2012ApJ...756..170Q -
Astrophys. J., 756, 170 (2012/September-2)
Forming an O star via disk accretion?
QIU K., ZHANG Q., BEUTHER H. and FALLSCHEER C.
Abstract (from CDS):
We present a study of outflow, infall, and rotation in a ∼105 L☉ star-forming region, IRAS 18360-0537, with Submillimeter Array and IRAM 30 m observations. The 1.3 mm continuum map shows a 0.5 pc dust ridge, of which the central compact part has a mass of ∼80 M☉ and harbors two condensations, MM1 and MM2. The CO (2-1) and SiO (5-4) maps reveal a biconical outflow centered at MM1, which is a hot molecular core (HMC) with a gas temperature of 320 ±50 K and a mass of ∼13 M☉. The outflow has a gas mass of 54 M ☉ and a dynamical timescale of 8x103 yr. The kinematics of the HMC are probed by high-excitation CH3 OH and CH3CN lines, which are detected at subarcsecond resolution and unveil a velocity gradient perpendicular to the outflow axis, suggesting a disk-like rotation of the HMC. An infalling envelope around the HMC is evidenced by CN lines exhibiting a profound inverse P Cygni profile, and the estimated mass infall rate, 1.5x10–3 M☉/yr, is well comparable to that inferred from the mass outflow rate. A more detailed investigation of the kinematics of the dense gas around the HMC is obtained from the 13CO and C18O (2-1) lines; the position-velocity diagrams of the two lines are consistent with the model of a free-falling and Keplerian-like rotating envelope. The observations suggest that the protostar of a current mass ∼10 M☉ embedded within MM1 will develop into an O star via disk accretion and envelope infall.
Abstract Copyright:
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Journal keyword(s):
ISM: jets and outflows - ISM: kinematics and dynamics - stars: early-type - stars: formation
Nomenclature:
[QZB2012] MMN (Nos MM1-MM2)
Simbad objects:
14
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