario (IFSI), Consiglio Nazionale delle Ricerche (CNR), Max-Planck-Institut für Radioastronomie (MPIFR), SRON Netherlands Institute for Space Research (SRON), 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 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), Harvard University-Smithsonian Institution, 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), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), INAF - Osservatorio Astronomico di Roma (OAR), National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), 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)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées, Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Ministère de la Culture et de la Communication (MCC)-Université de Rennes 2 (UR2), Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS)-Université de Nantes - UFR Histoire, Histoire de l'Art et Archéologie (UFR HHAA), École normale supérieure - Paris (ENS Paris), Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Institut de Recherche pour le Développement (IRD), Astronomy, Low Energy Astrophysics (API, FNWI), Université de Nantes - UFR Histoire, Histoire de l'Art et Archéologie (UFR HHAA), Université de Nantes (UN)-Université de Nantes (UN)-Centre National de la Recherche Scientifique (CNRS)-Ministère de la Culture et de la Communication (MCC), and Smithsonian Institution-Harvard University [Cambridge]

Subjects
010504 meteorology & atmospheric sciences, Astronomy, Population, FOS: Physical sciences, Astrophysics, 01 natural sciences, ISM: abundances, EXPLANATION, chemistry.chemical_compound, MOLECULES, INTERSTELLAR CLOUDS, 0103 physical sciences, Protostar, education, 010303 astronomy & astrophysics, DIAGNOSTIC-TOOL, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Line (formation), Envelope (waves), QB, Physics, ISM: kinematics and dynamics, STAR-FORMING REGIONS, Range (particle radiation), education.field_of_study, stars: formation, PACS SPECTROSCOPY, Research Programm of Institute for Mathematics, Astrophysics and Particle Physics, Star formation, [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Astronomy and Astrophysics, [PHYS.ASTR.SR]Physics [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Astrophysics - Astrophysics of Galaxies, ISM: molecules, Core (optical fiber), ENVELOPES, chemistry, Space and Planetary Science, GAS, Astrophysics of Galaxies (astro-ph.GA), ComputingMethodologies_DOCUMENTANDTEXTPROCESSING, ABUNDANCE, Methanol, EMISSION, Galaxy Astrophysics
Abstract

In contrast with numerous studies on the physical and chemical structure of low- and high-mass protostars, much less is known about their intermediate-mass counterparts, a class of objects that could help to elucidate the mechanisms of star formation on both ends of the mass range. We present the first results from a rich HIFI spectral dataset on an intermediate-mass protostar, OMC2-FIR4, obtained in the CHESS (Chemical HErschel SurveyS of star forming regions) key programme. The more than 100 methanol lines detected between 554 and 961 GHz cover a range in upper level energy of 40 to 540 K. Our physical interpretation focusses on the hot core, but likely the cold envelope and shocked regions also play a role in reality, because an analysis of the line profiles suggests the presence of multiple emission components. An upper limit of 10^-6 is placed on the methanol abundance in the hot core, using a population diagram, large-scale source model and other considerations. This value is consistent with abundances previously seen in low-mass hot cores. Furthermore, the highest energy lines at the highest frequencies display asymmetric profiles, which may arise from infall around the hot core., Comment: 2 figures, accepted for publication in the A&A Herschel-HIFI special issue

Published
2010
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42. Evolution of massive protostars: the IRAS 18151-1208 region

Author

F. F. S. van der Tak, Cormac Purcell, Sylvain Bontemps, Fabrice Herpin, M. Marseille, Astronomy, MRPS Maison Régionale de Promotion de la Santé Nord Pas de Calais, 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), 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), Observatoire aquitain des sciences de l'univers (OASU), Laboratoire Hétérochimie Fondamentale et Appliquée (LHFA), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Institut de Chimie de Toulouse (ICT-FR 2599), Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD), Max-Planck-Institut für Radioastronomie (MPIFR), SRON Netherlands Institute for Space Research (SRON), Swinburne University of Technology (Hawthorn campus), Jodrell Bank Observatory, University of Manchester [Manchester], Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut de Chimie de Toulouse (ICT), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), and Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)

