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1. Cloud-scale radio surveys of star formation and feedback in Triangulum Galaxy M 33: VLA observations.

Author

Tabatabaei, F S, Cotton, W, Schinnerer, E, Beck, R, Brunthaler, A, Menten, K M, Braine, J, Corbelli, E, Kramer, C, Beckman, J E, Knapen, J H, Paladino, R, Koch, E, and Camps Fariña, A

Subjects
*MAGNETIC flux density, *INTERSTELLAR medium, *COSMIC rays, *SUPERGIANT stars, *GALACTIC evolution, *STAR formation
Abstract

Studying the interplay between massive star formation and the interstellar medium (ISM) is paramount to understand the evolution of galaxies. Radio continuum (RC) emission serves as an extinction-free tracer of both massive star formation and the energetic components of the ISM. We present a multiband RC survey of the Local Group galaxy M 33 down to ≃30 pc linear resolution observed with the Karl G. Jansky Very Large Array (VLA). We calibrate the star formation rate surface density and investigate the impact of diffuse emission on this calibration using a structural decomposition. Separating the thermal and non-thermal emission components, the correlation between different phases of the ISM, and the impact of massive star formation are being investigated. Radio sources with sizes ≲200 pc constitute about 36 per cent (46 per cent) of the total RC emission at 1.5 GHz (6.3 GHz) in the inner 18 × 18 arcmin2 (or 4 kpc × 4 kpc) disc of M 33. The non-thermal spectral index becomes flatter with increasing star formation rate surface density, indicating the escape of cosmic ray electrons from their birth places. The magnetic field strength also increases with star formation rate following a bi-modal relation, indicating that the small-scale turbulent dynamo acts more efficiently at higher luminosities and star formation rates. Although the correlations are tighter in star-forming regions, the non-thermal emission is also correlated with the more quiescent molecular gas in the ISM. An almost linear molecular star formation law exists in M 33 when excluding diffuse structures. Massive star formation amplifies the magnetic field and increases the number of high-energy cosmic ray electrons, which can help the onset of winds and outflows. [ABSTRACT FROM AUTHOR]

Published
2022
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2. Probability distribution functions of gas surface density in M 33.

Author

Corbelli, Edvige, Elmegreen, Bruce G., Braine, Jonathan, and Thilker, David

Subjects
*INTERSTELLAR medium, *GRAVITATION, *TURBULENCE, *MACH number, *DISTRIBUTION (Probability theory)
Abstract

Aims. We examine the interstellar medium (ISM) of M 33 to unveil fingerprints of self-gravitating gas clouds throughout the star-forming disk. Methods. The probability distribution functions (PDFs) for atomic, molecular, and total gas surface densities are determined at a resolution of about 50 pc over regions that share coherent morphological properties and considering cloud samples at different evolutionary stages in the star formation cycle. Results. Most of the total gas PDFs are well fit by log-normal functions whose width decreases radially outward. Because the HI velocity dispersion is approximately constant throughout the disk, the decrease in PDF width is consistent with a lower Mach number for the turbulent ISM at large galactocentric radii where a higher fraction of HI is in the warm phase. The atomic gas is found mostly at face-on column densities below NHlim = 2.5 × 1021 cm−2 N H lim = 2.5 × 10 21   c m − 2 $N_{\rm{H}}^{{\lim}} = 2.5 \times {10^{21}} \ {\rm{c}}{{\rm{m}}^{- 2}}$ , with small radial variations of NHlim N H lim $N_{\rm{H}}^{{\lim}}$. The molecular gas PDFs do not show strong deviations from log-normal functions in the central region where molecular fractions are high. Here the high pressure and rate of star formation shapes the PDF as a log-normal function, dispersing self-gravitating complexes with intense feedback at all column densities that are spatially resolved. Power-law PDFs for the molecules are found near and above NHlim N H lim $N_{\rm{H}}^{{\lim}}$ , in the southern spiral arm and in a continuous dense filament extending at larger galactocentric radii. In the filament nearly half of the molecular gas departs from a log-normal PDF, and power laws are also observed in pre-star-forming molecular complexes. The slope of the power law is between −1 and −2. This slope, combined with maps showing where the different parts of the power law PDFs come from, suggests a power-law stratification of the density within molecular cloud complexes, in agreement with the dominance of self-gravity. [ABSTRACT FROM AUTHOR]

Published
2018
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3. Wind and nebula of the M 33 variable GR 290 (WR/LBV).

Author

Maryeva, Olga, Koenigsberger, Gloria, Egorov, Oleg, Rossi, Corinne, Polcaro, Vito Francesco, Calabresi, Massimo, and Viotti, Roberto F.

Subjects
*NEBULAE, *VARIABLE stars, *SUPERGIANT stars, *ATMOSPHERIC structure, *STELLAR luminosity function
Abstract

Context. GR 290 (M 33/V532 = Romano's Star) is a suspected post-luminous blue variable star located in M 33 galaxy that shows a rare Wolf–Rayet (WR) spectrum during its minimum light phase. In spite of many studies, its atmospheric structure, its circumstellar environment, and its place in the general context of massive stars' evolution is poorly known. Aims. We present a detailed study of this star's wind and mass loss, and a study of the circumstellar environment associated to the star. Methods. Long-slit spectra of GR 290 were obtained during its present minimum luminosity phase with the Gran Telescopio Canarias covering the ∼3600–7500 Å wavelength range together with contemporaneous photometry using B, V, R and I filters. The data were compared with non-local thermodynamical equilibrium (non-LTE) model atmosphere synthetic spectra computed with CMFGEN code and with models for ionized interstellar medium regions computed with CLOUDY code. Results. The current mV = 18.8 mag is the faintest at which this source has ever been observed. The non-LTE models indicate effective temperatures of Teff = 27 000–30 000 K at radius R2/3 = 27−21 R⊙ and mass-loss rate Ṁ = 1.5 × 10−5M⊙yr−1. The terminal wind speed v∞ = 620 km s−1 is faster than ever before recorded, while the current luminosity L* = (3.1–3.7) × 105L⊙ is the lowest ever deduced. The star is overabundant in He and N and underabundant in C and O. It is surrounded by an unresolved compact H II region with dimensions ≤4 pc, from where H-Balmer, He I lines, and [O III] and [N II] are detected. In addition, we find emission from a more extended interstellar medium (ISM) region, which appears to be asymmetric, with a larger extent to the east (16–40 pc) than to the west. Conclusions. In the present long lasting visual minimum, GR 290 is in a lower bolometric luminosity state with higher mass-loss rate. The nearby nebular emission seems to suggest that the star has undergone significant mass loss over the past 104–105 yr and is nearing the end stages of its evolution. [ABSTRACT FROM AUTHOR]

Published
2018
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4. AGB population as probes of galaxy structure and evolution.

Author

Javadi, Atefeh and van Loon, Jacco Th.

Abstract

The evolution of galaxies is driven by the birth and death of stars. AGB stars are at the end points of their evolution and therefore their luminosities directly reflect their birth mass; this enables us to reconstruct the star formation history. These cool stars also produce dust grains that play an important role in the temperature regulation of the interstellar medium (ISM), chemistry, and the formation of planets. These stars can be resolved in all of the nearby galaxies. Therefore, the Local Group of galaxies offers us a superb near-field cosmology site. Here we can reconstruct the formation histories, and probe the structure and dynamics, of spiral galaxies, of the many dwarf satellite galaxies surrounding the Milky Way and Andromeda, and of isolated dwarf galaxies. It also offers a variety of environments in which to study the detailed processes of galaxy evolution through studying the mass-loss mechanism and dust production by cool evolved stars. In this paper, I will first review our recent efforts to identify mass-losing Asymptotic Giant Branch (AGB) stars and red supergiants (RSGs) in Local Group galaxies and to correlate spatial distributions of the AGB stars of different mass with galactic structures. Then, I will outline our methodology to reconstruct the star formation histories using variable pulsating AGB stars and RSGs and present the results for rates of mass–loss and dust production by pulsating AGB stars and their analysis in terms of stellar evolution and galaxy evolution. [ABSTRACT FROM AUTHOR]

Published
2018
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5. Spatially resolving the dust properties and submillimetre excess in M 33.

Author

Relaño, M., De Looze, I., Kennicutt, R. C., Lisenfeld, U., Dariush, A., Verley, S., Braine, J., Tabatabaei, F., Kramer, C., Boquien, M., Xilouris, M., and Gratier, P.

Subjects
*SUBMILLIMETER astronomy, *GALACTIC evolution, *EMISSIVITY, *STELLAR mass, *MOLECULAR gas lasers
Abstract

Context. The relative abundance of the dust grain types in the interstellar medium is directly linked to physical quantities that trace the evolution of galaxies. Because of the poor spatial resolution of the infrared and submillimetre data, we are able to study the dependence of the resolved infrared spectral energy distribution (SED) across regions of the interstellar medium (ISM) with different physical properties in just a few objects. Aims. We aim to study the dust properties of the whole disc of M 33 at spatial scales of ~170 pc. This analysis allows us to infer how the relative dust grain abundance changes with the conditions of the ISM, study the existence of a submillimetre excess and look for trends of the gas-to-dust mass ratio (GDR) with other physical properties of the galaxy. Methods. For each pixel in the disc of M 33 we have fitted the infrared SED using a physically motivated dust model that assumes an emissivity index β close to two. We applied a Bayesian statistical method to fit the individual SEDs and derived the best output values from the study of the probability density function of each parameter. We derived the relative amount of the different dust grains in the model, the total dust mass, and the strength of the interstellar radiation field (ISRF) heating the dust at each spatial location. Results. The relative abundance of very small grains tends to increase, and for big grains to decrease, at high values of Hα luminosity. This shows that the dust grains are modified inside the star-forming regions, in agreement with a theoretical framework of dust evolution under different physical conditions. The radial dependence of the GDR is consistent with the shallow metallicity gradient observed in this galaxy. The strength of the ISRF derived in our model correlates with the star formation rate in the galaxy in a pixel by pixel basis. Although this is expected, it is the first time that a correlation between the two quantities has been reported. We have produced a map of submillimetre excess in the 500 μm SPIRE band for the disc of M 33. The excess can be as high as 50% and increases at large galactocentric distances. We further studied the relation of the excess with other physical properties of the galaxy and find that the excess is prominent in zones of diffuse ISM outside the main star-forming regions, where the molecular gas and dust surface density are low. [ABSTRACT FROM AUTHOR]

Published
2018
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6. Detailed abundance analysis of globular clusters in the Local Group: NGC 147, NGC 6822, and Messier 33.

Author

Larsen, S. S., Brodie, J. P., Wasserman, A., and Strader, J.

Subjects
*GLOBULAR clusters, *STELLAR populations, *EXTRAGALACTIC distances, *TRIANGULUM Galaxy, LOCAL Group (Astronomy)
Abstract

Context. Globular clusters (GCs) are emerging as powerful tracers of the chemical composition of extragalactic stellar populations. Aims. We present new abundance measurements for 11 GCs in the Local Group galaxies NGC 147, NGC 6822, and Messier 33. These are combined with previously published observations of four GCs in the Fornax and Wolf-Lundmark-Melotte (WLM) galaxies. Methods. The abundances were determined from analyses of integrated-light spectra obtained with the HIRES spectrograph on the Keck I telescope and with UVES on the Very Large Telescope (VLT). We used our analysis technique that was developed for this purpose and tested on Milky Way GCs. Results. We find that the clusters with [Fe/H] < -1.5 are all α-enhanced at about the same level as Milky Way GCs. Their Na abundances are also generally enhanced relative to Milky Way halo stars, suggesting that these extragalactic GCs resemble their Milky Way counterparts in containing large numbers of Na-rich stars. For [Fe/H] > -1.5, the GCs in M33 are also α-enhanced, while the GCs that belong to dwarfs (NGC 6822 SC7 and Fornax 4) have closer to solar-scaled α-element abundances. The abundance patterns in SC7 are remarkably similar to those in the Galactic GC Ruprecht 106, including significantly subsolar [Na/Fe] and [Ni/Fe] ratios. In NGC 147, the GCs with [Fe/H] < -2.0 account for about 6% of the total luminosity of stars in the same metallicity range, a lower fraction than those previously found in the Fornax and WLM galaxies, but substantially higher than in the Milky Way halo. Conclusions. At low metallicities, the abundance patterns suggest that GCs in the Milky Way, dwarf galaxies, and M33 experienced similar enrichment histories and/or processes. At higher metallicities, the lower levels of α-enhancement in the GCs found in dwarf galaxies resemble the abundance patterns observed in field stars in nearby dwarfs. Constraining the presence of multiple populations in these GCs is complicated by lack of information about detailed abundances in field stars of the corresponding metallicities. We suggest that correlations such as [Na/Fe] versus [Ni/Fe] may prove useful for this purpose if an accuracy of ~ 0.1 dex or better can be reached for integrated-light measurements. [ABSTRACT FROM AUTHOR]

Published
2018
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7. A deep narrowband survey for planetary nebulae at the outskirts of M 33.

Author

Galera-Rosillo, R., Corradi, R. L. M., and Mampaso, A.

Abstract

Context. Planetary nebulae (PNe) are excellent tracers of stellar populations with low surface brightness, and therefore provide a pow- erful method to detect and explore the rich system of substructures discovered around the main spiral galaxies of the local group. Aims. We searched the outskirts of the local group spiral galaxy M 33 (the Triangulum) for PNe to gain new insights into the extended stellar substructure on the northern side of the disc and to study the existence of a faint classical halo. Methods. The search is based on wide field imaging covering a 4.5 square degree area out to a maximum projected distance of about 40 kpc from the centre of the galaxy. The PN candidates are detected by the combination of images obtained in narrowband filters selecting the [OIII]λ5007 Å and Hα + [NII] nebular lines and in the continuum g1 and r1 broadband filters. Results. Inside the bright optical disc of M33, eight new PN candidates were identified, three of which were spectroscopically con- firmed. No PN candidates were found outside the limits of the disc. Fourteen additional sources showing [OIII] excess were also discovered. Conclusions. The absence of bright PN candidates in the area outside the galaxy disc covered by this survey sets an upper limit to the luminosity of the underlying population of ~1.6 × 107 L๏, suggesting the lack of a massive classical halo, which is in agreement with the results obtained using the red giant branch population. [ABSTRACT FROM AUTHOR]

Published
2018
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8. The molecular gas mass of M 33.

