Millimeter Dust Continuum Emission as a Tracer of Molecular Gas in Galaxies

Bot, Caroline; Boulanger, F.; Rubio, M.; Rantakyrö, Fredrik T.

doi:10.1007/978-0-387-72768-4_16

Cited by 3 publications

(6 citation statements)

References 6 publications

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“…If values of α ≪ 1 are not an artifact of our analysis technique, then there must be additional terms in the virial equation that are counteracting gravity. For instance, there may be a significant degree of magnetic support for the clumps, as suggested by Bot et al (2007) for clouds in the Small Magellanic Cloud with similarly low values of α. In this scenario, one would still need to explain why the α-M relation shows a smooth variation from the pressure-confined regime (α > 1) to the magnetically supported regime (α < 1), and how a strong degree of magnetic support is maintained in the most massive clumps, where ambiopolar diffusion should be most effective because of lower ionisation fractions in more shielded regions of the cloud.…”

Section: Dynamical State Of the Clumpsmentioning

confidence: 97%

Molecular line mapping of the giant molecular cloud associated with RCW 106 – II. Column density and dynamical state of the clumps

Wong

Ladd

Brisbin

et al. 2008

Monthly Notices RAS

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We present a fully sampled C 18 O (1-0) map towards the southern giant molecular cloud (GMC) associated with the H II region RCW 106, and use it in combination with previous 13 CO (1-0) mapping to estimate the gas column density as a function of position and velocity. We find localized regions of significant 13 CO optical depth in the northern part of the cloud, with several of the high-opacity clouds in this region likely associated with a limb-brightened shell around the H II region G333.6−0.2. Optical depth corrections broaden the distribution of column densities in the cloud, yielding a lognormal distribution as predicted by simulations of turbulence. Decomposing the 13 CO and C 18 O data cubes into clumps, we find relatively weak correlations between size and linewidth, and a more sensitive dependence of luminosity on size than would be predicted by a constant average column density. The clump mass spectrum has a slope near −1.7, consistent with previous studies. The most massive clumps appear to have gravitational binding energies well in excess of virial equilibrium; we discuss possible explanations, which include magnetic support and neglect of time-varying surface terms in the virial theorem. Unlike molecular clouds as a whole, the clumps within the RCW 106 GMC, while elongated, appear to show random orientations with respect to the Galactic plane.

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Section: Dynamical State Of the Clumpsmentioning

confidence: 97%

Molecular line mapping of the giant molecular cloud associated with RCW 106 – II. Column density and dynamical state of the clumps

Wong

Ladd

Brisbin

et al. 2008

Monthly Notices RAS

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“…To obtain a clear picture of how scattered the cold interstellar material is in the general area of N33, we investigate the distribution of molecular clouds and known young stellar objects (YSOs) in the vicinity (∼ 200 pc) of N33. CO surveys of the SMC reveal a concentration of molecular clouds in the southern end of this galaxy (Fukui & Kawamura, 2010;Mizuno et al, 2001;Stanimirović et al, 2000Stanimirović et al, , 1999Blitz et al, 2007;Bolatto et al, 2007;Leroy et al, 2007;Bot et al, 2010). However, the available CO observations do not detect the N33 H ii region, maybe because of a lack of sensitivity or resolution or for other reasons.…”

Section: Discussionmentioning

confidence: 99%

“…The southern end of the SMC has the particularity of containing the highest concentration of molecular clouds, IRAS/Spitzer sources, and H i emission in this neighboring galaxy (Fukui & Kawamura, 2010; ⋆ Based on observations obtained at the European Southern Observatory, La Silla, Chile, Program 69.C-0286(A) and 69.C-0286(B). Mizuno et al, 2001;Stanimirović et al, 2000Stanimirović et al, , 1999Blitz et al, 2007;Bolatto et al, 2007;Leroy et al, 2007;Bot et al, 2010). However, higher spatial resolutions and more extended mappings, especially in CO observations, are required to precisely associate the molecular clouds of that part with individual H ii regions and study the interaction with massive stars.…”

