The Type IC Supernova 1994I in M51: Detection of Helium and Spectral Evolution

September 1995 • 1995ApJ...450L..11F

Authors • Filippenko, Alexei V. • Barth, Aaron J. • Matheson, Thomas • Armus, Lee • Brown, Michael • Espey, Brian R. • Fan, Xiao-Ming • Goodrich, Robert W. • Ho, Luis C. • Junkkarinen, Vesa T. • Koo, David C. • Lehnert, Matthew D. • Martel, Andre R. • Mazzarella, Joseph M. • Miller, Joseph S. • Smith, Graeme H. • Tytler, David • Wirth, Gregory D.

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 lambda 10830 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.

Links

• SIMBAD http://simbad.u-strasbg.fr/simbo.pl?bibcode=1995ApJ...450L..11F
• NED https://ned.ipac.caltech.edu/uri/NED::InRefcode/1995ApJ...450L..11F
• GIF http://articles.adsabs.harvard.edu/full/1995ApJ...450L..11F
• ARTICLE http://articles.adsabs.harvard.edu/full/1995ApJ...450L..11F?defaultprint=YES