TYPE IIN SUPERNOVAE - A SEARCH FOR RADIO-EMISSION

We have conducted a search using the Very Large Array for radio emissi on from members of Schlegel's (1990) proposed supernova subclass, Type IIn, which show optical characteristics indicative of shock interacti on with dense circumstellar matter. None has been detected to upper li mits of less than or similar to 0.2 mJy. We compare the corresponding radio luminosity upper limits for these supernovae to the radio lumino sities for known Type II radio supernovae. Although broadly similar op tically to the unusual Type IIn SNs 1988Z and 1986J, none of the obser ved supernovae could be nearly as radio luminous. We find that the rad io behavior of most Type IIn supernovae may not be significantly diffe rent from that of other more normal Type II supernovae. It therefore a ppears that optical spectra alone are not sufficient to predict radio luminosity and that intrinsically radio luminous supernovae, such as S Ns 1988Z and 1986J, are quite rare. (C) 1996 American Astronomical Soc iety.