A dense molecular ring surrounding the nonthermal Galactic center radio shell G359.1 - 0.5

The paper reports the detection of a dense nearly-continuous ring of molecular CO gas centered on, and concentric with, the nonthermal radio continuum shell G359.1 - 0.5. The molecular feature has radial velocities between -60 and -190 km/sec, indicating that it is likely to be located at the distance of the Galactic center. Its diameter is then about 75 pc. It is hypothesized that the expansion of CO ring was initiated by the winds, radiation, and supernova ejecta from a massive central cluster of O-type stars.