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Dynamical Collapse in W51 Massive Cores: NH 3 Observations

1997; IOP Publishing; Volume: 488; Issue: 1 Linguagem: Inglês

10.1086/304667

1538-4357

Qizhou Zhang, Paul T. P. Ho,

Astro and Planetary Science

We present high angular resolution (02-1'', ~1600-8000 AU) studies of the W51 H II region complex in the NH3 (J, K) = (1, 1), (2, 2), and (3, 3) inversion transitions. This region has been identified previously with spectroscopic signatures of gravitational collapse. In one of the infalling cores, W51e2, we detect radial infall of ~3.5 km s-1 at scales of ~1'' (0.04 pc) from the star. The inward motion in the core is nearly constant. A velocity gradient of ~4 km s-1 exists at scales <04. The velocity gradient, which maximizes in the east-west direction, increases inward in radius as r-1.2, which indicates rotation and spin-up of material during the course of collapse. The infall and rotational motions are comparable in the inner core close to the star.