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From: Farhad Zadeh  zadeh@northwestern.edu 
To: gcnews@aoc.nrao.edu
Subject: submission

\title{Massive Star Formation in the Molecular Ring Orbiting the 
Black Hole 
at the Galactic Center}
\author} Yusef-Zadeh, F.; Braatz, J.; Wardle, M.; Roberts, D.}
%arXiv:0807.1745
\begin{abstract}
A ring of dense molecular gas extending 2-7 pc orbits the supermassive black 
hole Sgr A* at the center of our Galaxy. Using the Green Bank Telescope, we 
detected water maser lines and both narrow (0.35 km/s) and broad (30 - 50 
km/s) methanol emission from the molecular ring. Two of the strongest methanol 
lines at 44 GHz are confirmed as masers by interferometric observations. These 
class I methanol masers are collisionally excited and are signatures of early 
phases of massive star formation in the disk of the Galaxy, suggesting that 
star formation in the molecular ring is in its early phase. Close inspection 
of the kinematics of the associated molecular clumps in the HCN (J=1-0) line 
reveals broad red-shifted wings indicative of disturbance by protostellar 
outflows from young (few times 10^4 yr), massive stars embedded in the clumps. 
The thermal methanol profile has a similar shape, with a narrow maser line 
superimposed on a broad, red-shifted wing. Additional evidence for the 
presence of young massive protostars is provided by shocked molecular hydrogen 
and a number of striking ionized and molecular linear filaments in the 
vicinity of methanol sources suggestive of 0.5-pc scale protostellar jets. 
Given that the circumnuclear molecular ring is kinematically unsettled and 
thus is likely be the result of a recent capture, the presence of both 
methanol emission and broad, red-shifted HCN emission suggests that star 
formation in the circumnuclear ring is in its infancy.
\end{abstract}