Absolute-magnitude distributions and light curves of stripped-envelope supernovae.

Abstract

The absolute visual magnitudes of three Type IIb, 10 Type Ib and 13 Type Ic supernovae (collectively known as stripped-envelope supernovae) are studied by collecting data on the apparent magnitude, distance, and interstellar extinction of each event. Weighted and unweighted mean absolute magnitudes of the combined sample as well as various subsets of the sample are reported. The limited sample size and the considerable uncertainties, especially those associated with extinction in the host galaxies, still prevent firm conclusions regarding differences between the absolute magnitudes of supernovae of Type Ib and Ic, and regarding the existence of separate groups of overluminous and normal-luminosity stripped-envelope supernovae. The spectroscopic characteristics of the events of the sample are considered. Three of the four overluminous events are known to have had unusual spectra. Most but not all of the normal luminosity events had typical spectra.

The supernova data archive, SUSPECT, is presented. It is looked at, and mapped out, from the users point of view. The basic details of the operation of the database are also discussed.

Absolute light curves of stripped-envelope supernovae are collected and compared. They show a wide variety in peak brightness and light-curve width. These differences are reflected in the model parameter values determined. The supernova with the greatest kinetic energy (31 x 1051erg) and ejected mass (6.2 M⊙ ) in the sample is SN 1998bw. The hypernovae, in general, vary in peak brightness and therefore they vary in nickel mass. Supernova components found in gamma-ray burst afterglow light curves are modeled as well. These are treated as hypernovae and range in kinetic energy from 6.5 to 25 x 10 51erg. Two are found (GRB010921 and GRB011121) to have occurred more than a week before their associated gamma-ray burst.