DISK-OUTFLOW SYSTEM AROUND A MASSIVE PROTOSTAR
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Date
2005
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Ohio State University
Abstract
There are two major competing models for massive star formation: accretion via disks and coalescence of low-mass (proto)stars. The presence of well-defined disks around massive protostars may be the most convincing observational evidence to support the accretion model. We observed a massive protostar in the H$^{13}$CO$^+$ and H$^{13}$CN (1$-$0) lines and 3-mm continuum at 4$''$ resolution using the BIMA array, and detected a well-elongated dense condensation in the NE-SW direction. Dust continuum emission peaks around its center where a bright ($\sim$4$\times$10$^4$ $L_\odot$) IRAS point source is located. The condensation crosses the associated outflow axis at about 50$^irc$. A large ($\sim$15 km s$^{-1}$ pc$^{-1}$) velocity gradient exists along the major axis, suggesting rotation. The condensation has a size of 50000 AU and a mass of 400 $M_\odot$, which are very similar to those of the circumstellar disk recently detected around NGC 7538S. Therefore, this structure seems to be a circumstellar disk around a massive protostar, although further studies are required to confirm this.
Description
Author Institution: Department of Astronomy, University of Illinois, 1002 W. Grenn St., Urb; ana, IL 61801; Department of Astronomy, University of Wisconsin at Madison, 475 North; Charter St., Madison, WI 53705