A while ago I had also a question on SN IIn and mailed it to Dr. Schlegel and he kindly replied with following answer: > To date, there is insufficient information to subdivide the IIn by light > curve. Some of the IIn fade very quickly (e.g., SN1987B) while others > remain bright for quite some time (e.g., SN1988Z, SN1995N). > > The IIn were originally defined by noting that quite a few supernovae > showed a narrow width to the H-alpha line (note: there are two senses > to the word 'narrow' in relation to IIn: the H-alpha line of IIn usually > shows a very narrow emission line that sits on top of a narrow base. The > very narrow portion of the line matches the line width of an H II region. > The use of 'narrow' for IIn describes the base portion which, while wider > than the H II-like emission core of the line, is considerably more narrow > than the width, at the base, of the H-alpha line of a normal Type II > supernova.) One of the first papers on SNe IIn was published by E.M. Schlegel 1990, Monthly Notices of the Royal Astronomical Society, 244, 269. This paper is available from ADS. Another paper on this subject which also deals with their possible association with being bright objects in radio wavelengths is published Van Dyk, et al. 1996, Astronomical Journal 111, p 1271 This paper is also available from ADS. A paper published by Cumming and Lunqvist is at available at http://xxx.lanl.gov/abs/astro-ph/9610023 (Thanks to Dr. Marcos Montes for directing to these references) Best Regards, Eric ------------------------------------------ VVS Werkgroep Veranderlijke Sterren Eric Broens Wateringstraat 143 B-2400 Mol BELGIUM E-Mail: eric.broens@ping.be ------------------------------------------