UC Berkeley

Using the Monte Carlo code SEDONA, multiband photometry and spectra are calculated for supernovae derived from stripped helium stars with presupernova masses of 2.2 to 10.0 M o˙. The models are representative of evolution in close binaries and have previously been exploded using a parameterized one-dimensional model for neutrino transport. A subset, those with presupernova masses in the range of 2.2-5.6 M o˙, have many properties in common with observed Type Ib and Ic supernovae, including a median ejected mass near 2 M o˙, explosion energies near 1 1051 erg, typical 56Ni masses of 0.07-0.09 M o˙, peak times of about 20 days, and a narrow range for the V - R color index 10 days post-V-maximum near 0.3 mag. The median peak bolometric luminosity, near 1042.3 erg s-1, is fainter, however, than several observational tabulations, and the brightest explosion has a bolometric luminosity of only 1042.50 erg s-1. The brightest absolute B, V, and R magnitudes at peak are -17.2, -17.8, and -18.0. These limits are fainter than some allegedly typical Type Ib and Ic supernovae and could reflect problems in our models or in the observational analysis. Helium stars with lower and higher masses also produce interesting transients that may have been observed, including fast, faint, blue transients and long, red, faint Type Ic supernovae. New models are specifically presented for SN 2007Y, SN 2007gr, SN 2009jf, LSQ 13abf, SN 2008D, and SN 2010X.