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THE ONSET OF MASSIVE STAR FORMATION: THE EVOLUTION OF TEMPERATURE AND DENSITY STRUCTURE IN AN INFRARED DARK CLOUD

Battersby, C and Ginsburg, A and Bally, J and Longmore, SN and Dunham, M and Darling, J (2014) THE ONSET OF MASSIVE STAR FORMATION: THE EVOLUTION OF TEMPERATURE AND DENSITY STRUCTURE IN AN INFRARED DARK CLOUD. ASTROPHYSICAL JOURNAL, 787 (2). ISSN 0004-637X

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Abstract

We present new NH3 (1, 1), (2, 2), and (4, 4) observations from the Karl G. Jansky Very Large Array compiled with work in the literature to explore the range of conditions observed in young, massive star-forming regions. To sample the effects of evolution independent from those of distance/resolution, abundance, and large-scale environment, we compare clumps in different evolutionary stages within a single infrared dark cloud (IRDC), G32.02+0.06. We find that the early stages of clustered star formation are characterized by dense, parsec-scale filamentary structures interspersed with complexes of dense cores (<0.1 pc cores clustered in complexes separated by ~1 pc) with masses from about 10 to 100 M ☉. The most quiescent core is the most extended while the star forming cores are denser and more compact, showing very similar column density structure before and shortly after the onset of massive star formation, with peak surface densities Σ gsim 1 g cm–2. Quiescent cores and filaments show smoothly varying temperatures from 10 to 20 K, rising to over 40 K in star-forming cores. We calculate virial parameters for 16 cores and find that the level of support provided by turbulence is generally insufficient to support them against gravitational collapse (langαvirrang ~ 0.6). The star-forming filaments show smooth velocity fields, punctuated by discontinuities at the sites of active star formation. We discuss the massive molecular filament (M ~ 105 M ☉, length >60 pc) hosting the IRDC, hypothesizing that it may have been shaped by previous generations of massive stars.

Item Type: Article
Uncontrolled Keywords: 0201 Astronomical And Space Sciences, 0305 Organic Chemistry, 0306 Physical Chemistry (Incl. Structural)
Subjects: Q Science > QB Astronomy
Divisions: Astrophysics Research Institute
Publisher: IOP PUBLISHING LTD
Related URLs:
Date Deposited: 08 Jun 2016 09:38
Last Modified: 08 Jun 2016 09:38
DOI or Identification number: 10.1088/0004-637X/787/2/113
URI: http://researchonline.ljmu.ac.uk/id/eprint/3725

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