Subjects
010504 meteorology & atmospheric sciences, PROTOSTELLAR CANDIDATES, Continuum (design consultancy), LINE, FOS: Physical sciences, Astrophysics, HOT-CORE, 01 natural sciences, [PHYS.ASTR.CO]Physics [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO], ISM : individual objects : IRAS 18151-1208, RADIATIVE-TRANSFER, Abundance (ecology), Phase (matter), 0103 physical sciences, Protostar, 010303 astronomy & astrophysics, MILLIMETER, 0105 earth and related environmental sciences, Physics, STAR-FORMING REGIONS, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], stars : formation, Astrophysics (astro-ph), MONTE-CARLO METHOD, Astronomy and Astrophysics, ISM : abundances, YOUNG STELLAR OBJECTS, Stars, CONTINUUM, 13. Climate action, Space and Planetary Science, line : profiles, Outflow, Early phase, MOLECULAR OUTFLOWS
Abstract

The study of physical and chemical properties of massive protostars is critical to better understand the evolutionary sequence which leads to the formation of high-mass stars. IRAS 18151-1208 is a nearby massive region (d = 3kpc, L ~ 20000 Lsun) which splits into three cores: MM1, MM2 and MM3 (separated by 1'-2'). We aim at (1) studying the physical and chemical properties of the individual MM1, MM2 and MM3 cores; (2) deriving their evolutionary stages; (3) using these results to improve our view of the evolutionary sequence of massive cores. The region was observed in the CS, C34S, H2CO, HCO+, H13CO+, and N2H+ lines at mm wavelengths with the IRAM 30m and Mopra telescopes. We use 1D and 2D modeling of the dust continuum to derive the density and temperature distributions, which are then used in the RATRAN code to model the lines and constrain the abundances of the observed species. All the lines were detected in MM1 and MM2. MM3 shows weaker emission, or even is undetected in HCO+ and all isotopic species. MM2 is driving a newly discovered CO outflow and hosts a mid-IR-quiet massive protostar. The abundance of CS is significantly larger in MM1 than in MM2, but smaller than in a reference massive protostar such as AFGL2591. In contrast the N2H+ abundance decreases from MM2 to MM1, and is larger than in AFGL2591. Both MM1 and MM2 host an early phase massive protostar, but MM2 (and mid-IR-quiet sources in general) is younger and more dominated by the host protostar than MM1 (mid-IR-bright). The MM3 core is probably in a pre-stellar phase. We find that the N2H+/C34S ratio varies systematically with age in the massive protostars for which the data are available. It can be used to identify young massive protostars., Comment: 19 pages, 17 figures, accepted by A&A the 3 June 2008

Published
2008
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43. HDO abundance in the envelope of the solar-type protostar IRAS16293-2422

Author

Alain Castets, Claudine Kahane, Stéphanie Cazaux, C. Comito, Laurent Loinard, Valentine Wakelam, Peter Schilke, E. F. van Dishoeck, Berengere Parise, Emmanuel Caux, A. G. G. M. Tielens, Adam Walters, Frank Helmich, Aurore Bacmann, Cecilia Ceccarelli, Laboratoire d'Astrophysique de Grenoble (LAOG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Kapteyn Astronomical Institute, Astronomy, Centre d'étude spatiale des rayonnements (CESR), 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)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées, 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), 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), Observatoire aquitain des sciences de l'univers (OASU), Centro de Radioastronomia y Astrofisica (CRyA), Universidad Nacional Autónoma de México (UNAM), SRON Netherlands Institute for Space Research (SRON), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Laboratoire de Cosmologie, Astrophysique Stellaire & Solaire, de Planétologie et de Mécanique des Fluides (CASSIOPEE), Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Max-Planck-Institut für Radioastronomie (MPIFR), Leiden Observatory [Leiden], Universiteit Leiden [Leiden], Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-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), 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 Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Universidad Nacional Autónoma de México = National Autonomous University of Mexico (UNAM), Université Nice Sophia Antipolis (1965 - 2019) (UNS), and Universiteit Leiden

Subjects
010504 meteorology & atmospheric sciences, [PHYS.ASTR.EP]Physics [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Evaporation, [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], FOS: Physical sciences, CHEMICAL EVOLUTION, Astrophysics, 01 natural sciences, [PHYS.ASTR.CO]Physics [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO], IRAS 16293-2422, ISM : molecules, SURFACE-CHEMISTRY, PRESTELLAR CORES, Abundance (ecology), DOUBLY DEUTERATED FORMALDEHYDE, Phase (matter), 0103 physical sciences, Protostar, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, Envelope (waves), QB, Physics, STAR-FORMING REGIONS, stars: formation, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], LOW-MASS PROTOSTARS, INTERSTELLAR-MEDIUM, stars : formation, Astrophysics (astro-ph), stars : individual : IRAS 16293-2422, Astronomy and Astrophysics, ISM: molecules, stars: individual: IRAS 16293-2422, HOT CORE, Bright spot, 13. Climate action, Space and Planetary Science, Outflow, Order of magnitude, HIGH-RESOLUTION
Abstract

