# THE COMPARISON OF PHYSICAL PROPERTIES DERIVED FROM GAS AND DUST IN A MASSIVE STAR-FORMING REGION

Battersby, C, Bally, J, Dunham, M, Ginsburg, A, Longmore, SN and Darling, J (2014) THE COMPARISON OF PHYSICAL PROPERTIES DERIVED FROM GAS AND DUST IN A MASSIVE STAR-FORMING REGION. ASTROPHYSICAL JOURNAL, 786 (2). ISSN 0004-637X

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## Abstract

We explore the relationship between gas and dust in a massive star-forming region by comparing the physical properties derived from each. We compare the temperatures and column densities in a massive star-forming Infrared Dark Cloud (G32.02+0.05), which shows a range of evolutionary states, from quiescent to active. The gas properties were derived using radiative transfer modeling of the (1,1), (2,2), and (4,4) transitions of NH3 on the Karl G. Jansky Very Large Array, while the dust temperatures and column densities were calculated using cirrus-subtracted, modified blackbody fits to Herschel data. We compare the derived column densities to calculate an NH3 abundance, χ$_{{\rm NH}_{3}}$ = 4.6 × 10–8. In the coldest star-forming region, we find that the measured dust temperatures are lower than the measured gas temperatures (mean and standard deviations T dust, avg ~ 11.6 ± 0.2 K versus T gas, avg ~ 15.2 ± 1.5 K), which may indicate that the gas and dust are not well-coupled in the youngest regions (~0.5 Myr) or that these observations probe a regime where the dust and/or gas temperature measurements are unreliable. Finally, we calculate millimeter fluxes based on the temperatures and column densities derived from NH3, which suggest that millimeter dust continuum observations of massive star-forming regions, such as the Bolocam Galactic Plane Survey or ATLASGAL, can probe hot cores, cold cores, and the dense gas lanes from which they form, and are generally not dominated by the hottest core.

Item Type: Article 0201 Astronomical And Space Sciences, 0305 Organic Chemistry, 0306 Physical Chemistry (Incl. Structural) Q Science > QB Astronomy Astrophysics Research Institute IOP PUBLISHING LTD Author 08 Jun 2016 09:29 12 Oct 2019 22:43 10.1088/0004-637X/786/2/116 https://researchonline.ljmu.ac.uk/id/eprint/3726

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