Author

Gratier, P., Braine, J., Schuster, K., Rosolowsky, E., Boquien, M., Calzetti, D., Combes, F., Kramer, C., Henkel, C., Herpin, F., Israel, F., Koribalski, B. S., Mookerjea, B., Tabatabaei, F. S., Röllig, M., van der Tak, F. F. S., van der Werf, P., and Wiedner, M.

Subjects
*CONSTITUTION of stars, *GAS dynamics, *ASTROCHEMISTRY, *INTERSTELLAR molecules
Abstract

Do some environments favor efficient conversion of molecular gas into stars? To answer this, we need to be able to estimate the H2 mass. Traditionally, this is done using CO observations and a few assumptions but the Herschel observations which cover the far-IR dust spectrum make it possible to estimate the molecular gas mass independently of CO and thus to investigate whether and how the CO traces H2. Previous attempts to derive gas masses from dust emission suffered from biases. Generally, dust surface densities, Hi column densities, and CO intensities are used to derive a gas-to-dust ratio (GDR) and the local CO intensity to H2 column density ratio (XCO), sometimes allowing for an additional CO-dark gas component (Kdark). We tested earlier methods, revealing degeneracies among the parameters, and then used a sophisticated Bayesian formalism to derive the most likely values for each of the parameters mentioned above as a function of position in the nearby prototypical low metallicity (12 + log(O=H) ! 8.4) spiral galaxy M 33. The data are from the IRAM Large Program mapping in the CO(2-1) line along with high-resolution Hi and Herschel dust continuum observations. Solving for GDR, XCO, and Kdark in macropixels 500 pc in size, each containing many individual measurements of the CO, Hi, and dust emission, we find that (i) allowing for CO dark gas (Kdark) significantly improves fits; (ii) Kdark decreases with galactocentric distance; (iii) GDR is slightly higher than initially expected and increases with galactocentric distance; (iv) the total amount of dark gas closely follows the radially decreasing CO emission, as might be expected if the dark gas is H2 where CO is photodissociated. The total amount of H2, including dark gas, yields an average XCO of twice the galactic value of 2×1020 cm-2=Kkm s-1, with about 55% of this traced directly through CO. The rather constant fraction of dark gas suggests that there is no large population of diffuse H2 clouds (unrelated to GMCs) without CO emission. Unlike in large spirals, we detect no systematic radial trend in XCO, possibly linked to the absence of a radial decrease in CO line ratios. [ABSTRACT FROM AUTHOR]

Published
2017
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9. Millimeter and submillimeter excess emission in M 33 revealed by Planck and LABOCA.

Author

Hermelo, I., Relaño, M., Lisenfeld, U., Verley, S., Kramer, C., Ruiz-Lara, T., Boquien, M., Xilouris, E. M., and Albrecht, M.

Abstract

Context. Previous studies have shown the existence of an excess of emission at submillimeter (submm) and millimeter (mm) wavelengths in the spectral energy distribution (SED) of many low-metallicity galaxies. The so-called “submm excess”, whose origin remains unknown, challenges our understanding of the dust properties in low-metallicity environments. Aims. The goal of the present study is to model separately the emission from the star forming (SF) component and the emission from the diffuse interstellar medium (ISM) in the nearby spiral galaxy M 33 in order to determine whether both components can be well fitted using radiation transfer models or whether there is an excess of submm emission associated with one or both of them. Methods. We decomposed the observed SED of M 33 into its SF and diffuse components. Mid-infrared (MIR) and far-infrared (FIR) fluxes were extracted from Spitzer and Herschel data. At submm and mm wavelengths, we used ground-based observations from APEX to measure the emission from the SF component and data from the Planck space telescope to estimate the diffuse emission. Both components were separately fitted using radiation transfer models based on standard dust properties (i.e., emissivity index β = 2) and a realistic geometry. The large number of previous studies helped us to estimate the thermal radio emission and to constrain an important part of the input parameters of the models. Both modeled SEDs were combined to build the global SED of M 33. In addition, the radiation field necessary to power the dust emission in our modeling was compared with observations from GALEX, Sloan, and Spitzer. Results. Our modeling is able to reproduce the observations at MIR and FIR wavelengths, but we found a strong excess of emission at submm and mm wavelengths where the model expectations severely underestimate the LABOCA and Planck fluxes. We also found that the ultraviolet (UV) radiation escaping the galaxy is 70% higher than the model predictions. From the total mass of dust derived from our modeling and the mass of atomic and molecular gas measured with the VLA and the IRAM 30 m telescope, we determined a gas-to-dust mass ratio Gdust ∼ 100, significantly lower than the value expected from the subsolar metallicity of M 33. Conclusions. We discussed different hypotheses to explain the discrepancies found in our study (i.e., excess of emission at submm and mm wavelengths, deficit of UV attenuation, and abnormally low value of Gdust), concluding that different dust properties in M 33 is the most plausible explanation. [ABSTRACT FROM AUTHOR]

Published
2016
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10. Deriving physical parameters of unresolved star clusters.

Author

de Meulenaer, P., Narbutis, D., Mineikis, T., and Vansevičius, V.

Subjects
*OPEN clusters of stars, *GALAXY clusters, *ASTRONOMICAL photometry, *STELLAR initial mass function, *TRIANGULUM Galaxy
Abstract

Context. When trying to derive the star cluster physical parameters of the M33 galaxy using broad-band unresolved ground-based photometry, previous studies mainly made use of simple stellar population models, shown in the recent years to be oversimplified. Aims. In this study, we aim to derive the star cluster physical parameters (age, mass, and extinction; metallicity is assumed to be LMC-like for clusters with age below 1 Gyr and left free for older clusters) of this galaxy using models that take stochastic dispersion of cluster integrated colors into account. Methods. We use three recently published M33 catalogs of cluster optical broad-band photometry in standard UBVRI and in CFHT/MegaCam u*g'r'i'z' photometric systems. We also use near-infrared JHK photometry that we derive from deep 2MASS images. We derive the cluster parameters using a method that takes into account the stochasticity problem, presented in previous papers of this series. Results. The derived differential age distribution of the M33 cluster population is composed of a two-slope profile indicating that the number of clusters decreases when age gets older. The first slope is interpreted as the evolutionary fading phase of the cluster magnitudes, and the second slope as the cluster disruption. The threshold between these two phases occurs at ~300 Myr, comparable to what is observed in the M31 galaxy. We also model by use of artificial clusters the ability of the cluster physical parameter derivation method to correctly derive the two-slope profile for different photometric systems tested. [ABSTRACT FROM AUTHOR]

Published
2015
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11. Measuring star formation with resolved observations: the test case of M 33.

Author

Boquien, M., Calzetti, D., Aalto, S., Boselli, A., Braine, J., Buat, V., Combes, F., Israel, F., Kramer, C., Lord, S., Relaño, M., Rosolowsky, E., Stacey, G., Tabatabaei, F., van der Tak, F., van der Werf, P., Verley, S., and Xilouris, M.

Subjects
*STELLAR evolution, *TRIANGULUM Galaxy, *INTERSTELLAR reddening, *STARBURSTS, *GALACTIC redshift, *INTERSTELLAR medium
Abstract

Context. Measuring star formation on a local scale is important to constrain star formation laws. It is not clear yet, however, whether and how the measure of star formation is affected by the spatial scale at which a galaxy is observed. Aims. We wish to understand the impact of the resolution on the determination of the spatially resolved star formation rate (SFR) and other directly associated physical parameters such as the attenuation. Methods. We carried out a multi-scale, pixel-by-pixel study of the nearby galaxy M33. Assembling FUV, Hα, 8 μm, 24 μm, 70 μm, and 100 μm maps, we have systematically compared the emission in individual bands with various SFR estimators from a resolution of 33 pc to 2084 pc. Results. There are strong, scale-dependent, discrepancies of up to a factor 3 between monochromatic SFR estimators and Hα+24 μm. The scaling factors between individual IR bands and the SFR show a strong dependence on the spatial scale and on the intensity of star formation. Finally, strong variations of the differential reddening between the nebular emission and the stellar continuum are seen, depending on the specific SFR (sSFR) and on the resolution. At the finest spatial scales, there is little differential reddening at high sSFR. The differential reddening increases with decreasing sSFR. At the coarsest spatial scales the differential reddening is compatible with the canonical value found for starburst galaxies. Conclusions. Our results confirm that monochromatic estimators of the SFR are unreliable at scales smaller than 1 kpc. Furthermore, the extension of local calibrations to high-redshift galaxies presents non-trivial challenges because the properties of these systems may be poorly known. [ABSTRACT FROM AUTHOR]

Published
2015
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12. Evolution of the grain size distribution in galactic discs

Author

I. De Looze, K. C. Hou, Monica Relaño, R. C. Kennicutt, José M. Vílchez, Ute Lisenfeld, Ministerio de Economía y Competitividad (España), European Commission, Junta de Andalucía, Israel Science Foundation, and Ministerio de Ciencia, Innovación y Universidades (España)

Subjects
individual: NGC 628 [Galaxies], 010504 meteorology & atmospheric sciences, Metallicity, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, individual: M 33 [Galaxies], individual: M 101 [Galaxies], 0103 physical sciences, Galaxies: individual: M 33, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences, Cosmic dust, Physics, Galaxies: individual: NGC 628, Spiral galaxy, Galaxies: evolution, Astronomy and Astrophysics, Mass ratio, evolution [Galaxies], Astrophysics - Astrophysics of Galaxies, Grain size, Galaxy, Interstellar medium, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), Galaxies: individual: M 101, Spectral energy distribution, Astrophysics::Earth and Planetary Astrophysics, Dust extinction
Abstract

Context. Dust is formed out of stellar material and it is constantly affected by different mechanisms occurring in the interstellar medium. Depending on their size, the behaviour of dust grains vary under these mechanisms and, therefore, the dust grain size distribution evolves as part of the dust evolution itself. Following how the grain size distribution evolves is a difficult computing task that has only recently become the subject of consideration. Smoothed particle hydrodynamic (SPH) simulations of a single galaxy, together with cosmological simulations, are producing the first predictions of the evolution of dust grain size distribution. Aims. We compare, for the first time, the evolution of the dust grain size distribution as predicted by SPH simulations and results from observations. We are able to validate not only the predictions of the evolution of the small-to-large grain mass ratio (DS/DL) within a galaxy, but we also provide observational constraints for recent cosmological simulations that include the grain size distribution in the dust evolution framework. Methods. We selected a sample of three spiral galaxies with different masses: M 101, NGC 628, and M 33. We fitted the dust spectral energy distribution across the disc of each object and derived the abundance of the different grain types included in the dust model. We analysed how the radial distribution of the relative abundance of the different grain size populations changes over the whole disc within each galaxy. The DS/DL ratio as a function of the galactocentric distance and metallicity is directly compared to what has been predicted by the SPH simulations. Results. We find a good agreement between the observed radial distribution of DS/DL and what was obtained from the SPH simulations of a single galaxy. The comparison agrees with the expected evolutionary stage of each galaxy. We show that the central parts of NGC 628 at a high metallicity and with a high molecular gas fraction are mainly affected not only by accretion, but also by the coagulation of dust grains. The centre of M 33, having a lower metallicity and lower molecular gas fraction, presents an increase in the DS/DL ratio, demonstrating that shattering is very effective for creating a large fraction of small grains. Finally, the observational results provided by our galaxies confirm the general relations predicted by the cosmological simulations based on the two-grain size approximation. However, we also present evidence that the simulations could be overestimating the amount of large grains in high massive galaxies. © 2020 ESO., Acknowledgements. The authors would like to thank the referee, Prof. Takeuchi, for the very constructive comments that helped to improve the first version of the paper. MR and UL acknowledges support by the research projects AYA2014-53506-P and AYA2017-84897-P from the Spanish Ministerio de Economía y Competitividad and Junta de Andalucía Grant FQM108; support from the European Regional Development Funds (FEDER) is acknowledged. KCH is supported by the IAEC-UPBC joint research foundation (Grant No. 257) and Israel Science Foundation (Grant No. 1769/15). JVM acknowledges financial support from the State Agency for Research of the Spanish MCIU through the “Center of Excellence Severo Ochoa” award to the Instituto de Astrofísica FUNDING TEXT 2: de Andalucía (SEV-2017-0709). MR and UL thank to the Computational service PROTEUS at the Instituto Carlos I. This work was partially supported by the Spanish Ministerio de Economía y Competitividad under Grants AYA2016-79724-C4-4-P and AYA2016-79724-C4-3-P, and excellence project PEX2011-FQM-7058 of Junta de Andalucía (Spain). This research made use of APLpy, an open-source plotting package for Python hosted at http://aplpy.github. com of TOPCAT & STIL: Starlink Table/VOTable Processing Software of Matplotlib, a suite of open-source python modules that provide a framework for creating scientific plots.

