------------------------------------------------------------------------
From: Dwarakanath  dwaraka@rri.res.in 
To: gcnews@aoc.nrao.edu
Subject: submit sgrawideline.tex JAA (accepted)


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%\slugcomment{submitted to the Journal of Astrophysics and Astronomy}

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\begin{document}

\title{On the Origin of the Wide HI Absorption Line Toward Sgr A*}

\author{K. S. Dwarakanath,$^1$
	W. M. Goss,$^2$
	J. H. Zhao$^3$
	\& C. C. Lang$^4$
\affil{       $^1$Raman Research Institute, Sadashivanagar, Bangalore 560 
080 \\
       $^2$National Radio Astronomy Observatory, PO BOX O, Socorro, NM
87801\\
       $^3$Harvard-Smithsonian Center for Astrophysics, Cambridge, MA
02138 \\
       $^4$Department of Physics and Astronomy, University of Iowa, Iowa
City, IA 52242}

\maketitle

\begin{abstract}

We have imaged a region of $\sim$ 5' extent surrounding Sgr A*
in the HI 21 cm-line absorption using the Very Large Array.
A Gaussian decomposition of the optical depth
spectra at positions within of $\sim$ 2' ($\sim$ 5 pc at 8.5 kpc)
of Sgr A* detects a wide line underlying the many
narrow absorption lines. The wide line has a mean peak optical depth of
0.32 $\pm$ 0.12 centered at a mean velocity of V$_{lsr}$ = $-$4 $\pm$ 15 km
s$^{-1}$. The
mean full width at half maximum is 119 $\pm$ 42 km s$^{-1}$.
Such a wide line is absent in the spectra at positions beyond $\sim$ 2'
from Sgr A*. The position-velocity diagrams in optical depth reveal that
the
wide line originates in various components of the circumnuclear disk
(radius $\sim$ 1.3') surrounding Sgr A*. These components
contribute to the optical depth of the wide line in different velocity
ranges.
The position-velocity diagrams do not reveal any diffuse feature
which could be attributed
to a large number of HI clouds along the line of sight to Sgr A*.
Consequently, the wide line has no implications either to a global
population
of shocked HI clouds in the Galaxy or to the energetics of the
interstellar medium
as was earlier thought.

\end{abstract}

\begin{keywords}

Galaxy : nucleus -- radio lines : ISM

\end{keywords}