A SEARCH FOR CO(2-1) EMISSION FROM THE GLOBULAR-CLUSTER M15

A search for 230-GHz CO(2-1) emission in the direction of the globular cluster M15 has been made with the 15-m James Clerk Maxwell Telescope on Mauna Kea. A spectrum accumulated over a total integration time of 15 000 s shows no evidence of any CO(2-1) emission feature at the vel ocity of the cluster. The amount of gas that is expected to have been expelled by red giants into the intracluster environment since the mos t recent crossing of the Galactic plane by the cluster is in excess of 12 M(.). The upper limit placed on the mass of molecular gas in M15 b y the JCMT observation is similar to 0.4 M(.). The upper limit to the combined mass of interstellar dust, and molecular H-2, neutral HI and ionized HII gas within M15 that has been placed by observations is sim ilar to 3 M(.). Therefore some mechanism appears to have removed much of the expected interstellar medium from M15. In the particular case o f this cluster, energy sources that might have promoted gas loss inclu de ionizing radiation from X-ray binaries and UV-bright stars, and win ds from millisecond pulsars and M dwarfs.