H I observations of elliptical galaxies.

Results are presented for 21-cm observations of 38 early-type galaxies, mostly ellipticals, performed with the 305-m Arecibo telescope with an efficiency corresponding roughly to 6 K/Jy. Six of the galaxies were detected, including only one 'normal' elliptical, NGC 4278. The results indicate that elliptical galaxies as a class contain very little neutral hydrogen, that some of the galaxies observed contain less than 1 part in 10,000 of their total mass in the form of neutral gas, and that the present gas content of an early-type galaxy is not related to the expected amount of mass lost over the history of the galaxy. Individual results are evaluated separately for the six galaxies detected in H I: NGC 3226-3227 (E2p, Sap), NGC 4278 (E1), NGC 7013 (S0/a), NGC 7332 (S0), NGC 7625 (Sa), and NGC 7742 (Sb). It is concluded that star formation is probably not taking place in ellipticals, that NGC 3226 and 7332 may contain gas due to accretion from their spiral neighbors, and that ellipticals may contain much of their mass in an extended halo of very low surface brightness.