THE RADIO-EMISSION FROM THE TYPE-IC SUPERNOVA SN-1990B

We present radio observations of the Type Ic ('' helium-poor '' Type Ib) supernova SN 1990B in NGC 4568 made with the Very Large Array at 20, 6, 3.6, and 2 cm from 1990 February through 1990 October. We find that its radio properties are quite similar to those of the two previously known Type Ib radio supernovae, SN 1983N and SN 1984L, and clearly distinguishable from the radio emission from Type II radio supernovae such as SN 1979C and SN 1986J. Nevertheless, there appear to be smaller, albeit significant, differences in the radio emission and physical properties of Type Ic from Type Ib radio supernovae. We discuss the radio properties of SN 1990B in the context of progenitor models for the Types Ib/c supernovae and conclude that an interacting binary system origin remains the most promising model. Finally, we suggest that Type Ib, and perhaps Ib/c, radio supernovae may form a class of radio '' standard candles '' which could be useful as distance indicators.