======================================================================== G C N E W S * Newsflash * - The Newsletter for Galactic Center Research - gcnews@mpifr-bonn.mpg.de http://www.mpifr-bonn.mpg.de/gcnews ======================================================================== Vol. 12, No. 18 Nov 20, 2000 Recently submitted papers: -------------------------- 1) Molecular Tracers of the Central 12 pc of the Galactic Center (Wright et al., ApJ) ------------------------------------------------------------------------ Email : acoil@pavo.berkeley.edu Title : Molecular Tracers of the Central 12 pc of the Galactic Center Author(s): Melvyn C. H. Wright(1), Alison L. Coil(1), Robeson S. McGary(2), Paul T.P. Ho(2) and Andrew.I.Harris(3) Institute: (1) Radio Astronomy Laboratory, University of California, Berkeley, CA 94720 E-mail: mwright@astro.berkeley.edu, acoil@astro.berkeley.edu (2) Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138 E-mail: rmcgary@cfa.harvard.edu, ho@cfa.harvard.edu (3) University of Maryland, E-mail: harris@astro.umd.edu Paper : ApJ, in press EPrint : astro-ph/0011331 Abstract: We have used the BIMA array to image the Galactic Center with a 19-pointing mosaic in HCN(1-0), HCO^+(1-0), and H 42 alpha emission with 5 km s^-1 velocity resolution and 13'' * 4'' angular resolution. The 5' field includes the circumnuclear ring (CND) and parts of the 20 and 50 km s^-1 clouds. HCN(1-0) and HCO^+ trace the CND and nearby giant molecular clouds while the H 42 alpha emission traces the ionized gas in Sgr A West. We find that the CND has a definite outer edge in HCN and HCO^+ emission at 45'' radius and appears to be composed of two or three distinct streams of molecular gas rotating around the nucleus. Outside the CND, HCN and HCO^+ trace dense clumps of high-velocity gas in addition to optically thick emission from the 20 and 50 km s^-1 clouds. A molecular ridge of compressed gas and dust, traced in NH_3 emission and self-absorbed HCN and HCO^+, wraps around the eastern edge of Sgr A East. Just inside this ridge are several arcs of gas which have been accelerated by the impact of Sgr A East with the 50 km s^-1 cloud. HCN and HCO^+ emission trace the extension of the northern arm of Sgr A West which appears to be an independent stream of neutral and ionized gas and dust originating outside the CND. Broad line widths and OH maser emission mark the intersection of the northern arm and the CND. Comparison to previous NH_3 and 1.2mm dust observations shows that HCN and HCO^+ preferentially trace the CND and are weaker tracers of the GMCs than NH_3 and dust. We discuss possible scenarios for the emission mechanisms and environment at the Galactic center which could explain the differences in these images. ------------------------------------------------------------------------ (Older versions of the Newsflash can be found at the gcnews web-page) ======================================================================== Edited by Angela Cotera Heino Falcke & Sera Markoff (cotera@as.arizona.edu) (hfalcke,smarkoff@mpifr-bonn.mpg.de) - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - For Abstract submission please send the (La)Tex file of your paper to gcnews@mpifr-bonn.mpg.de ========================================================================