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Search for CO emission in globular clusters

S. Leon , F. Combes
IRAM (Granada)
Observatoire de Paris (France)
Abstract: We have searched for CO(1-0) and CO(2-1) emission towards six globular clusters with the IRAM 30-m telescope. At a very low noise level (rms between 3 and 12 mK) we found no evidence of CO signals. Our derived 3 upper limits are below the solar mass for the molecular content of these objects, down to 0.07 M for NGC 5272. Since mass loss from AGB stars and post-turnoff stars should provide up to 100 M of intracluster gas between two disk crossings, we conclude that the gas must have been removed through ram-pressure stripping in a hot gaseous halo, as suggested by recent [OIII] and X-ray observations. For some clusters, however, the present hot gas density in the halo is not sufficient for efficient ram-pressure stripping.

Robert Lucas
Mon Sep 18 09:50:01 METDST 1995