Radio emission from hot stars at two centimeters

Radio fluxes of 7.2+-1.1 and 69+-5 mJy at 14.7 GHz have been detected from the stars zeta Pup (04If) and γ Vel (WC8+09I) respectively with the 64-m telescope at Parkes, and upper limits have been determined for 9 more hot stars. The interpretation of these fluxes as free-free emission from a shell of ionized gas resulting from a stellar wind gives mass-loss rates DM/dt=(6.5+-1.4)x10-6solar masses yr-1 for zeta Pup and (3.9+-0.7)x10-5 solar masses yr-1 for γ Vel if H/He=10 by number and the He is fully ionized. If the gas around γ Vel originates mainly from the WC8 star, the helium predominates and dM/dt=(5.2+-0.9)x10-5 or (17+-3)x10-5solar masses yr-1 depending on whether the helium is doubly or singly ionized. (Auth.)