We present IRAM 30m and JCMT observations of HDO lines towards the solar-type protostar IRAS 16293-2422. Five HDO transitions have been detected on-source, and two were unfruitfully searched for towards a bright spot of the outflow of IRAS 16293-2422. We interpret the data by means of the Ceccarelli, Hollenbach and Tielens (1996) model, and derive the HDO abundance in the warm inner and cold outer parts of the envelope. The emission is well explained by a jump model, with an inner abundance of 1e-7 and an outer abundance lower than 1e-9 (3 sigma). This result is in favor of HDO enhancement due to ice evaporation from the grains in theinner envelope. The deuteration ratio HDO/H2O is found to be f_in=3% and f_out < 0.2% (3 sigma) in the inner and outer envelope respectively and therefore, the fractionation also undergoes a jump in the inner part of the envelope. These results are consistent with the formation of water in the gas phase during the cold prestellar core phase and storage of the molecules on the grains, but do not explain why observations of H2O ices consistently derive a H2O ice abundance of several 1e-5 to 1e-4, some two orders of magnitude larger than the gas phase abundance of water in the hot core around IRAS 16293-2422., 9 pages, 6 figures accepted by A&A

Published
2004
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44. Evolution of CO lines in time-dependent models of protostellar disk formation

Author

Ruud Visser, Daniel Harsono, Ewine F. van Dishoeck, Lars E. Kristensen, and Simon Bruderer

Subjects
010504 meteorology & atmospheric sciences, Stellar mass, FOS: Physical sciences, SPECTRAL ENERGY-DISTRIBUTIONS, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Excitation temperature, 01 natural sciences, Spectral line, methods: numerical, Luminosity, accretion, SUBMILLIMETER ARRAY, HL TAURI, Planet, CIRCUMSTELLAR DISKS, 0103 physical sciences, Radiative transfer, Astrophysics::Solar and Stellar Astrophysics, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences, Line (formation), STAR-FORMING REGIONS, Physics, accretion, accretion disks, stars: formation, LOW-MASS PROTOSTARS, astrochemistry, Star formation, accretion disks, Astronomy and Astrophysics, MAGNETIC BRAKING CATASTROPHE, YOUNG STELLAR OBJECTS, Astrophysics - Astrophysics of Galaxies, PROTOPLANETARY DISK, Astrophysics - Solar and Stellar Astrophysics, radiative transfer, 13. Climate action, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), MOLECULAR-LINE, Astrophysics::Earth and Planetary Astrophysics
Abstract

(Abridged) Star and planet formation theories predict an evolution in the density, temperature, and velocity structure as the envelope collapses and forms an accretion disk. The aim of this work is to model the evolution of the molecular excitation, line profiles, and related observables during low-mass star formation. Specifically, the signatures of disks during the deeply embedded stage are investigated. Semi-analytic 2D axisymmetric models have been used to describe the evolution of the density, stellar mass, and luminosity from the pre-stellar to the T-Tauri phase. A full radiative transfer calculation is carried out to accurately determine the time-dependent dust temperatures and CO abundance structure. We present non-LTE near-IR, FIR, and submm lines of CO have been simulated at a number of time steps. In contrast to the dust temperature, the CO excitation temperature derived from submm/FIR lines does not vary during the protostellar evolution, consistent with C18O observations obtained with Herschel and from ground-based telescopes. The near-IR spectra provide complementary information to the submm lines by probing not only the cold outer envelope but also the warm inner region. The near-IR high-J (>8) absorption lines are particularly sensitive to the physical structure of the inner few AU, which does show evolution. High signal-to-noise ratio subarcsec resolution data with ALMA are needed to detect the presence of small rotationally supported disks during the Stage 0 phase and various diagnostics are discussed., Accepted for publication in A&A, 17 pages with appendix; 14 figures

Published
2013
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45. FIRST DETECTION OF WATER VAPOR IN A PRE-STELLAR CORE