Published
2020

13. Evolution of grain size distribution in galactic discs

Author

Ministerio de Economía y Competitividad (España), European Commission, Junta de Andalucía, Israel Science Foundation, Ministerio de Ciencia, Innovación y Universidades (España), Relaño, M., Lisenfeld, U., Hou, K.-C., De Looze, I., Vílchez Medina, José Manuel, Kennicutt, R. C., Ministerio de Economía y Competitividad (España), European Commission, Junta de Andalucía, Israel Science Foundation, Ministerio de Ciencia, Innovación y Universidades (España), Relaño, M., Lisenfeld, U., Hou, K.-C., De Looze, I., Vílchez Medina, José Manuel, and Kennicutt, R. C.

Abstract

Context. Dust is formed out of stellar material and it is constantly affected by different mechanisms occurring in the interstellar medium. Depending on their size, the behaviour of dust grains vary under these mechanisms and, therefore, the dust grain size distribution evolves as part of the dust evolution itself. Following how the grain size distribution evolves is a difficult computing task that has only recently become the subject of consideration. Smoothed particle hydrodynamic (SPH) simulations of a single galaxy, together with cosmological simulations, are producing the first predictions of the evolution of dust grain size distribution. Aims. We compare, for the first time, the evolution of the dust grain size distribution as predicted by SPH simulations and results from observations. We are able to validate not only the predictions of the evolution of the small-to-large grain mass ratio (DS/DL) within a galaxy, but we also provide observational constraints for recent cosmological simulations that include the grain size distribution in the dust evolution framework. Methods. We selected a sample of three spiral galaxies with different masses: M 101, NGC 628, and M 33. We fitted the dust spectral energy distribution across the disc of each object and derived the abundance of the different grain types included in the dust model. We analysed how the radial distribution of the relative abundance of the different grain size populations changes over the whole disc within each galaxy. The DS/DL ratio as a function of the galactocentric distance and metallicity is directly compared to what has been predicted by the SPH simulations. Results. We find a good agreement between the observed radial distribution of DS/DL and what was obtained from the SPH simulations of a single galaxy. The comparison agrees with the expected evolutionary stage of each galaxy. We show that the central parts of NGC 628 at a high metallicity and with a high molecular gas fraction are mainly af

Published
2020

14. Multi-scale radio-infrared correlations in M 31 and M 33: The role of magnetic fields and star formation.

Author

Tabatabaei, F. S., Berkhuijsen, E. M., Frick, P., Beck, R., and Schinnerer, E.

Subjects
*INTERSTELLAR magnetic fields, *STAR formation, *COSMIC rays, *SYNCHROTRON radiation, *GALAXIES, *WAVELETS (Mathematics)
Abstract

Interstellar magnetic fields and the propagation of cosmic ray electrons have an important impact on the radio-infrared (IR) correlation in galaxies. This becomes evident when studying different spatial scales within galaxies. We investigate the correlation between the IR and free-free/synchrotron radio continuum emission at 20 cm from the two local group galaxies M 31 and M 33 on spatial scales between 0.4 and 10 kpc. The multi-scale radio-IR correlations have been carried out using a wavelet analysis. The free-free and IR emission are correlated on all scales, but on some scales the synchrotron emission is only marginally correlated with the IR emission. The synchrotron-IR correlation is stronger in M 33 than in M 31 on small scales (<1 kpc), but it is weaker than in M 31 on larger scales. Taking the smallest scale on which the synchrotron-IR correlation exists as the propagation length of cosmic ray electrons, we show that the difference on small scales can be explained by the smaller propagation length in M 33 than in M 31. On large scales, the difference is due to the thick disk/halo in M 33, which is absent in M 31. A comparison of our data with data on NGC 6946, the LMC and M 51 suggests that the propagation length is determined by the ratio of ordered-to-turbulent magnetic field strength, which is consistent with diffusion of CR electrons in the ISM. As the diffusion length of CR electrons influences the radio-IR correlation, this dependence is a direct observational evidence of the importance of magnetic fields for the radio-IR correlation within galaxies. The star-formation rate per surface area only indirectly influences the diffusion length as it increases the strength of the turbulent magnetic field. [ABSTRACT FROM AUTHOR]

Published
2013
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15. Spectral energy distributions of H II regions in M 33 (HerN33es).

Author

Relaño, M., Verley, S., Pérez, I., Kramer, C., Calzetti, D., Xilouris, E. M., Boquien, M., Abreu-Vicente, J., Combes, F., Israel, F., Tabatabaei, F. S., Braine, J., Buchbender, C., Gonzalez, M., Gratier, P., Lord, S., Mookerjea, B., Quintana-Lacaci, G., and van der Werf, P.

Subjects
*SPECTRAL energy distribution, *ELECTRON density, *STAR clusters, *GALAXIES, *IONIZED gases
Abstract

Aims. Within the framework of the Herschel M 33 extended survey HerM33es and in combination with multi-wavelength data we study the spectral energy distribution (SED) of a set of H II regions in the Local Group galaxy M 33 as a function of the morphology. We analyse the emission distribution in regions with different morphologies and present models to infer the Ha emission measure observed for H II regions with well defined morphology. Methods. We present a catalogue of 119 Hu regions morphologically classified: 9 filled, 47 mixed, 36 shell, and 27 clear shell H ii regions. For each object we extracted the photometry at twelve available wavelength bands, covering a wide wavelength range from FUV-1516 Å (GALEX) to IR-250 pm (Herschel), and we obtained the SED for each object. We also obtained emission line profiles in vertical and horizontal directions across the regions to study the location of the stellar, ionised gas, and dust components. We constructed a simple geometrical model for the clear shell regions, whose properties allowed us to infer the electron density of these regions. Results. We find trends for the SEDs related to the morphology of the regions, showing that the star and gas-dust configuration affects the ratios of the emission in different bands. The mixed and filled regions show higher emission at 24 µm, corresponding to warm dust, than the shells and clear shells. This could be due to the proximity of the dust to the stellar clusters in the case of filled and mixed regions. The far-JR peak for shells and clear shells seems to be located towards longer wavelengths, indicating that the dust is colder for this type of object. The logarithmic 100 µm/7O µm ratio for filled and mixed regions remains constant over one order of magnitude in Ha and FUV surface brightness, while the shells and clear shells exhibit a wider range of values of almost two orders of magnitude. We derive dust masses and dust temperatures for each H LI region by fitting the individual SEDs with dust models proposed in the literature. The derived dust mass range is between 102-104 M⊙ and the cold dust temperature spans Tcold ~ 12-27K. The spherical geometrical model proposed for the Ha clear shells is confirmed by the emission profile obtained from the observations and is used to infer the electron density within the envelope: the typical electron density is 0.7 ± 0.3 cm-3, while filled regions can reach values that are two to five times higher. [ABSTRACT FROM AUTHOR]

Published
2013
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16. Dense gas in M33 (HerM33es).

Author

Buchbender, C., Kramer, C., Gonzalez-Garcia, M., Israel, F. P., García-Burillo, S., van der Werf, P., Braine, J., Rosolowsky, E., Mookerjea, B., Aalto, S., Boquien, M., Gratier, P., Henkel, C., Quintana-Lacaci, G., Verley, S., and van der Tak, F.

Subjects
*MOLECULAR clouds, *INTERSTELLAR molecules, *STAR formation, *STELLAR evolution, *GALAXY formation, *ASTRONOMICAL observatories
Abstract

Aims. We aim to better understand the emission of molecular tracers of the diffuse and dense gas in giant molecular clouds and the influence that metallicity, optical extinction, density, far-UV field, and star formation rate have on these tracers. Methods. Using the IRAM 30m telescope, we detected HCN, HCO+, 12CO, and 13CO in six GMCs along the major axis of M33 at a resolution of ∼114 pc and out to a radial distance of 3.4 kpc. Optical, far-infrared, and submillimeter data from Herschel and other observatories complement these observations. To interpret the observed molecular line emission, we created two grids of models of photon-dominated regions, one for solar and one for M33-type subsolar metallicity. Results. The observed HCO+/HCN line ratios range between 1.1 and 2.5. Similarly high ratios have been observed in the Large Magellanic Cloud. The HCN/CO ratio varies between 0.4% and 2.9% in the disk of M33. The 12CO/13CO line ratio varies between 9 and 15 similar to variations found in the diffuse gas and the centers of GMCs of the Milky Way. Stacking of all spectra allowed HNC and C2H to be detected. The resulting HCO+/HNC and HCN/HNC ratios of ∼8 and 6, respectively, lie at the high end of ratios observed in a large set of (ultra-)luminous infrared galaxies. HCN abundances are lower in the subsolar metallicity PDR models, while HCO+ abundances are enhanced. For HCN this effect is more pronounced at low optical extinctions. The observed HCO+/HCN and HCN/CO line ratios are naturally explained by subsolar PDR models of low optical extinctions between 4 and 10 mag and of moderate densities of n 3x 103-3x 104 cm-3, while the FUV field strength only has a small effect on the modeled line ratios. The line ratios are almost equally well reproduced by the solar-metallicity models, indicating that variations in metallicity only play a minor role in influencing these line ratios. [ABSTRACT FROM AUTHOR]

Published
2013
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17. A detailed view of a molecular cloud in the far outer disk of M 33: Molecular cloud formation in M 33.

Author

Braine, J., Gratier, P., Contreras, Y., Schuster, K. F., and Brouillet, N.

Subjects
*MOLECULAR clouds, *HYDROGEN, *GALAXIES, *TEMPERATURE, *INTERSTELLAR molecules
Abstract

The amount of H2 present in spiral galaxies remains uncertain, particularly in the dim outer regions and in low-metallicity environments. We present high-resolution CO(1-0) observations with the Plateau de Bure interferometer of the most distant molecular cloud in the local group galaxy M 33. The cloud is a single entity rather than a set of smaller clouds within the broad beam of the original single-dish observations. The interferometer and single-dish fluxes are very similar and the line widths are indistinguishable, despite the difference in beamsize. At a spatial resolution of 10 pc, beyond the optical radius of the M 33, the CO brightness temperature reaches 2.4 Kelvins. A virial mass estimate for the cloud yields a mass of 4.3 × 104 M☉ and a ratio N(H2)/ICO(1-0) ≃ 3.5×1020 cm-2/(K km s-1).While no velocity gradient is seen where the emission is strong, the velocity is redshifted to the extreme SW and blue-shifted to the far NE. If the orientation of the cloud is along the plane of the disk (i.e. not perpendicular), then these velocities correspond to slow infall or accretion. The rather modest infall rate would be about 2 × 10-4 M☉ yr-1. [ABSTRACT FROM AUTHOR]

Published
2012
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18. Giant molecular clouds in the Local Group galaxy M 33.

Author

Gratier, P., Braine, J., Rodriguez-Fernandez, N. J., Schuster, K. F., Kramer, C., Corbelli, E., Combes, F., Brouillet, N., van der Werf, P. P., and Röllig, M.

Subjects
*MOLECULAR clouds, *INTERSTELLAR molecules, *HIGH-velocity clouds (Astrophysics), *GALAXY clusters, *STELLAR luminosity function, LOCAL Group (Astronomy)
Abstract

We present an analysis of a systematic CO(2-1) survey at 12″ resolution covering most of the Local Group spiral M 33, which, at a distance of 840 kpc, is close enough for individual giant molecular clouds (GMCs) to be identified. The goal of this work is to study the properties of the GMCs in this subsolar metallicity galaxy. The CPROPS (Cloud PROPertieS) algorithm was used to identify 337 GMCs in M 33, the largest sample to date for an external galaxy. The sample is used to study the GMC luminosity function, or mass spectrum under the assumption of a constant N(H2) /ICO ratio. We find that n(L)dL ∝ L-2.0±0.1 for the entire sample. However, when the sample is divided into inner and outer disk samples, the exponent changes from 1.6 ± 0.2 in the center 2 kpc to 2.3 ± 0.2 for galactocentric distances larger than 2 kpc. On the basis of the emission in the FUV, Hα, 8 μm, and 24 μm bands, each cloud was classified in terms of its star-forming activity - no star formation or either embedded or exposed star formation (visible in FUV and Hα). At least one sixth of the clouds had no (massive) star formation, suggesting that the average time required for star formation to start is about one sixth of the total time for which the object is identifiable as a GMC. The clouds without star formation have significantly lower CO luminosities than those with star formation, whether embedded or exposed, a result that is presumably related to the lack of heating sources. Taking the cloud sample as a whole, the main non-trivial correlation is the decrease in cloud CO brightness (or luminosity) with galactocentric radius. The complete cloud catalog, including the CO and HI spectra and the CO contours overlaid on the FUV, Hα, 8 μm, and 24 μm images is presented in the appendix. [ABSTRACT FROM AUTHOR]

Published
2012
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19. Dust and gas power spectrum in M 33 (HERM33ES).

Author

Combes, F., Boquien, M., Kramer, C., Xilouris, E. M., Bertoldi, F., Braine, J., Buchbender, C., Calzetti, D., Gratier, P., Israel, F., Koribalski, B., Lord, S., Quintana-Lacaci, G., Relaño, M., Röllig, M., Stacey, G., Tabatabaei, F. S., Tilanus, R. P. J., Van der Tak, F., and Van der Werf, P.