Section: Introductionmentioning

confidence: 99%

An interesting candidate for isolated massive-star formation in the Small Magellanic Cloud

Selier

Heydari-Malayeri

Gouliermis

2011

A&A

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Context. The region of the Small Magellanic Cloud (SMC) with which this paper is concerned contains the highest concentration of IRAS/Spitzer sources, H i emission, and molecular clouds in this neighboring galaxy. However, it has been the target of very few studies, despite this evidence of star formation. Aims. We present the first detailed study of the compact H ii region N33 in the SMC by placing it in a wider context of massive star formation. Moreover, we show that N33 is a particularly interesting candidate for isolated massive star formation.Methods. This analysis is based mainly on optical ESO NTT observations, both imaging and spectroscopy, coupled with other archive data, notably Spitzer images (IRAC 3.6, 4.5, 5.8, and 8.0 μm) and 2MASS observations. Results. We derive a number of physical characteristics of the compact H ii region N33 for the first time. This gas and dust formation of 7. 4 (2.2 pc) in diameter is powered by a massive star of spectral type O6.5-O7 V. The compact H ii region belongs to a rare class of H ii regions in the Magellanic Clouds, called high-excitation blobs (HEBs). We show that this H ii region is not related to any star cluster. Specifically, we do not find any traces of clustering around N33 on scales larger than 10 (∼3 pc). On smaller scales, there is a marginal stellar concentration, the low density of which, below the 3σ level, does not classify it as a real cluster. We also verify that N33 is not a member of any large stellar association. Under these circumstances, N33 is also therefore attractive because it represents a remarkable case of isolated massive-star formation in the SMC. Various aspects of the relevance of N33 to the topic of massive-star formation in isolation are discussed.

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“…We have used the 1.2 mm millimeter dust emission to determine molecular masses and compared them to those obtained from CO observations. In the SMC, we have done this study in two regions, the bright HII region N66 (Perez 2006) and the SW region of the SMCBAR (Bot 2005;Bot et al 2006).…”

Section: The Molecular Gasmentioning

confidence: 99%

“…The dust 1.2 mm emission was obtained by subtracting the CO emission line contribution and the free-free emission at 1.2 mm deduced from published continuum radio observations. The dust emission was used to compute gas masses (Bot 2005, Bot et al 2006). These gas masses were compared to virial masses determined from the CO emission, obtained from the CO(1-0)observations of the region done in ESO/SEST Key Programme: CO in the Magellanic Clouds (Rubio et al 1993).…”

Section: The Smcbarmentioning

confidence: 99%

Dense molecular clouds and associated star formation in the Magellanic Clouds

Rubio¹

2006

Proc. IAU

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Multiwavelengths studies of massive star formation regions in the LMC and SMC reveal that a second generation of stars is being formed in dense molecular clouds located in the surroundings of the massive clusters. These dense molecular clouds have survived the action of massive star UV radiation fields and winds and they appear as compact dense H2 knots in regions of weak CO emission. Alternatively, we have found that large molecular clouds, probably remnants of the parental giant molecular clouds where the first generation of stars were formed, are suffering the interaction of the winds and UV radiation field in their surfaces in the direction of the central massive cluster or massive stars. These molecular regions show 1.2 mm continuum emission form cold dust and they show embedded IR sources as determined from deep ground base JHKs imaging. The distribution of young IR sources as determined from their Mid IR colors obtained by SPITZER concentrate in the maxima of CO and dust emission. IR spectroscopy of the embedded sources with high IR excess confirm their nature as massive young stellar objects (MYSO's). Our results are suggestive of contagious star formation where triggering and induced star formation could be taking place.

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Millimeter Dust Continuum Emission as a Tracer of Molecular Gas in Galaxies

Cited by 3 publications

References 6 publications

Molecular line mapping of the giant molecular cloud associated with RCW 106 – II. Column density and dynamical state of the clumps

Molecular line mapping of the giant molecular cloud associated with RCW 106 – II. Column density and dynamical state of the clumps

An interesting candidate for isolated massive-star formation in the Small Magellanic Cloud

Dense molecular clouds and associated star formation in the Magellanic Clouds

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