Author

Laurent Pagani, Edwin A. Bergin, Mario Tafalla, Paola Caselli, Thomas Douglas, Eric Keto, Umut A. Yildiz, Yuri Aikawa, Lars E. Kristensen, Floris van der Tak, Brunella Nisini, Ewine F. van Dishoeck, Claudio Codella, C. Malcolm Walmsley, INAF - Osservatorio Astrofisico di Arcetri (OAA), Istituto Nazionale di Astrofisica (INAF), Harvard-Smithsonian Center for Astrophysics (CfA), Harvard University-Smithsonian Institution, Department of Earth and Planetary Sciences [Kobe], Kobe University, 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), SRON Netherlands Institute for Space Research (SRON), Leiden Observatory [Leiden], Universiteit Leiden, Astronomy, Harvard University [Cambridge]-Smithsonian Institution, École normale supérieure - Paris (ENS Paris), and Universiteit Leiden [Leiden]

Subjects
ROTATIONAL-EXCITATION, 010504 meteorology & atmospheric sciences, Interstellar cloud, FOS: Physical sciences, Cosmic ray, Astrophysics, ISM: clouds, 01 natural sciences, GAS TEMPERATURE, MOLECULES, RADIATIVE-TRANSFER, 0103 physical sciences, Radiative transfer, Astrophysics::Solar and Stellar Astrophysics, ACCRETION, 010303 astronomy & astrophysics, ComputingMilieux_MISCELLANEOUS, Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences, Line (formation), STAR-FORMING REGIONS, [PHYS]Physics [physics], Physics, stars: formation, DENSE INTERSTELLAR CLOUDS, astrochemistry, Star formation, line: profiles, Astronomy and Astrophysics, Planetary system, Astrophysics - Astrophysics of Galaxies, ISM: molecules, Pre-stellar core, 13. Climate action, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), Astrophysics::Earth and Planetary Astrophysics, DEPLETION, EMISSION, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], PRESTELLAR CORE, Water vapor
Abstract

Water is a crucial molecule in molecular astrophysics as it controls much of the gas/grain chemistry, including the formation and evolution of more complex organic molecules in ices. Pre-stellar cores provide the original reservoir of material from which future planetary systems are built, but few observational constraints exist on the formation of water and its partitioning between gas and ice in the densest cores. Thanks to the high sensitivity of the Herschel Space Observatory, we report on the first detection of water vapor at high spectral resolution toward a dense cloud on the verge of star formation, the pre-stellar core L1544. The line shows an inverse P-Cygni profile, characteristic of gravitational contraction. To reproduce the observations, water vapor has to be present in the cold and dense central few thousand AU of L1544, where species heavier than Helium are expected to freeze-out onto dust grains, and the ortho:para H2 ratio has to be around 1:1 or larger. The observed amount of water vapor within the core (about 1.5x10^{-6} Msun) can be maintained by Far-UV photons locally produced by the impact of galactic cosmic rays with H2 molecules. Such FUV photons irradiate the icy mantles, liberating water wapor in the core center. Our Herschel data, combined with radiative transfer and chemical/dynamical models, shed light on the interplay between gas and solids in dense interstellar clouds and provide the first measurement of the water vapor abundance profile across the parent cloud of a future solar-type star and its potential planetary system., Comment: The Astrophysical Journal Letters, in press

Published
2012
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46. The JCMT Spectral Legacy Survey: physical structure of the molecular envelope of the high-mass protostar AFGL2591

Author

J. L. Williams, F. F. S. van der Tak, Marco Spaans, Gary A. Fuller, R. Plume, H. Roberts, M. H. D. van der Wiel, and Astronomy

Subjects
ROTATIONAL-EXCITATION, medicine.medical_specialty, FOS: Physical sciences, CYGNUS-X, Astrophysics, DENSE CORES, CHEMISTRY, medicine, Radiative transfer, Astrophysics::Solar and Stellar Astrophysics, Protostar, OUTFLOW, Astrophysics::Galaxy Astrophysics, Optical depth, Line (formation), Envelope (waves), STAR-FORMING REGIONS, Physics, stars: formation, ISM: individual objects: AFGL2591, MONTE-CARLO METHOD, Astronomy and Astrophysics, YOUNG STELLAR OBJECTS, Astrophysics - Astrophysics of Galaxies, LINE OBSERVATIONS, ISM: molecules, Spectral imaging, Stars, techniques: imaging spectroscopy, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), CLOUD CORES, Substructure
Abstract