Subjects
*WAVELENGTHS, *GALAXIES, *INTERSTELLAR medium, *KINEMATICS, *LARGE magellanic cloud, *MOLECULAR clouds, *PHOTOMETRY
Abstract

Power spectra of deprojected images of late-type galaxies in gas or dust emission are very useful diagnostics of the dynamics and stability of their interstellar medium. Previous studies have shown that the power spectra can be approximated as two power laws, a shallow one on large scales (larger than 500 pc) and a steeper one on small scales, with the break between the two corresponding to the line-of-sight thickness of the galaxy disk. The break separates the 3D behavior of the interstellar medium on small scales, controlled by star formation and feedback, from the 2D behavior on large scales, driven by density waves in the disk. The break between these two regimes depends on the thickness of the plane, which is determined by the natural self-gravitating scale of the interstellar medium. We present a thorough analysis of the power spectra of the dust and gas emission at several wavelengths in the nearby galaxy M 33. In particular, we use the recently obtained images at five wavelengths by PACS and SPIRE onboard Herschel. The wide dynamical range (2-3 dex in scale) of most images allows us to clearly determine the change in slopes from -1.5 to -4, with some variations with wavelength. The break scale increases with wavelength from 100 pc at 24 and 100 μm to 350 pc at 500 μm, suggesting that the cool dust lies in a thicker disk than the warm dust, perhaps because of star formation that is more confined to the plane. The slope on small scales tends to be steeper at longer wavelength, meaning that the warmer dust is more concentrated in clumps. Numerical simulations of an isolated late-type galaxy, rich in gas and with no bulge, such as M 33, are carried out to better interpret these observed results. Varying the star formation and feedback parameters, it is possible to obtain a range of power spectra, with two power-law slopes and breaks, that nicely bracket the data. The small-scale power-law does indeed reflect the 3D behavior of the gas layer, steepening strongly while the feedback smoothes the structures by increasing the gas turbulence. M 33 appears to correspond to a fiducial model with an SFR of ∼0.7 M☉/yr, with 10% supernovae energy coupled to the gas kinematics. [ABSTRACT FROM AUTHOR]

Published
2012
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20. The S2N2 metallicity calibrator and the abundance gradient of M 33.

Author

Viironen, K., Delgado-Inglada, G., Mampaso, A., Magrini, L., and Corradi, R. L. M.

Subjects
*GALAXIES, *ATMOSPHERIC ionization, *IONIZATION of gases, *REDSHIFT, *METAPHYSICAL cosmology, *ASTRONOMY
Abstract

We introduce the log(Hα/[S ii]λλ6717+6731) versus log(Hα/[N ii]λ6583) (S2N2) diagnostic diagram as a metallicity and ionization parameter indicator for H ii regions in external galaxies. The location of H ii regions in the S2N2 diagram was studied both empirically and theoretically. We found that, for a wide range of metallicities, the S2N2 diagram gives single-valued results in the metallicity–ionization parameter plane. We demonstrate that the S2N2 diagram is a powerful tool to estimate metallicities of high-redshift H ii galaxies. Finally, we derive the metallicity for 76 H ii regions in M 33 from the S2N2 diagram and calculate an O/H abundance gradient for this galaxy of −0.05 (±0.01) dex kpc−1. [ABSTRACT FROM AUTHOR]

Published
2007
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21. Accurate extragalactic distances and dark energy: anchoring the distance scale with rotational parallaxes.

Author

Olling, Rob P.

Subjects
*METAPHYSICAL cosmology, *EXTRAGALACTIC distances, *DARK energy, *PARALLAX, *GALAXY clusters
Abstract

We investigate how the current and future uncertainty on the Hubble constant affects the uncertainty in the equation of state (EOS) of dark energy (DE) ( w) and the total density of the Universe (Ωtot). We start with the approximate linear relations between the cosmological parameters as presented by Spergel et al., and use the s.e. propagation relations to estimate the effects of improving the cosmic microwave background (CMB) parameters as well as the Hubble constant ( H0) on our knowledge of the EOS of DE. Because we do not assume a flat universe, we also estimate the attainable accuracy on Ωtot and the spatial curvature of the Universe. In one limiting case, we assume that the constraints provided by additional data (galaxy clustering, weak lensing and so forth) do not improve significantly, while the error on the Hubble constant is decreased by a factor of up to 10. The other limiting case of significantly improved additional data with current H0 errors has been investigated by the Dark Energy Task Force (DETF). For the former scenario, we find that future improvements of the determination of the CMB hardly changes the accuracy with which the EOS and Ωtot are known, unless the Hubble constant can be measured with an accuracy of several per cent. The conclusion of the DETF is that the Hubble constant hardly matters if the additional data are sufficiently accurate. We find that a combination of moderate H0 improvements with moderately improved ‘other’ data might significantly constrain the evolution of DE, but at a reduced cost. We review in some detail several methods that might yield extragalactic distances with errors of the order of several per cent, where we focus on the current and future strengths and weaknesses of the methods. Specifically we review the following: the velocity field method, two maser methods, four light echo techniques, two binary star methods and the ‘rotational parallax’ (RP) technique. Because these methods substantially rely on geometry rather than astrophysics or cosmology, their results are quite robust. In particular we focus on the advantages of the RP technique which can provide accurate (1 per cent), single-step and bias-free distances to Local Group galaxies. These distances can be used to improve the zero-point for other distance indicators which in turn would then be able to determine the Hubble constant to greater accuracy than they currently do. Achieving an accuracy of a few per cent in the zero-point distances to M 31, M 33 and the Large Magellanic Cloud by the RP method requires radial velocities at the 10 km s−1 level and proper motions attainable by future astrometric missions such as SIM, GAIA and OBSS, or by future radio observatories such as the SKA. [ABSTRACT FROM AUTHOR]

Published
2007
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22. Gas and dust cooling along the major axis of M 33 (HerM33es)

Author

Paul van der Werf, Thomas Nikola, S. Anderl, Jonathan Braine, Markus Röllig, Frank P. Israel, Karl Schuster, Francoise Combes, Christof Buchbender, Emmanuel M. Xilouris, I. Hermelo, Martina C. Wiedner, Monica Relaño, Frank Bertoldi, Christian Henkel, Floris van der Tak, Fatemeh Tabatabaei, Carsten Kramer, Simon Verley, Médéric Boquien, Ministerio de Economía y Competitividad (España), European Commission, Junta de Andalucía, Instituto de RadioAstronomía Milimétrica (IRAM), Centre National de la Recherche Scientifique (CNRS), Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA), Max-Planck-Institut für Radioastronomie (MPIFR), 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), Plateforme Génomique de l'IBENS, Institut de biologie de l'ENS Paris (UMR 8197/1024) (IBENS), Département de Biologie - ENS Paris, École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut National de la Santé et de la Recherche Médicale (INSERM)-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)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Département de Biologie - ENS Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), Institut für Physik (Institut für Physik), Universität Potsdam, Leiden Observatory [Leiden], Universiteit Leiden [Leiden], Dpto. Fisica Teorica y del Cosmos, Universidad de Granada (UGR), Physikalisches Institut [Köln], Universität zu Köln, Federal Institute for Geosciences and Natural Resources (BGR), SRON Netherlands Institute for Space Research (SRON), Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA), 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), National Observatory of Athens (NOA), Astronomy, Institut de biologie de l'ENS Paris (IBENS), Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Département de Biologie - ENS Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Département de Biologie - ENS Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Galaxies: individual: M33, Infrared, ISM [Infrared], Continuum (design consultancy), FOS: Physical sciences, Context (language use), Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, 01 natural sciences, 7. Clean energy, individual: M33 [Galaxies], galaxies [Infrared], ISM [Galaxies], 0103 physical sciences, Absorption (electromagnetic radiation), 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Line (formation), Infrared: ISM, Luminous infrared galaxy, Physics, Spiral galaxy, 010308 nuclear & particles physics, Astronomy and Astrophysics, individual:M33 [Galaxies], Infrared: galaxies, Astrophysics - Astrophysics of Galaxies, galaxies: individual: M 33, Interstellar medium, Galaxies: ISM, 13. Climate action, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

Context. M 33 is a gas rich spiral galaxy of the Local Group. Its vicinity allows us to study its interstellar medium (ISM) on linear scales corresponding to the sizes of individual giant molecular clouds. Aims. We investigate the relationship between the two major gas cooling lines and the total infrared (TIR) dust continuum. Methods. We mapped the emission of gas and dust in M 33 using the far-infrared lines of [C ii] and [O i](63 µm) and the total infrared continuum. The line maps were observed with the PACS spectrometer on board the Herschel Space Observatory. These maps have 50 pc resolution and form a ∼370 pc wide stripe along its major axis covering the sites of bright H ii regions, but also more quiescent arm and inter-arm regions from the southern arm at 2 kpc galacto-centric distance to the south out to 5.7 kpc distance to the north. Full-galaxy maps of the continuum emission at 24 µm from Spitzer/MIPS, and at 70 µm, 100 µm, and 160 µm from Herschel/PACS were combined to obtain a map of the TIR. Results. TIR and [C ii] intensities are correlated over more than two orders of magnitude. The range of TIR translates to a range of far ultraviolet (FUV) emission of G0,obs ∼ 2 to 200 in units of the average Galactic radiation field. The binned [C ii]/TIR ratio drops with rising TIR, with large, but decreasing scatter. The contribution of the cold neutral medium to the [C ii] emission, as estimated from VLA H i data, is on average only 10%. Fits of modified black bodies to the continuum emission were used to estimate dust mass surface densities and total gas column densities. A correction for possible foreground absorption by cold gas was applied to the [O i] data before comparing it with models of photon dominated regions. Most of the ratios of [C ii]/[O i] and ([C ii]+[O i])/TIR are consistent with two model solutions. The median ratios are consistent with one solution at n ∼ 2 × 102 cm−3 , G0 ∼ 60, and a second low-FUV solution at n ∼ 104 cm−3 , G0 ∼ 1.5. Conclusions. The bulk of the gas along the lines-of-sight is represented by a low-density, high-FUV phase with low beam filling factors ∼1. A fraction of the gas may, however, be represented by the second solution., Spanish Ministerio de Economia y Competitividad AYA2014-53506-P AYA2017-84897-P, Junta de Andalucia FQM108, Junta de Andalucia, European Union (EU) SOMM17/6105/UGR, Spanish Ministry of Economy and Competitiveness (MINECO) AYA2016-76219-P, European Union (EU)

Published
2020
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23. Properties and rotation of molecular clouds in M 33

Author

Edvige Corbelli, Jonathan Braine, Karl Schuster, Pierre Gratier, Erik Rosolowsky, FORMATION STELLAIRE 2020, Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), AMOR 2020, Institut de RadioAstronomie Millimétrique (IRAM), and Centre National de la Recherche Scientifique (CNRS)

Subjects
Rotation period, Metallicity, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Rotation, 01 natural sciences, ISM: clouds, 0103 physical sciences, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Physics, stars: formation, 010308 nuclear & particles physics, Star formation, Molecular cloud, Astronomy and Astrophysics, Escape velocity, Astrophysics - Astrophysics of Galaxies, Galaxy, galaxies: individual: M 33, ISM: molecules, Rotational energy, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), Local Group, [SDU.ASTR.GA]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Galactic Astrophysics [astro-ph.GA], [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], galaxies: ISM
Abstract

The sample of 566 molecular clouds identified in the CO(2--1) IRAM survey covering the disk of M~33 is explored in detail.The clouds were found using CPROPS and were subsequently catalogued in terms of their star-forming properties as non-star-forming (A), with embedded star formation (B), or with exposed star formation C.We find that the size-linewidth relation among the M~33 clouds is quite weak but, when comparing with clouds in other nearby galaxies, the linewidth scales with average metallicity.The linewidth and particularly the line brightness decrease with galactocentric distance.The large number of clouds makes it possible to calculate well-sampled cloud mass spectra and mass spectra of subsamples.As noted earlier, but considerably better defined here, the mass spectrum steepens (i.e. higher fraction of small clouds) with galactocentric distance.A new finding is that the mass spectrum of A clouds is much steeper than that of the star-forming clouds.Further dividing the sample, this difference is strong at both large and small galactocentric distances and the A vs C difference is a stronger effect than the inner/outer disk difference in mass spectra.Velocity gradients are identified in the clouds using standard techniques.The gradients are weak and are dominated by prograde rotation; the effect is stronger for the high signal-to-noise clouds.A discussion of the uncertainties is presented.The angular momenta are low but compatible with at least some simulations.The cloud and galactic gradients are similar; the cloud rotation periods are much longer than cloud lifetimes and comparable to the galactic rotation period.The rotational kinetic energy is 1-2\% of the gravitational potential energy and the cloud edge velocity is well below the escape velocity, such that cloud-scale rotation probably has little influence on the evolution of molecular clouds., Accepted for publication in Astronomy and Astrophysics, 11 pages

Published
2018
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24. Dense gas in low-metallicity galaxies

Author

Sylvain Bontemps, Ph. André, Jonathan Braine, Hao Chen, Yoshito Shimajiri, Yu Gao, Carsten Kramer, FORMATION STELLAIRE 2017, Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Chinese Academy of Sciences [Changchun Branch] (CAS), Instituto de RadioAstronomía Milimétrica (IRAM), Centre National de la Recherche Scientifique (CNRS), Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), and 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)

Subjects
Metallicity, galaxies: individual: IC 10, FOS: Physical sciences, Astrophysics, 01 natural sciences, 0103 physical sciences, 010303 astronomy & astrophysics, Line (formation), Physics, stars: formation, 010308 nuclear & particles physics, Star formation, Molecular cloud, Local Group, Astronomy and Astrophysics, Astrophysics - Astrophysics of Galaxies, Galaxy, galaxies: individual: M 33, Stars, Dipole, 13. Climate action, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), [SDU.ASTR.GA]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Galactic Astrophysics [astro-ph.GA], [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], galaxies: individual: NGC 6822, galaxies: ISM
Abstract

