THE TYPE Ic SUPERNOVA 1994I IN M51: DETECTION OF HELIUM AND SPECTRAL EVOLUTION

Abstract

We present a series of spectra of SN 1994I in M51, starting 1 week prior to maximum brightness. The nebular phase began about 2 months after the explosion; together with the rapid decline of the optical light, this suggests that the ejected mass was small. Although lines of He I in the optical region are weak or absent, consistent with the Type Ic classification, we detect strong He I l10830 absorption during the first month past maximum. Thus, if SN 1994I is a typical Type Ic supernova, the atmospheres of these objects cannot be completely devoid of helium. The emission-line widths are smaller than predicted by the model of Nomoto and coworkers, in which the iron core of a low-mass carbon-oxygen star collapses. They are, however, larger than in Type Ib supernovae. Subject headings: binaries: close— stars: evolution— stars: mass loss — supernovae: general — supernovae: individual (SN 1994I, SN 1987M, SN 1984L)

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Cite this paper

@inproceedings{Filippenko1995THETI, title={THE TYPE Ic SUPERNOVA 1994I IN M51: DETECTION OF HELIUM AND SPECTRAL EVOLUTION}, author={Alexei V . Filippenko and Aaron J. Barth and Thomas Matheson and Lee Armus and Michael J. I. Brown and Brian R. Espey and Xiaoming Fan and Robert W. Goodrich and Luis C. Ho and VESA T. JUNKKARINEN and David C . Koo and Matthew D. Lehnert and Andre ́ R. Martel and JOSEPH M. MAZZARELLA and Joseph S. Miller and Graeme HM Smith and David Tytler and Gregory D. Wirth}, year={1995} }