OPTICAL SPECTRA OF 73 STRIPPED-ENVELOPE CORE-COLLAPSE SUPERNOVAE

Abstract

We present 645 optical spectra of 73 supernovae (SNe) of Types IIb, Ib, Ic,\nand broad-lined Ic. All of these types are attributed to the core collapse of\nmassive stars, with varying degrees of intact H and He envelopes before\nexplosion. The SNe in our sample have a mean redshift <cz> = 4200 km/s. Most of\nthese spectra were gathered at the Harvard-Smithsonian Center for Astrophysics\n(CfA) between 2004 and 2009. For 53 SNe, these are the first published spectra.\nThe data coverage range from mere identification (1-3 spectra) for a few SNe to\nextensive series of observations (10-30 spectra) that trace the spectral\nevolution for others, with an average of 9 spectra per SN. For 44 SNe of the 73\nSNe presented here, we have well-determined dates of maximum light to determine\nthe phase of each spectrum. Our sample constitutes the most extensive spectral\nlibrary of stripped-envelope SNe to date. We provide very early coverage (as\nearly as 30 days before V-band max) for photospheric spectra, as well as\nlate-time nebular coverage when the innermost regions of the SNe are visible\n(as late as 2 years after explosion, while for SN1993J, we have data as late as\n11.6 years). This data set has homogeneous observations and reductions that\nallow us to study the spectroscopic diversity of these classes of stripped SNe\nand to compare these to SNe associated with gamma-ray bursts. We undertake\nthese matters in follow-up papers.\n