Stars form out of the densest parts of molecular clouds. Far-IR emission can be used to estimate the Star Formation Rate (SFR) and high dipole moment molecules, typically HCN, trace the dense gas. A strong correlation exists between HCN and Far-IR emission, with the ratio being nearly constant, over a large range of physical scales. A few recent observations have found HCN to be weak with respect to the Far-IR and CO in subsolar metallicity (low-Z) objects. We present observations of the Local Group galaxies M33, IC10, and NGC6822 with the IRAM 30meter and NRO 45m telescopes, greatly improving the sample of low-Z galaxies observed. HCN, HCO$^+$, CS, C$_2$H, and HNC have been detected. Compared to solar metallicity galaxies, the Nitrogen-bearing species are weak (HCN, HNC) or not detected (CN, HNCO, N$_2$H$^+$) relative to Far-IR or CO emission. HCO$^+$ and C$_2$H emission is normal with respect to CO and Far-IR. While $^{13}$CO is the usual factor 10 weaker than $^{12}$CO, C$^{18}$O emission was not detected down to very low levels. Including earlier data, we find that the HCN/HCO$^+$ ratio varies with metallicity (O/H) and attribute this to the sharply decreasing Nitrogen abundance. The dense gas fraction, traced by the HCN/CO and HCO$^+$/CO ratios, follows the SFR but in the low-Z objects the HCO$^+$ is much easier to measure. Combined with larger and smaller scale measurements, the HCO$^+$ line appears to be an excellent tracer of dense gas and varies linearly with the SFR for both low and high metallicities., Comment: 9 pages, 13 figures, A&A in press

Published
2017
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25. Velocity resolved [C ii] spectroscopy of the center and the BCLMP 302 region of M 33 (HerM 33es)

Author

Bhaswati Mookerjea, Frank P. Israel, C. Kramer, P. van der Werf, F. F. S. van der Tak, Martina C. Wiedner, J. Braine, Carsten Henkel, Volker Ossenkopf, Markus Röllig, T. Nikola, foreign laboratories (FL), CERN [Genève], FORMATION STELLAIRE 2016, Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), KOSMA, I. Physikalisches Institut [Köln], Universität zu Köln = University of Cologne-Universität zu Köln = University of Cologne, SRON Netherlands Institute for Space Research (SRON), Observatoire de Paris, Université Paris sciences et lettres (PSL), 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), Universität zu Köln-Universität zu Köln, École normale supérieure - Paris (ENS Paris), and Astronomy

Subjects
H II region, Analytical chemistry, FOS: Physical sciences, Context (language use), Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, 01 natural sciences, ISM: clouds, Spectral line, photon-dominated region (PDR), 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Spectral resolution, Spectroscopy, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Line (formation), Physics, 010308 nuclear & particles physics, Astronomy and Astrophysics, Astrophysics - Astrophysics of Galaxies, Hiiregions, Galaxy, galaxies: individual: M 33, Interstellar medium, 13. Climate action, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), galaxies: star formation, [SDU.ASTR.GA]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Galactic Astrophysics [astro-ph.GA], galaxies: ISM
Abstract

We aim to understand the contribution of the ionized, atomic and molecular phases of the ISM to the [CII] emission from clouds near the dynamical center and the BCLMP302 HII region in the north of the nearby galaxy M33 at a spatial resolution of 50pc. We combine high resolution [CII] spectra taken with the HIFI spectrometer onboard the Herschel satellite with [CII] Herschel-PACS maps and ground-based observations of CO(2-1) and HI. All data are at a common spatial resolution of 50pc. Typically, the [CII] lines have widths intermediate between the narrower CO(2-1) and broader HI line profiles. We decomposed the [CII] spectra in terms of contribution from molecular and atomic gas detected in CO(2-1) and HI, respectively. We find that the relative contribution of molecular and atomic gas traced by CO(2-1) and HI varies depends mostly on the local physical conditions and geometry. We estimate that 11-60% and 5-34% of the [CII] intensities in the center and in BCLMP302, respectively, arise at velocities showing no CO(2-1) or HI emission and could arise in CO-dark molecular gas. The deduced strong variation in the [CII] emission not associated with CO and HI cannot be explained in terms of differences in A_v, far-ultraviolet radiation field, and metallicity between the two studied regions. Hence the relative amounts of diffuse (CO-dark) and dense molecular gas possibly vary on spatial scales smaller than 50pc. Based on the emission measure observed at radio wavelengths we estimate the contribution of ionized gas at a few positions to lie between 10-25%. The correlations between the intensities of tracers corresponding to the same velocity range as [CII], differ from the correlation derived from PACS data. The results in this paper emphasize the need for velocity-resolved observations to discern the contribution of different components of the ISM to [CII] emission. (abridged), Comment: Accepted for publication in A&A

Published
2016
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26. Dust properties in H II regions in M 33

Author

C. Kramer, I. De Looze, Jonathan Braine, M. Albrecht, Monica Relaño, Médéric Boquien, Manolis Xilouris, Ute Lisenfeld, Simon Verley, Johannes Staguhn, Attila Kovács, Robert C. Kennicutt, Enrique Pérez-Montero, I. Hermelo, National Science Foundation (US), Ministerio de Economía y Competitividad (España), Junta de Andalucía, Ministerio de Educación y Ciencia (España), European Commission, Dpto. Fisica Teorica y del Cosmos, Universidad de Granada = University of Granada (UGR), Departamento Física Teórica y del Cosmos, Instituto de Astrofísica de Andalucía (IAA), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC)-Consejo Superior de Investigaciones Científicas [Madrid] (CSIC)-Universidad de Granada = University of Granada (UGR), Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Instituto de RadioAstronomía Milimétrica (IRAM), Centre National de la Recherche Scientifique (CNRS), FORMATION STELLAIRE 2016, Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Institute for Astronomy, Astrophysics, Space Applications and Remote Sensing [Penteli] (IAASARS), National Observatory of Athens (NOA), School of Physics and Astronomy [Minneapolis], University of Minnesota [Twin Cities] (UMN), University of Minnesota System-University of Minnesota System, AUTRES, Universidad de Granada (UGR), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC)-Consejo Superior de Investigaciones Científicas [Madrid] (CSIC)-Universidad de Granada (UGR), 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), Consejo Superior de Investigaciones Científicas [Spain] (CSIC)-Consejo Superior de Investigaciones Científicas [Spain] (CSIC)-Universidad de Granada (UGR), and University of Minnesota [Twin Cities]

Subjects
INITIAL MASS FUNCTION, Astrophysics, 01 natural sciences, GIANT HII-REGIONS, H II regions, Astrophysics::Solar and Stellar Astrophysics, 010303 astronomy & astrophysics, Physics, individual: M 33 [galaxies], Infrared: ISM, extinction, ISM [infrared], Hiiregions, WOLF-RAYET STARS, bubbles [ISM], Galaxies: ISM, Spectral energy distribution, [SDU.ASTR.GA]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Galactic Astrophysics [astro-ph.GA], dust, Astrophysics::Earth and Planetary Astrophysics, ISM: bubbles, DWARF GALAXIES, NGC 604, Metallicity, INFRARED-EMISSION, Extinction (astronomy), FOS: Physical sciences, Context (language use), M 33 HERM33ES, Astrophysics::Cosmology and Extragalactic Astrophysics, 0103 physical sciences, Galaxies: individual: M 33, Astrophysics::Galaxy Astrophysics, Dust, extinction, Cosmic dust, ISM [galaxies], 010308 nuclear & particles physics, Star formation, INTERSTELLAR RADIATION-FIELD, Astronomy and Astrophysics, Astrophysics - Astrophysics of Galaxies, Galaxy, Interstellar medium, Physics and Astronomy, 13. Climate action, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), MOLECULAR CLOUDS, LARGE-MAGELLANIC-CLOUD
Abstract

Context. The infrared emission (IR) of the interstellar dust has been claimed to be a tracer of the star formation rate. However, the conversion of the IR emission into star formation rate can be strongly dependent on the physical properties of the dust, which are a ected by the environmental conditions where the dust is embedded. Aims. We study here the dust properties of a set of Hii regions in the Local Group galaxy M33 presenting different spatial configurations between the stars, gas, and dust to understand the dust evolution indierent environments. Methods. We modelled the spectral energy distribution (SED) of each region using the DustEM tool and obtained the mass relative to hydrogen for very small grains (VSG, YVSG), polycyclic aromatic hydrocarbons (YPAH), and big grains (BG, YBG). We furthermore performed a pixel-by-pixel SED modelling and derived maps of the relative mass of each grain type for the whole surface of the two most luminous Hii regions in M33, NGC 604 and NGC 595. Results. The relative mass of the VSGs (YVSG/YTOTAL) changes with the morphology of the region: YVSG/YTOTAL is a factor of ∼1.7 higher for Hii regions classified as filled and mixed than for regions presenting a shell structure. The enhancement in VSGs within NGC 604 and NGC 595 is correlated to expansive gas structures with velocities ≥50 km s. The gas-to-dust ratio derived for the Hii regions in our sample exhibits two regimes related to the Hi.H2 transition of the interstellar medium (ISM). Regions corresponding to the Hi diffuse regime present a gas-to-dust ratio compatible with the expected value if we assume that the gas-to-dust ratio scales linearly with metallicity, while regions corresponding to a H2 molecular phase present a flatter dust-gas surface density distribution. Conclusions. The fraction of VSGs can be affected by the conditions of the interstellar environment: strong shocks of ∼5090km s existing in the interior of the most luminous Hii regions can lead to fragmentation of BGs into smaller ones, while the more evolved shell and clear shell objects provide a more quiescent environment where reformation of dust BGs might occur. The gas-to-dust variations found in this analysis might imply that grain coagulation and/or gas-phase metal incorporation into the dust mass is occurring in the interior of the Hii regions in M33. © 2016 ESO., Part of this research has been supported by the PERG08-GA-2010-276813 from the EC. This work was partially supported by the Junta de Andalucia Grant FQM108 and Spanish MEC Grants, AYA-2011-24728 and AYA-2014-53506-P. EPM thanks Spanish MINECO grant AYA-2013-47742-C4-1-P of the Spanish Plan for Astronomy and Astrophysics. This work was in part supported through NSF ATI grant 1106284.

Published
2016
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27. The molecular gas mass of M33

Author

F. F. S. van der Tak, P. van der Werf, J. Braine, Martina C. Wiedner, K. F. Schuster, B. S. Koribalski, Pierre Gratier, Erik Rosolowsky, Markus Röllig, Bhaswati Mookerjea, C. Kramer, Francoise Combes, Fabrice Herpin, Daniela Calzetti, M. Boquien, Frank P. Israel, Fatemeh Tabatabaei, Carsten Henkel, Astronomy, AMOR 2017, Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), FORMATION STELLAIRE 2017, Institut de RadioAstronomie Millimétrique (IRAM), Centre National de la Recherche Scientifique (CNRS), University of British Columbia (UBC), PSA Peugeot-Citroen, PSA Peugeot Citroën (PSA), 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), Collège de France - Chaire Galaxies et cosmologie, Collège de France (CdF (institution)), Instituto de Radio Astronomía Milimétrica, Max-Planck-Institut für Radioastronomie (MPIFR), Department of Astronomy [Jeddah], King Abdulaziz University, foreign laboratories (FL), CERN [Genève], Physikalisches Institut [Köln], Universität zu Köln = University of Cologne, SRON Netherlands Institute for Space Research (SRON), École normale supérieure - Paris (ENS Paris), Chaire Galaxies et cosmologie, and Universität zu Köln

Subjects
Metallicity, ISM: structure, Large population, FOS: Physical sciences, Astrophysics, EXTENDED SURVEY HERM33ES, 01 natural sciences, STAR-FORMATION, CO-TO-H-2 CONVERSION FACTOR, 0103 physical sciences, NEARBY GALAXIES, Density ratio, DUST EMISSION, 010303 astronomy & astrophysics, ISM: general, Physics, M33, radio lines: ISM, HERSCHEL, Spiral galaxy, 010308 nuclear & particles physics, SUBMILLIMETER EXCESS, CLOUDS, Astronomy and Astrophysics, Astrophysics - Astrophysics of Galaxies, galaxies: individual: M 33, Stars, Formalism (philosophy of mathematics), 13. Climate action, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), Local Group, submillimeter: ISM, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Dust emission
Abstract

[Abridged] Do some environments favor efficient conversion of molecular gas into stars? To answer this, we need to be able to estimate the H2 mass. Traditionally, this is done using CO and a few assumptions but the Herschel observations in the FIR make it possible to estimate the molecular gas mass independently of CO. Previous attempts to derive gas masses from dust emission suffered from biases. Generally, dust surface densities, HI column densities, and CO intensities are used to derive a gas-to-dust ratio (GDR) and the local CO intensity to H2 column density ratio (XCO), sometimes allowing for an additional CO-dark gas component (Kdark). We tested earlier methods, revealing degeneracies among the parameters, and then used a Bayesian formalism to derive the most likely values for each of the parameters mentioned above as a function of position in the nearby low metallicity spiral galaxy M33. The data are from the IRAM 30m CO(2-1) line, high-resolution HI and Herschel dust continuum observations. Solving for GDR, XCO, and Kdark in macro pixels 500 pc in size, we find that (i) allowing for CO-dark gas significantly improves fits; (ii) Kdark decreases with galactocentric distance; (iii) GDR is slightly higher than initially expected and increases with galactocentric distance; (iv) the total amount of dark gas closely follows the radially decreasing CO emission, as might be expected if the dark gas is H2 where CO is photodissociated. The total amount of H2, including dark gas, yields an average XCO of twice the galactic value of 2e20 cm^-2/(K km/s), 55% of this traced directly through CO. The rather constant fraction of dark gas suggests that there is no large population of diffuse H2 clouds (unrelated to GMCs) without CO emission. Unlike in large spirals, we detect no systematic radial trend in XCO, possibly linked to the absence of a radial decrease in CO line ratios., Comment: Accepted for publication in Astronomy and Astrophysics

Published
2016
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28. Dust properties in H II regions in M 33

Author

National Science Foundation (US), Ministerio de Economía y Competitividad (España), Junta de Andalucía, Ministerio de Educación y Ciencia (España), European Commission, Relanõ, M., Kennicutt, R., Lisenfeld, U., Verley, S., Hermelo, I., Boquien, Médéric, Albrecht, M., Kramer, C., Braine, J., Pérez Montero, Enrique, De Looze, I., Xilouris, M., Kovács, A., Staguhn, J., National Science Foundation (US), Ministerio de Economía y Competitividad (España), Junta de Andalucía, Ministerio de Educación y Ciencia (España), European Commission, Relanõ, M., Kennicutt, R., Lisenfeld, U., Verley, S., Hermelo, I., Boquien, Médéric, Albrecht, M., Kramer, C., Braine, J., Pérez Montero, Enrique, De Looze, I., Xilouris, M., Kovács, A., and Staguhn, J.

