A High Velocity Cloud near the Center of the Galaxy

Abstract

We report the detection of a peculiar molecular cloud, CO 0.02-0.02, lying about 5' Galactic-east from the center of the Galaxy. (12)CO images taken with NRO 45 m telescope showed that it is relatively compact (about 3x4 pc^2) as well as having a very large velocity width (DV>=100 km s(-1)). The cloud has a virial mass about one order of magnitude larger than the LTE mass, 9E4 M(solar), indicating the cloud is apparently gravitationally unbound. New observations with the JCMT 15 m and the NRO 45 m telescope show that CO 0.02-0.02 is very bright in the CO J=3-2, and in the HCN and HCO+ J=1-0 lines. It appears that the environment may have an unusually high density and temperature, which may be related to the very broad CO line-width. We propose that CO 0.02-0.02 may have been accelerated, heated and compressed in a series of supernovae shocks which have occurred within the last (3-5)E4$ years.