The understanding of the formation process of massive stars (>8 Msun) is limited, due to theoretical complications and observational challenges. We investigate the physical structure of the large-scale (~10^4-10^5 AU) molecular envelope of the high-mass protostar AFGL2591 using spectral imaging in the 330-373 GHz regime from the JCMT Spectral Legacy Survey. Out of ~160 spectral features, this paper uses the 35 that are spatially resolved. The observed spatial distributions of a selection of six species are compared with radiative transfer models based on a static spherically symmetric structure, a dynamic spherical structure, and a static flattened structure. The maps of CO and its isotopic variations exhibit elongated geometries on scales of ~100", and smaller scale substructure is found in maps of N2H+, o-H2CO, CS, SO2, CCH, and methanol lines. A velocity gradient is apparent in maps of all molecular lines presented here, except SO, SO2, and H2CO. We find two emission peaks in warm (Eup~200K) methanol separated by 12", indicative of a secondary heating source in the envelope. The spherical models are able to explain the distribution of emission for the optically thin H13CO+ and C34S, but not for the optically thick HCN, HCO+, and CS, nor for the optically thin C17O. The introduction of velocity structure mitigates the optical depth effects, but does not fully explain the observations, especially in the spectral dimension. A static flattened envelope viewed at a small inclination angle does slightly better. We conclude that a geometry of the envelope other than an isotropic static sphere is needed to circumvent line optical depth effects. We propose that this could be achieved in envelope models with an outflow cavity and/or inhomogeneous structure at scales smaller than ~10^4 AU. The picture of inhomogeneity is supported by observed substructure in at least six species., 17 pages; accepted for publication in A&A

Published
2011
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47. Astrochemical Properties of Planck Cold Clumps

Author

Jungha Kim, Yuefang Wu, Sheng-Yuan Liu, Naomi Hirano, Takeshi Sakai, L. Viktor Tóth, Ke Wang, Tomoya Hirota, Tie Liu, Ken'ichi Tatematsu, Mika Juvela, Hiroko Shinnaga, Gary A. Fuller, Isabelle Ristorcelli, Miju Kang, Kee-Tae Kim, Maria Cunningham, Di Li, Satoshi Ohashi, Mark Thompson, Jeong-Eun Lee, Jinhua He, Minho Choi, Quang Nguyen Luong, Patricio Sanhueza, James Di Francesco, Masao Saito, and Department of Physics

Subjects
Angular momentum, CHEMICAL VARIATION, 010504 meteorology & atmospheric sciences, ISM: structure, FOS: Physical sciences, Astrophysics, 7. Clean energy, 01 natural sciences, ISM: clouds, DENSE CORES, symbols.namesake, 0103 physical sciences, 45-M RADIO TELESCOPE, PHYSICAL CONDITIONS, Planck, 010303 astronomy & astrophysics, molecules [ISM], 0105 earth and related environmental sciences, Physics, STAR-FORMING REGIONS, formation [stars], stars: formation, Series (mathematics), Astronomy and Astrophysics, 115 Astronomy, Space science, Astrophysics - Astrophysics of Galaxies, ISM: molecules, DEUTERIUM FRACTIONATION, 13. Climate action, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), MOLECULAR CLOUD CORES, symbols, Compositional variation, structure [ISM], ANGULAR-MOMENTUM, clouds [ISM], INFRARED DARK CLOUDS, MAPPING OBSERVATIONS
Abstract

We observed thirteen Planck cold clumps with the James Clerk Maxwell Telescope/SCUBA-2 and with the Nobeyama 45 m radio telescope. The N$_2$H$^+$ distribution obtained with the Nobeyama telescope is quite similar to SCUBA-2 dust distribution. The 82 GHz HC$_3$N, 82 GHz CCS, and 94 GHz CCS emission are often distributed differently with respect to the N$_2$H$^+$ emission. The CCS emission, which is known to be abundant in starless molecular cloud cores, is often very clumpy in the observed targets. We made deep single-pointing observations in DNC, HN$^{13}$C, N$_2$D$^+$, cyclic-C$_3$H$_2$ toward nine clumps. The detection rate of N$_2$D$^+$ is 50\%. Furthermore, we observed the NH$_3$ emission toward 15 Planck cold clumps to estimate the kinetic temperature, and confirmed that most of targets are cold ($\lesssim$ 20 K). In two of the starless clumps observe, the CCS emission is distributed as it surrounds the N$_2$H$^+$ core (chemically evolved gas), which resembles the case of L1544, a prestellar core showing collapse. In addition, we detected both DNC and N$_2$D$^+$. These two clumps are most likely on the verge of star formation. We introduce the Chemical Evolution Factor (CEF) for starless cores to describe the chemical evolutionary stage, and analyze the observed Planck cold clumps., 20 figures, 13 tables, ApJS, in press

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