Molecular clouds associated with compact H II regions. III - Spin-up and collapse in the core of G10.6 - 0.4

Abstract

view Abstract Citations (104) References (27) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Molecular Clouds Associated with Compact H II Regions. III. Spin-up and Collapse in the Core of G10.6-0.4 Ho, P. T. P. ; Haschick, A. D. Abstract We report the successful aperture synthesis observations of the (J, K) = (1, 1) NH3 emission in the core of GlO.6 -0.4. For the first time, we think there is strong evidence to identify a collapsing molecular cloud core that is forming a central cluster of young massive stars. With 9" resolution, we find a rapidly rotating core with a velocity gradient of ∼ 10 km s-1 pc-1. This core region is embedded within a slowly rotating envelope with a gradient of ∼ 1 km s-1 pc-1 in the same sense as the core. There is an absorption feature redshifted by ∼ 5 km s-1 from the velocity centroid of the rotating core. We suggest that part of the core is also collapsing, perhaps in the direction of the central OB cluster. The combination of a rapidly rotating core, a slowly rotating envelope, evidence of collapse, and a central cluster of young stars suggests that we are seeing the spin-up of collapsing material while conserving angular momentum. We argue that spin-up motions may be an important new means to infer collapse, especially in regions where direct observations of collapse may not be easy or possible. The inferred accretion rate is high, >2 × 10-4 Msun yr-1, if the collapse is only onto the most compact continuum core, and even greater if the collapse is more extensive. Such accretion flows may restrain the rapid expansion of the embedded ultracompact H II regions. Publication: The Astrophysical Journal Pub Date: May 1986 DOI: 10.1086/164184 Bibcode: 1986ApJ...304..501H Keywords: Astronomical Spectroscopy; Gravitational Collapse; H Ii Regions; Molecular Clouds; Molecular Rotation; Stellar Mass Accretion; Absorption Spectra; Ammonia; Cores; Emission Spectra; Nebulae; Spectral Energy Distribution; Stellar Evolution; Astrophysics; INTERSTELLAR: MOLECULES; NEBULAE: H II REGIONS full text sources ADS | data products SIMBAD (1) Related Materials (2) Part 1: 1981ApJ...246..761H Part 2: 1985ApJ...293..522Z