Abstract

Context. The infrared emission (IR) of the interstellar dust has been claimed to be a tracer of the star formation rate. However, the conversion of the IR emission into star formation rate can be strongly dependent on the physical properties of the dust, which are a ected by the environmental conditions where the dust is embedded. Aims. We study here the dust properties of a set of Hii regions in the Local Group galaxy M33 presenting different spatial configurations between the stars, gas, and dust to understand the dust evolution indierent environments. Methods. We modelled the spectral energy distribution (SED) of each region using the DustEM tool and obtained the mass relative to hydrogen for very small grains (VSG, YVSG), polycyclic aromatic hydrocarbons (YPAH), and big grains (BG, YBG). We furthermore performed a pixel-by-pixel SED modelling and derived maps of the relative mass of each grain type for the whole surface of the two most luminous Hii regions in M33, NGC 604 and NGC 595. Results. The relative mass of the VSGs (YVSG/YTOTAL) changes with the morphology of the region: YVSG/YTOTAL is a factor of ∼1.7 higher for Hii regions classified as filled and mixed than for regions presenting a shell structure. The enhancement in VSGs within NGC 604 and NGC 595 is correlated to expansive gas structures with velocities ≥50 km s. The gas-to-dust ratio derived for the Hii regions in our sample exhibits two regimes related to the Hi.H2 transition of the interstellar medium (ISM). Regions corresponding to the Hi diffuse regime present a gas-to-dust ratio compatible with the expected value if we assume that the gas-to-dust ratio scales linearly with metallicity, while regions corresponding to a H2 molecular phase present a flatter dust-gas surface density distribution. Conclusions. The fraction of VSGs can be affected by the conditions of the interstellar environment: strong shocks of ∼5090km s existing in the interior of the most luminous Hii regions can lead to fragme

Published
2016

29. The 2006 hot phase of Romano's star (GR 290) in M 33

Author

Roberto Viotti, Corinne Rossi, L. Norci, S. Galleti, R. Gualandi, F. Montagni, and V. F. Polcaro

Subjects
Brightness, stars: individual: gr 290, stars: wolf-rayet, FOS: Physical sciences, Context (language use), Astrophysics, Luminosity, Wolf–Rayet star, stars : variables : general, galaxies : individual : m 33, galaxies: individual: m 33, stars : early type, stars : evolution, stars : individual : gr 290, stars : wolf-rayet, stars: early-type, stars: evolution, stars: variables: general, Stellar evolution, Physics, Astrophysics (astro-ph), Astronomy and Astrophysics, Galaxy, Stars, Luminous blue variable, Space and Planetary Science
Abstract

Understanding the nature of the instabilities of LBVs is important to understand the late evolutionary stages of very massive stars. We investigate the long term, S Dor-type variability of the luminous blue variable GR290 (Romano's star) in M33, and its 2006 minimum phase. New spectroscopic and photometric data taken in November and December 2006 were employed in conjunction with already published data on GR290 to derive the physical structure of GR290 in different phases and the time scale of the variability. We find that by the end of 2006, GR 290 had reached the deepest visual minimum so far recorded. Its present spectrum resembles closely that of the Of/WN9 stars, and is the hottest so far recorded in this star (and in any LBV as well), while its visual brightness decreased by about 1.4 mag. This first spectroscopic record of GR290 during a minimum phase confirms that, similarly to AG Car and other LBVs, the star is subject to ample S Dor-type variations, being hotter at minimum, suggesting that the variations take place at constant bolometric luminosity., 4 figures, 1 table, accepted for publication in A&A Letters

Published
2007
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30. Dense Gas in M33 (HerM33es)

Author

F. F. S. van der Tak, Susanne Aalto, S. Verley, Frank P. Israel, Pierre Gratier, Carsten Henkel, Christof Buchbender, G. Quintana-Lacaci, Bhaswati Mookerjea, C. Kramer, Erik Rosolowsky, M. González-García, Santiago García-Burillo, Médéric Boquien, J. Braine, P. van der Werf, Instituto de RadioAstronomía Milimétrica (IRAM), Centre National de la Recherche Scientifique (CNRS), Observatorio Astronomico Nacional [Madrid] (OAN), Instituto Geografico Nacional (IGN), Leiden Observatory [Leiden], Universiteit Leiden [Leiden], FORMATION STELLAIRE 2013, 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), University of British Columbia (UBC), KOSMA, I. Physikalisches Institut, Universität zu Köln, Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7), Institut de RadioAstronomie Millimétrique (IRAM), Institut für Physik (Institut für Physik), Universität Potsdam, Dept. fısica Teorica y del Cosmos, Universidad de Granada (UGR), 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), 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), Observatorio Astronomico Nacional, Madrid, Universiteit Leiden, 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), Universität zu Köln = University of Cologne, Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), University of Potsdam = Universität Potsdam, Universidad de Granada = University of Granada (UGR), and 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)

Subjects
Metallicity, Milky Way, STAR-FORMING REGION, FOS: Physical sciences, Astrophysics, CHEMICAL-COMPOSITION, 01 natural sciences, ISM: clouds, Spectral line, COLOGNE DATABASE, MOLECULAR ABUNDANCE VARIATIONS, photon-dominated region (PDR), MAGELLANIC CLOUDS, 0103 physical sciences, 010306 general physics, Large Magellanic Cloud, 010303 astronomy & astrophysics, Line (formation), Luminous infrared galaxy, Physics, INTERSTELLAR-MEDIUM, Star formation, [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Molecular cloud, Astronomy and Astrophysics, INTER-STELLAR CLOUDS, [PHYS.ASTR.SR]Physics [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Astrophysics - Astrophysics of Galaxies, LUMINOUS INFRARED GALAXIES, LINE OBSERVATIONS, galaxies: individual: M 33, ISM: molecules, 13. Climate action, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), galaxies: ISM, LOCAL GROUP
Abstract

We aim to better understand the emission of molecular tracers of the diffuse and dense gas in giant molecular clouds and the influence that metallicity, optical extinction, density, far-UV field, and star formation rate have on these tracers. Using the IRAM 30m telescope, we detected HCN, HCO+, 12CO, and 13CO in six GMCs along the major axis of M33 at a resolution of ~ 114pc and out to a radial distance of 3.4kpc. Optical, far-infrared, and submillimeter data from Herschel and other observatories complement these observations. To interpret the observed molecular line emission, we created two grids of models of photon-dominated regions, one for solar and one for M33-type subsolar metallicity. The observed HCO+/HCN line ratios range between 1.1 and 2.5. Similarly high ratios have been observed in the Large Magellanic Cloud. The HCN/CO ratio varies between 0.4% and 2.9% in the disk of M33. The 12CO/13CO line ratio varies between 9 and 15 similar to variations found in the diffuse gas and the centers of GMCs of the Milky Way. Stacking of all spectra allowed HNC and C2H to be detected. The resulting HCO+/HNC and HCN/HNC ratios of ~ 8 and 6, respectively, lie at the high end of ratios observed in a large set of (ultra-)luminous infrared galaxies. HCN abundances are lower in the subsolar metallicity PDR models, while HCO+ abundances are enhanced. For HCN this effect is more pronounced at low optical extinctions. The observed HCO+/HCN and HCN/CO line ratios are naturally explained by subsolar PDR models of low optical extinctions between 4 and 10 mag and of moderate densities of n = 3x10^3 - 3x10^4 cm^-3, while the FUV field strength only has a small effect on the modeled line ratios. The line ratios are almost equally well reproduced by the solar-metallicity models, indicating that variations in metallicity only play a minor role in influencing these line ratios., Comment: 21 pages, 9 figures, published in A&A

Published
2013
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31. Dust emission from the atomic and molecular gas in M 33: a changing β

Author

Fatemeh Tabatabaei, Jonathan Braine, Manolis Xilouris, FORMATION STELLAIRE 2015, Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), and Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
010504 meteorology & atmospheric sciences, Stellar population, Metallicity, Milky Way, media_common.quotation_subject, ISM: Clouds, Astrophysics, 01 natural sciences, 0103 physical sciences, Emission spectrum, Galaxies: Local Group, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, media_common, Physics, Spiral galaxy, Astronomy, Astronomy and Astrophysics, Universe, Interstellar medium, Andromeda, Galaxies: ISM, Space and Planetary Science, Galaxies: Individual: M 33, [SDU]Sciences of the Universe [physics], [SDU.ASTR.GA]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Galactic Astrophysics [astro-ph.GA]
Abstract

We use the very recently completed high-resolution IRAM CO survey of M33 with the high-resolution HI observations (published by Gratier et al. 2010, A&A, 522, 3) and Herschel Far-IR and submillimeter mapping observations to study how the dust behaves in the molecular and atomic gas phases of the interstellar medium (ISM). M33 is a “young" object in that it is gas-rich with a young stellar population and low metallicity as compared to large spirals like the Milky Way or Andromeda. Nonetheless, it is very clearly a spiral galaxy with a thin and reasonably axisymmetric disk. As such, it can be viewed as a stepping stone towards less evolved objects like magellanic irregulars (including the LMC and SMC) and perhaps distant objects in the early universe. More specifically, we look for radial variations in the dust emission spectrum (β parameter) as well as comparing regions dominated by either H2 or HI. The grey-body emission spectrum flattens (lower β) with galactocentric distance and generally is flatter in the atomic medium as compared to the molecular gas.

Published
2012
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32. Dust and gas power-spectrum in M33 (HERM33ES)

Author

S. D. Lord, Fatemeh Tabatabaei, S. Verley, Frank P. Israel, Remo P. J. Tilanus, Baerbel Koribalski, P. van der Werf, C. Kramer, E. M. Xilouris, G. Quintana-Lacaci, J. Braine, M. Boquien, Francoise Combes, Frank Bertoldi, Christof Buchbender, D. Calzetti, M. Roellig, G. Stacey, F. F. S. van der Tak, Monica Relaño, Pierre Gratier, Kapteyn Astronomical Institute, Astronomy, 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), Department of Astronomy, University of Massachusetts System (UMASS), Instituto de RadioAstronomía Milimétrica (IRAM), Centre National de la Recherche Scientifique (CNRS), Max-Planck-Institut für Radioastronomie (MPIFR), 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), Leiden Observatory [Leiden], Universiteit Leiden [Leiden], 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), Dpto. Fisica Teorica y del Cosmos, Universidad de Granada (UGR), KOSMA, I. Physikalisches Institut [Köln], Universität zu Köln-Universität zu Köln, Dept. fısica Teorica y del Cosmos, Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Université 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), Universiteit Leiden, 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), Universidad de Granada = University of Granada (UGR), Universität zu Köln = University of Cologne-Universität zu Köln = University of Cologne, Laboratoire d'Astrophysique de Grenoble (LAOG), and Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
galaxies: spiral, Cosmology and Nongalactic Astrophysics (astro-ph.CO), FOS: Physical sciences, FLOCCULANT SPIRAL STRUCTURE, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, EXTENDED SURVEY HERM33ES, 01 natural sciences, Spectral line, STAR-FORMATION, DIFFUSE IONIZED-GAS, Bulge, 0103 physical sciences, DARK-MATTER, SMALL-MAGELLANIC-CLOUD, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Physics, 010308 nuclear & particles physics, Star formation, [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Spectral density, Astronomy and Astrophysics, Cosmology and Extragalactic Astrophysics, [PHYS.ASTR.SR]Physics [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], galaxies: general, Galaxy, galaxies: individual: M 33, NGC 891, GALACTIC NEUTRAL HYDROGEN, Interstellar medium, Wavelength, Supernova, Space and Planetary Science, Local Group, MOLECULAR CLOUDS, galaxies: structure, galaxies: ISM, Astrophysics - Cosmology and Nongalactic Astrophysics, H-I
Abstract

Power spectra of de-projected images of late-type galaxies in gas and/or dust emission are very useful diagnostics of the dynamics and stability of their interstellar medium. Previous studies have shown that the power spectra can be approximated as two power-laws, a shallow one at large scales (larger than 500 pc) and a steeper one at small scales, with the break between the two corresponding to the line-of-sight thickness of the galaxy disk. We present a thorough analysis of the power spectra of the dust and gas emission at several wavelengths in the nearby galaxy M33. In particular, we use the recently obtained images at five wavelengths by PACS and SPIRE onboard Herschel. The large dynamical range (2-3 dex in scale) of most images allow us to determine clearly the change in slopes from -1.5 to -4, with some variations with wavelength. The break scale is increasing with wavelength, from 100 pc at 24 and 100micron to 350 pc at 500micron, suggesting that the cool dust lies in a thicker disk than the warm dust, may be due to star formation more confined to the plane. The slope at small scale tends to be steeper at longer wavelength, meaning that the warmer dust is more concentrated in clumps. Numerical simulations of an isolated late-type galaxy, rich in gas and with no bulge, like M33, are carried out, in order to better interpret these observed results. Varying the star formation and feedback parameters, it is possible to obtain a range of power-spectra, with two power-law slopes and breaks, which nicely bracket the data. The small-scale power-law is indeed reflecting the 3D behaviour of the gas layer, steepening strongly while the feedback smoothes the structures, by increasing the gas turbulence. M33 appears to correspond to a fiducial model with an SFR of $\sim$ 0.7 Mo/yr, with 10% supernovae energy coupled to the gas kinematics., Comment: 11 pages, 24 figures, accepted in Astronomy & Astrophysics

