A high-velocity molecular cloud near the center of the Galaxy

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. ¹²CO images taken with Nobeyama Radio Observatory (NRO) 45 m telescope showed that it is relatively compact (∼3 × 4 pc²) as well as having a very large velocity width (ΔV ≥ 100 km s^-1). The cloud has a virial mass about 1 order of magnitude larger than the LTE mass, 9 × 10⁴ M_⊙, indicating the cloud is apparently gravitationally unbound. New observations with the James Clerk Maxwell Telescope 15 m and the NRO 45 m telescopes 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 that have occurred within the last (3-5) × 10⁴ yr.