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

Authors

  • Katherine I. Lee,

    Corresponding author
    1. Department of Astronomy, University of Illinois at Urbana-Champaign, 1002 W. Green Street, Urbana, IL 61801, USA
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  • Leslie W. Looney,

    1. Department of Astronomy, University of Illinois at Urbana-Champaign, 1002 W. Green Street, Urbana, IL 61801, USA
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  • Randolf Klein,

    1. SOFIA-USRA, NASA Ames Research Center, Mail Stop N211-3, Moffett Field, CA 94035, USA
    2. Department of Physics, University of California at Berkeley, 366 Le Conte Hall, Berkeley, CA 94720, USA
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  • Shiya Wang

    1. Department of Astronomy, University of Michigan at Ann Arbor, 500 Church Street, Ann Arbor, MI 48109, USA
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E-mail: ijlee9@illinois.edu

ABSTRACT

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.

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