Published
2012
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33. Spectrally resolved CII emission in M~33 ({\tt HerM33es}): Physical conditions and kinematics around BCLMP 691

Author

P. van der Werf, J. Braine, Pierre Gratier, F. F. S. van der Tak, M. Boquien, Frank P. Israel, Fatemeh Tabatabaei, C. Kramer, Carsten Henkel, Bhaswati Mookerjea, 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), Instituto de RadioAstronomía Milimétrica (IRAM), 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), 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), KOSMA, I. Physikalisches Institut, Universität zu Köln, 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), Department of Astronomy, University of Massachusetts System (UMASS), Institut für Physik (Institut für Physik), Universität Potsdam, Leiden Observatory [Leiden], Universiteit Leiden [Leiden], 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 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), Universität zu Köln = University of Cologne, Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), University of Potsdam = Universität Potsdam, Universiteit Leiden, Laboratoire d'Astrophysique de Grenoble (LAOG), and Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Cosmology and Nongalactic Astrophysics (astro-ph.CO), C+ EMISSION, FOS: Physical sciences, Astrophysics, PHOTODISSOCIATION REGIONS, 01 natural sciences, 7. Clean energy, ISM: clouds, STAR-FORMATION, CARBON, H-II REGIONS, MAGELLANIC CLOUDS, 0103 physical sciences, Continuum (set theory), Spectral resolution, 010303 astronomy & astrophysics, Heating efficiency, Line (formation), Physics, stars: formation, INTERSTELLAR-MEDIUM, 010308 nuclear & particles physics, [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Molecular cloud, Resolution (electron density), Astronomy and Astrophysics, [PHYS.ASTR.SR]Physics [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], galaxies: individual: M 33, MOLECULAR GAS, Interstellar medium, 13. Climate action, Space and Planetary Science, Local Group, galaxies: evolution, FAR-INFRARED SPECTROSCOPY, SPIRAL GALAXIES, galaxies: ISM, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

This work presents high spectral resolution observations of the \CII\ line at 158 \micron, one of the major cooling lines of the interstellar medium, taken with the HIFI heterodyne spectrometer on the Herschel satellite. In BCLMP 691, an \HII\ region far north (3.3 kpc) in the disk of M 33, the \CII\ and CO line profiles show similar velocities within $0.5 \kms$, while the \HI\ line velocities are systematically shifted towards lower rotation velocities by $\sim 5\kms$. Observed at the same $12"$ angular resolution, the \CII\ lines are broader than those of CO by about 50% but narrower than the \HI\ lines. The \CII\ line to far-infrared continuum ratio suggests a photoelectric heating efficiency of 1.1%. The data, together with published models indicate a UV field $G_0 \sim 100$ in units of the solar neighborhood value, a gas density $n_H \sim 1000 \cc$, and a gas temperature $T\sim 200$ K. Adopting these values, we estimate the C$^+$ column density to be $N_{C^+} \approx 1.3 \times 10^{17} \cmt$. The \CII\ emission comes predominantly from the warm neutral region between the \HII\ region and the cool molecular cloud behind it. From published abundances, the inferred C$^+$ column corresponds to a hydrogen column density of $N_H \sim 2 \times 10^{21} \cmt$. The CO observations suggest that $N_H = 2 N_{H_2} \sim 3.2 \times 10^{21} \cmt$ and 21cm measurements, also at $12"$ resolution, yield $N_\HI \approx 1.2 \times 10^{21} \cmt$ within the \CII\ velocity range. Thus, some H$_2$ not detected in CO must be present, in agreement with earlier findings based on the SPIRE 250 -- 500 $\mu$m emission., Comment: accepted in A&A

Published
2012
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34. The Herschel M 33 extended survey (HerM33es): PACS spectroscopy of the star forming region BCLMP 302 (Corrigendum)

Author

Susanne Aalto, Gordon J. Stacey, Carsten Henkel, S. D. Lord, Bhaswati Mookerjea, Santiago García-Burillo, Fatemeh Tabatabaei, J. Braine, Frank P. Israel, Francoise Combes, D. Calzetti, Médéric Boquien, G. Quintana-Lacaci, P. van der Werf, Simon Verley, Christof Buchbender, C. Kramer, van der Floris Tak, T. Nikola, Monica Relaño, Pierre Gratier, Markus Röllig, KOSMA, I. Physikalisches Institut, Universität zu Köln, Instituto de RadioAstronomía Milimétrica (IRAM), Centre National de la Recherche Scientifique (CNRS), Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7), Department of Astronomy, University of Massachusetts System (UMASS), Dept. fısica Teorica y del Cosmos, Universidad de Granada (UGR), Dpto. Fisica Teorica y del Cosmos, 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), Observatorio Astronomico Nacional [Madrid] (OAN), Instituto Geografico Nacional (IGN), Institut für Physik (Institut für Physik), Universität Potsdam, Leiden Observatory [Leiden], Universiteit Leiden [Leiden], 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), 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), Universität zu Köln = University of Cologne, Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Universidad de Granada = University of Granada (UGR), 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), Observatorio Astronomico Nacional, Madrid, University of Potsdam = Universität Potsdam, Universiteit Leiden, and 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)

Subjects
Scientific instrument, Physics, HII regions, 010308 nuclear & particles physics, [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Astronomy, Local Group, Astronomy and Astrophysics, Astrophysics, Star (graph theory), [PHYS.ASTR.SR]Physics [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], 01 natural sciences, Space observatory, local group, galaxies: individual: M 33, Interstellar medium, Space and Planetary Science, photon-dominated region (PDR), 0103 physical sciences, Far infrared spectroscopy, Spectroscopy, 010303 astronomy & astrophysics, addenda, galaxies: ISM, errata
Abstract

Accepted for publication in A&A. 12 pages, 12 figures 2011; International audience; Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.

Published
2012
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35. Erratum: The Herschel M 33 extended survey (HerM33es)

Subjects
HII regions, photon-dominated region (PDR), addenda, local group, galaxies: individual: M 33, galaxies: ISM, errata
Abstract

Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.

Published
2012
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36. Molecular and Atomic Gas in the Local Group Galaxy M33

Author

Wiedner, M., Bontemps, S., Henkel, C., Van Der Werf, P., Herpin, F., Van Der Tak, F., Rodriguez-Fernandez, N., Calzetti, D., Mookerjea, B., Gratier, P., Sievers, A., Brouillet, N., Israel, F., Henkel, Carsten, Schuster, K., Braine, J., Tabatabaei, F., Xilouris, E., Combes, F., Herpin, Fabrice, Garcia-Burillo, S., Corbelli, E., Wiklind, T., Koribalski, B., Roellig, M., Kramer, C., Aalto, S., Bontemps, Sylvain, 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), 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 Sciences et Technologies - Bordeaux 1, Laboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux (L3AB), Institut de RadioAstronomie Millimétrique (IRAM), Centre National de la Recherche Scientifique (CNRS), Instituto de RadioAstronomía Milimétrica (IRAM), Institut für Physik (Institut für Physik), Universität Potsdam, Leiden Observatory [Leiden], Universiteit Leiden [Leiden], Department of Astronomy, University of Massachusetts System (UMASS), Observatorio Astronomico Nacional [Madrid] (OAN), Instituto Geografico Nacional (IGN), 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), Onsala Space Observatory, Chalmers University of Technology [Göteborg], Australia Telescope National Facility, Australian National University (ANU), KOSMA, I. Physikalisches Institut [Köln], Universität zu Köln-Universität zu Köln, KOSMA, I. Physikalisches Institut, Universität zu Köln, 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), University of Potsdam = Universität Potsdam, Universiteit Leiden, Observatorio Astronomico Nacional, Madrid, École normale supérieure - Paris (ENS-PSL), Universität zu Köln = University of Cologne-Universität zu Köln = University of Cologne, Universität zu Köln = University of Cologne, and Astronomy

Subjects
Cosmology and Nongalactic Astrophysics (astro-ph.CO), Metallicity, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, ISM: clouds, STAR-FORMATION EFFICIENCY, 01 natural sciences, Luminosity, CO EMISSION, 0103 physical sciences, Surface brightness, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, M33, Physics, FORMATION HISTORY, stars: formation, Spiral galaxy, FORMING GALAXIES, 010308 nuclear & particles physics, Star formation, [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Molecular cloud, Astronomy and Astrophysics, Radius, Cosmology and Extragalactic Astrophysics, RADIO-CONTINUUM SURVEY, [PHYS.ASTR.SR]Physics [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], galaxies: individual: M 33, FAR-ULTRAVIOLET, Galaxy, SCHMIDT LAW, Space and Planetary Science, Local Group, galaxies: evolution, SPIRAL GALAXIES, galaxies: ISM, STELLAR POPULATION, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

We present high resolution large scale observations of the molecular and atomic gas in the Local Group Galaxy M33. The observations were carried out using the HERA at the 30m IRAM telescope in the CO(2-1) line achieving a resolution of 12"x2.6 km/s, enabling individual GMCs to be resolved. The observed region mainly along the major axis out to a radius of 8.5 kpc, and covers the strip observed with HIFI/PACS Spectrometers as part of the HERM33ES Herschel key program. The achieved sensitivity in main beam temperature is 20-50 mK at 2.6 km/s velocity resolution. The CO(2-1) luminosity of the observed region is 1.7\pm0.1x10^7 Kkm/s pc^2, corresponding to H2 masses of 1.9x10^8 Msun (including He), calculated with a NH2/ICO twice the Galactic value due to the half-solar metallicity of M33. HI 21 cm VLA archive observations were reduced and the mosaic was imaged and cleaned using the multi-scale task in CASA, yielding a series of datacubes with resolutions ranging from 5" to 25". The HI mass within a radius of 8.5 kpc is estimated to be 1.4x10^9 Msun. The azimuthally averaged CO surface brightness decreases exponentially with a scale length of 1.9\pm0.1 kpc whereas the atomic gas surface density is constant at Sigma_HI=6\pm2 Msun/pc^2 deprojected to face-on. The central kiloparsec H_2 surface density is Sigma_H2=8.5\pm0.2 Msun/pc^2. The star formation rate per unit molecular gas (SF Efficiency, the rate of transformation of molecular gas into stars), as traced by the ratio of CO to Halpha and FIR brightness, is constant with radius. The SFE appears 2-4 times greater than of large spiral galaxies. A morphological comparison of molecular and atomic gas with tracers of star formation shows good agreement between these maps both in terms of peaks and holes. A few exceptions are noted. Several spectra, including those of a molecular cloud situated more than 8 kpc from the galaxy center, are presented., Accepted for publication in A&A. Higher resolution version available at : http://www.obs.u-bordeaux1.fr/radio/gratier/M33_CO_HI_accepted.pdf

Published
2010
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37. Cool gas and dust in M33: Results from the Herschel M33 extended survey (HERM33ES)

Author

K. F. Schuster, Martina C. Wiedner, Bhaswati Mookerjea, G. Quintana-Lacaci, Susanne Aalto, Erik Rosolowsky, J. Braine, Fatemeh Tabatabaei, M. Gonzalez, B. S. Koribalski, P. van der Werf, C. Kramer, S. Verley, Carsten Henkel, F. F. S. van der Tak, Emmanuel M. Xilouris, Pierre Gratier, Frank P. Israel, Médéric Boquien, Monica Relaño, Christof Buchbender, Frank Bertoldi, Santiago García-Burillo, M. Roellig, Francoise Combes, D. Calzetti, 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), 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 Sciences et Technologies - Bordeaux 1 (UB), Laboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux (L3AB), Instituto de RadioAstronomía Milimétrica (IRAM), Centre National de la Recherche Scientifique (CNRS), Institute of Astronomy and Astrophysics, National Observatory of Athens (NOA), University of British Columbia (UBC), Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Department of Astronomy, University of Massachusetts System (UMASS), Institut für Physik (Institut für Physik), University of Potsdam = Universität Potsdam, Dept. fısica Teorica y del Cosmos, Universidad de Granada = University of Granada (UGR), Leiden Observatory [Leiden], Universiteit Leiden, SRON Netherlands Institute for Space Research (SRON), Max-Planck-Institut für Radioastronomie (MPIFR), TKK Helsinki University of Technology (TKK), 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), Observatorio Astronomico Nacional, Madrid, Fundación Venezolana de Investigaciones Sismológicas (FUNVISIS), FUNVISIS, Instituto de Ciencias de la Tierra, Universidad Central de Venezuela (UCV), Australia Telescope National Facility, Australian National University (ANU), KOSMA, I. Physikalisches Institut, Universität zu Köln = University of Cologne, KOSMA, I. Physikalisches Institut [Köln], Universität zu Köln = University of Cologne-Universität zu Köln = University of Cologne, Institut de RadioAstronomie Millimétrique (IRAM), Dpto. Fisica Teorica y del Cosmos, 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 ), 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 Sciences et Technologies - Bordeaux 1, Laboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux ( L3AB ), Instituto de RadioAstronomía Milimétrica ( IRAM ), Centre National de la Recherche Scientifique ( CNRS ), National Observatory of Athens ( NOA ), University of British Columbia ( UBC ), Astrophysique Interactions Multi-échelles ( AIM - UMR 7158 - UMR E 9005 ), Commissariat à l'énergie atomique et aux énergies alternatives ( CEA ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ) -Université Paris Diderot - Paris 7 ( UPD7 ), University of Massachusetts, Institut für Physik ( Institut für Physik ), Universität Potsdam, Universidad de Granada ( UGR ), Universiteit Leiden [Leiden], SRON Netherlands Institute for Space Research ( SRON ), Max-Planck-Institut für Radioastronomie ( MPIFR ), TKK Helsinki University of Technology, Helsinki University of Technology ( TKK ) -TKK, 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-Université de Cergy Pontoise ( UCP ), Université Paris-Seine-Université Paris-Seine-Centre National de la Recherche Scientifique ( CNRS ), Observatorio Astron ́omico Nacional (OAN), Observatorio de Madrid, Fundación Venezolana de Investigaciones Sismológicas ( FUNVISIS ), UNIVERSIDAD CENTRAL DE VENEZUELA, Australian National University ( ANU ), Universität zu Köln, Universität zu Köln-Universität zu Köln, Institut de RadioAstronomie Millimétrique ( IRAM ), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), 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), Universidad de Granada (UGR), 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), Observatorio Astronomico Nacional [Madrid] (OAN), Instituto Geografico Nacional (IGN), Astronomy, and École normale supérieure - Paris (ENS Paris)

