Journal Article

Massive star formation around IRAS 05345+3157 – I. The dense gas

Katherine I. Lee, Leslie W. Looney, Randolf Klein and Shiya Wang

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 415, issue 3, pages 2790-2797
Published in print August 2011 | ISSN: 0035-8711
Published online August 2011 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2011.18897.x
Massive star formation around IRAS 05345+3157 – I. The dense gas

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We present observations of the intermediate to massive star-forming region I05345+3157 using the molecular line tracer CS(2–1) with the Combined Array for Research in Millimetre-wave Astronomy to reveal the properties of the dense gas cores. Seven gas cores are identified in the integrated intensity map of CS(2–1). Among these, cores 1 and 3 have counterparts in the λ= 2.7 mm continuum data. We suggest that cores 1 and 3 are star-forming cores that may already or will very soon harbour young massive protostars. The total masses of core 1 estimated from the local thermodynamic equilibrium (LTE) method and dust emission by assuming a gas-to-dust ratio are 5 ± 1 and 18 ± 6 M, and that of core 3 are 15 ± 7 and 11 ± 3 M, respectively. The spectrum of core 3 shows blue-skewed self-absorption, which suggests gas infall – a collapsing core. The observed broad linewidths of the seven gas cores indicate non-thermal motions. These non-thermal motions can be interactions with nearby outflows or due to the initial turbulence; the former is observed, while the role of the initial turbulence is less certain. Finally, the virial masses of the gas cores are larger than the LTE masses, which, for a bound core, implies a requirement on the external pressure of ∼108 K cm−3. The cores have the potential to further form massive stars.

Keywords: techniques: interferometric; stars: formation; open clusters and associations: individual: IRAS 5345+3157; infrared: ISM; radio continuum: ISM; radio lines: ISM

Journal Article.  6407 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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