From droberts@lai.ncsa.uiuc.edu Thu May  2 12:07:56 1996
Date: Thu, 02 May 1996 11:07:50 -0500
From: Doug Roberts <droberts@lai.ncsa.uiuc.edu>
Mime-Version: 1.0
To: gcnews@astro.umd.edu
Subject: to appear in the 4th ESO/CTIO Workshop on the Galactic Center Proceedings
X-Url: http://www.astro.umd.edu/~gcnews/submission.html

\documentstyle[11pt,paspconf,epsf]{article}

\def\about  {{$\sim$}}                     % About
\def\x      {$\times$}                          % Times symbol
\def\gt     {$>$}                               % >
\def\asec   {$^{\prime\prime}$}                 % Arcseconds symbol
\def\hnta   {H 92${\alpha}$} % H92alpha
\def\hii    {H II}           % HII
\def\hi     {H I}            % HI
\def\kms    {km s$^{-1}$}    % km/s
\def\msol   {$M_\odot$}                  % Solar mass
\def\sgras  {Sgr A*}                % Sgr A*

\begin{document}

\title{KINEMATICS OF THE IONIZED GAS IN SGR A WEST: THE MINICAVITY AND
THE WESTERN ARC}

\author{D.A. Roberts}
\affil{University of Illinois, NCSA, 405 N. Mathews Ave, Urbana, IL 61801}

\author{F. Yusef-Zadeh}
\affil{Northwestern University, Department of Physics and Astronomy,
  Evanston, IL 60208}

\author{W.M. Goss}
\affil{NRAO, P.O. Box 0, Socorro, NM 87801}

\begin{abstract}
The ``western arc'' and ``minicavity''(approximately 3{$^{\prime\prime}$}\ southwest
of {Sgr A*}) of the Galactic center {H II}\ region Sgr A West have been
imaged in the {H 92${\alpha}$}\ line at 8.3 GHz with the VLA.  The kinematics of
the ionized gas in the inner 1.5 parsecs of the Galactic center have
been determined.  The western arc, with an inner radius of 1 pc,
appears to be in circular rotation about a point near {Sgr A*}, with an
enclosed mass of {{$\sim$}} 3.5 {$\times$}\ 10$^6$ {$M_\odot$}.  Toward the minicavity, a
large velocity gradient ({$>$} 600 {km s$^{-1}$}\ pc$^{-1}$) is observed along the
eastern rim and uniformly large velocities are observed along the
western rim.  The velocity field of the minicavity is interpreted as
gas in a hyperbolic orbit about {Sgr A*}.  Based on this model, the gas
is orbiting a point at the position of {Sgr A*}\ with a mass of
{{$\sim$}}3.0 {$\times$}\ 10$^6$ {$M_\odot$}.
\end{abstract}

\end{document}