Subjects
Systematic error, GRAPHITE, Cosmology and Nongalactic Astrophysics (astro-ph.CO), 010504 meteorology & atmospheric sciences, ISM: Clouds, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Measure (mathematics), 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Galaxies: Local Group, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences, Physics, [ PHYS.ASTR.SR ] Physics [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Molecular cloud, Galaxies: evolution, Astronomy and Astrophysics, galaxies: individual: M33, Mass ratio, [PHYS.ASTR.SR]Physics [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Galaxy, Spire, Galaxies: ISM, 13. Climate action, Space and Planetary Science, Galaxies: Individual: M 33, Content (measure theory), Local Group, Astrophysics::Earth and Planetary Astrophysics, Stars: Formation, [ SDU.ASTR.SR ] Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Astrophysics - Cosmology and Nongalactic Astrophysics, Dust emission
Abstract

We present an analysis of the first space-based far-IR-submm observations of M 33, which measure the emission from the cool dust and resolve the giant molecular cloud complexes. With roughly half-solar abundances, M33 is a first step towards young low-metallicity galaxies where the submm may be able to provide an alternative to CO mapping to measure their H$_2$ content. In this Letter, we measure the dust emission cross-section $\sigma$ using SPIRE and recent CO and \HI\ observations; a variation in $\sigma$ is present from a near-solar neighborhood cross-section to about half-solar with the maximum being south of the nucleus. Calculating the total H column density from the measured dust temperature and cross-section, and then subtracting the \HI\ column, yields a morphology similar to that observed in CO. The H$_2$/\HI\ mass ratio decreases from about unity to well below 10% and is about 15% averaged over the optical disk. The single most important observation to reduce the potentially large systematic errors is to complete the CO mapping of M 33., Comment: 5 pages, 5 figures Accepted for publication in Astronomy and Astrophysics

Published
2010
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38. The present status of four luminous variables in M 33

Author

Roberto Viotti, V. F. Polcaro, R. Gualandi, F. Montagni, Corinne Rossi, and L. Norci

Subjects
Physics, galaxies : individual : m 33, galaxies: individual: m 33, stars : evolution, stars : variables : general, stars: evolution, stars: variables: general, supergiants, Astrophysics::High Energy Astrophysical Phenomena, Astronomy, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Stellar classification, Luminosity, Stars, Space and Planetary Science, Astrophysics::Solar and Stellar Astrophysics, Emission spectrum, Supergiant, Yellow hypergiant, Variable star, Stellar evolution, Astrophysics::Galaxy Astrophysics
Abstract

Context. Understanding the origin of the instabilities of LBVs is important for shedding light on the late evolutionary stages of massive stars and on the chemical evolution of galaxies. Aims. To investigate the physical nature of variable stars in the upper H–R diagram, we performed a spectrophotometric study of the Romano’s star GR 290 and the Hubble-Sandage variables A, B, and C in the close galaxy M 33. Methods. New spectroscopic and photometric data were employed in conjunction with already published data of these stars in order to derive spectral types, energy distribution and bolometric luminosities. Results. The yellow hypergiant Var A is still at minimum, with a ∼G-type spectrum and strong Hα emission (Weq �− 35 A). Var B is in a low luminosity hot state (V = 17.5, B − V = −0.15) with very strong Hα emission (Weq = −310 A). Its absolute bolometric luminosity is 0.6 × 10 6 L� . Var C, at V = 16.4, is fainter than in the mid 1980s, but its spectrum shows the typical features of LBVs at maximum, a spectrum that is very rich in Fe ii emission lines. Its Lbol is about 0.7 × 10 6 L� . The Romano’s star GR 290 has a rich hot emission-line spectrum and is very bright with Lbol = 3 × 10 6 L� . During 2004 the star brightened by ∼half magnitude in each of the BVR filters. Conclusions. Our observations confirm that Var A probably is an intermediate type hypergiant star surrounded by an expanding envelope with a collisionally excited hydrogen emission, largely obscured by dusty disk and nebula. In recent years, Var B has undergone a blueward transition in the H–R diagram, probably at constant bolometric luminosity, while Var C is in a post-maximum phase with an η Car-type spectrum. GR 290 is notable for its spectrum and luminosity, and it is likely to develop ample spectral variations in the near future, similar to those observed in AG Car.

Published
2006

39. The LBV nature of Romano's star (GR 290) in M 33

Author

Polcaro V. F. 1, Gualandi R. 2, Norci L. 3, Rossi C. 4, and Viotti R. 5

Subjects
stars: individual: GR 290, Astrophysics::Solar and Stellar Astrophysics, stars: emission-lines, Astrophysics::Earth and Planetary Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, stars: evolution, stars: mass-loss, Astrophysics::Galaxy Astrophysics, galaxies: individual: M 33
Abstract

We report the first spectroscopic study of the LBV candidate GR 290 in M 33 (``Romano's star'') taken in February 2003, showing, besides prominent hydrogen and He I emission lines, the 4630-60 Å blend and weak He II 4686 Å emission typical of Of stars. Our broad-band photometry shows that the star was observed during a phase of minimum optical luminosity, with B=17.91+/- 0.03, and a slightly positive colour index, which we tentatively attribute to an anomalous continuum energy distribution. We argue that GR 290 is indeed an LBV star presently in a high temperature phase, that should be followed - also in a short time - by ample spectroscopic and associated photometric variations.

Published
2003

40. TheHerschelM 33 extended survey (HerM33es): PACS spectroscopy of the star-forming region BCLMP 302

Author

S. D. Lord, T. Nikola, Monica Relaño, P. van der Werf, Pierre Gratier, C. Kramer, Frank P. Israel, S. Verley, Bhaswati Mookerjea, Susanne Aalto, M. Boquien, J. Braine, F. F. S. van der Tak, M. Roellig, Santiago García-Burillo, Francoise Combes, Gordon J. Stacey, D. Calzetti, Carsten Henkel, Christof Buchbender, G. Quintana-Lacaci, Fatemeh Tabatabaei, KOSMA, I. Physikalisches Institut, Universität zu Köln, Instituto de RadioAstronomía Milimétrica (IRAM), Centre National de la Recherche Scientifique (CNRS), Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7), Department of Astronomy, University of Massachusetts System (UMASS), Dept. fısica Teorica y del Cosmos, Universidad de Granada (UGR), Dpto. Fisica Teorica y del Cosmos, 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'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), Laboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux (L3AB), Observatorio Astronomico Nacional [Madrid] (OAN), Instituto Geografico Nacional (IGN), Institut für Physik (Institut für Physik), Universität Potsdam, Leiden Observatory [Leiden], Universiteit Leiden [Leiden], 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), KOSMA, I. Physikalisches Institut [Köln], Universität zu Köln-Universität zu Köln, 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), Astronomy, Universität zu Köln = University of Cologne, Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Universidad de Granada = University of Granada (UGR), 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), Observatorio Astronomico Nacional, Madrid, University of Potsdam = Universität Potsdam, Universiteit Leiden, 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), and Universität zu Köln = University of Cologne-Universität zu Köln = University of Cologne

Subjects
HII regions, Spatial correlation, Photon, 010504 meteorology & atmospheric sciences, M33 HERM33ES, FOS: Physical sciences, Astrophysics, PHOTODISSOCIATION REGIONS, 01 natural sciences, PHOTON-DOMINATED REGIONS, H-II REGIONS, photon-dominated region (PDR), 0103 physical sciences, M EMISSION, NEARBY GALAXIES, PHYSICAL CONDITIONS, Emission spectrum, Spectroscopy, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, Physics, Spiral galaxy, INTERSTELLAR-MEDIUM, [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Molecular cloud, LONG-WAVELENGTH SPECTROMETER, Astronomy and Astrophysics, [PHYS.ASTR.SR]Physics [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Astrophysics - Astrophysics of Galaxies, galaxies: individual: M 33, Galaxy, Interstellar medium, 13. Climate action, Space and Planetary Science, galaxies: star formation, Astrophysics of Galaxies (astro-ph.GA), Local Group, FAR-INFRARED SPECTROSCOPY, galaxies: ISM, Galaxy Astrophysics
Abstract

Context: The emission line of [CII] at 158 micron is one of the strongest cooling lines of the interstellar medium (ISM) in galaxies. Aims: Disentangling the relative contributions of the different ISM phases to [CII] emission, is a major topic of the HerM33es program, a Herschel key project to study the ISM in the nearby spiral galaxy M33. Methods: Using PACS, we have mapped the emission of [CII] 158 micron, [OI] 63 micron, and other FIR lines in a 2'x2' region of the northern spiral arm of M33, centered on the HII region BCLMP302. At the peak of H-alpha emission, we have observed in addition a velocity resolved [CII] spectrum using HIFI. We use scatterplots to compare these data with PACS 160 micron continuum maps, and with maps of CO and HI data, at a common resolution of 12 arcsec or 50 pc. Maps of H-alpha and 24 micron emission observed with Spitzer are used to estimate the SFR. We have created maps of the [CII] and [OI] 63 micron emission and detected [NII] 122 micron and NIII 57 micron at individual positions. Results: The [CII] line observed with HIFI is significantly broader than that of CO, and slightly blue-shifted. In addition, there is little spatial correlation between [CII] observed with PACS and CO over the mapped region. There is even less spatial correlation between [CII] and the atomic gas traced by HI. Detailed comparison of the observed intensities towards the HII region with models of photo ionization and photon dominated regions, confirms that a significant fraction, 20--30%, of the observed [CII] emission stems from the ionized gas and not from the molecular cloud. The gas heating efficiency, using the ratio between [CII] and the TIR as a proxy, varies between 0.07 and 1.5%, with the largest variations found outside the HII region., Comment: Accepted for publication in A&A. 12 pages, 12 figures

Published
2011
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41. Dust emission from the atomic and molecular gas in M 33: a changing β.

Author

Braine, Jonathan, Tabatabaei, Fatemeh, Xilouris, Manolis, and Montmerle, Thierry

Abstract

We use the very recently completed high-resolution IRAM CO survey of M33 with the high-resolution HI observations (published by Gratier et al. 2010, A&A, 522, 3) and Herschel Far-IR and submillimeter mapping observations to study how the dust behaves in the molecular and atomic gas phases of the interstellar medium (ISM). M33 is a “young" object in that it is gas-rich with a young stellar population and low metallicity as compared to large spirals like the Milky Way or Andromeda. Nonetheless, it is very clearly a spiral galaxy with a thin and reasonably axisymmetric disk. As such, it can be viewed as a stepping stone towards less evolved objects like magellanic irregulars (including the LMC and SMC) and perhaps distant objects in the early universe. More specifically, we look for radial variations in the dust emission spectrum (β parameter) as well as comparing regions dominated by either H2 or HI. The grey-body emission spectrum flattens (lower β) with galactocentric distance and generally is flatter in the atomic medium as compared to the molecular gas. [ABSTRACT FROM PUBLISHER]

Published
2012
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42. The Herschel M 33 extended survey (HerM33es): PACS spectroscopy of the star forming region BCLMP302 (Corrigendum).

Author

Mookerjea, B., Kramer, C., Buchbender, C., Boquien, M., Verley, S., Relaño, M., Quintana-Lacaci, G., Aalto, S., Braine, J., Calzetti, D., Combes, F., Garcia-Burillo, S., Gratier, P., Henkel, C., Israel, F., Lord, S., Nikola, T., Röllig, M., Stacey, G., and Tabatabaei, F. S.

Subjects
STAR formation, ASTRONOMICAL spectroscopy
Abstract

A correction to the article "The Herschel M 33 extended survey (HerM33es): PACS spectroscopy of the star forming region BCLMP302" is presented.

Published
2012
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43. The chemical evolution of spiral galaxies: the Galaxy, M31, M33, M83 and M101

Author

Monica Tosi and Angeles I. Díaz

Subjects
Andromeda Galaxy, individual: M 83 [Galaxies], Astrophysics::High Energy Astrophysical Phenomena, Milky Way, Absolute value, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, individual: M 33 [Galaxies], Stellar nucleosynthesis, individual: M 101 [Galaxies], Galaxies: individual: M 33, Astrophysics::Solar and Stellar Astrophysics, Galaxies: individual: M 31, Stellar evolution, Astrophysics::Galaxy Astrophysics, spiral [Galaxies], Physics, Spiral galaxy, Física, Astronomy, Astronomy and Astrophysics, Galaxy, Abundance of the chemical elements, individual: M 31 [Galaxies], Space and Planetary Science, Galaxies: individual: M 101, Astrophysics::Earth and Planetary Astrophysics, Galaxies: spiral, Galaxies: individual: M 83
Abstract

One of the possible applications of stellar nucleosynthesis models is the study of the behaviour of chemical elements during the evolution of galaxies. The combination of correct models of stellar nucleosynthesis and of galactic evolution should allow to reproduce the observed properties of each element, in particular the absolute value and the radial distribution of the element abundance.

Published
1984
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