Dean Richardson

A Comparative Study of the Absolute Magnitude Distributions of Supernovae

The Asiago Supernova Catalog is used to carry out a comparative study of supernova absolute magnitude distributions. An overview of the absolute magnitudes of the supernovae in the current observational sample is presented, and the evidence for subluminous and overluminous events is examined. The fraction of supernovae that are subluminous (MB > -15) appears to be higher (perhaps much higher) than but it remains very uncertain. The fraction that are overluminous (MB > -20) is lower (probably much lower) than 0.01. The absolute magnitude distributions for each supernova type, restricted to events within 1 Gpc, are compared. Although these distributions are affected by observational bias in favor of the more luminous events, they are useful for comparative studies. We find mean absolute blue magnitudes (for H0 = 60) of -19.46 for normal Type Ia supernovae (SNe Ia), -18.04 for SNe Ibc, -17.61 and -20.26 for normal and bright SNe Ibc considered separately, -18.03 for SNe II-L, -17.56 and -19.27 for normal and bright SNe II-L considered separately, -17.00 for SNe II-P, and -19.15 for SNe IIn.

Absolute Magnitude Distributions and Light Curves of Stripped-Envelope Supernovae

The absolute visual magnitudes of three Type IIb, 11 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, prevent firm conclusions regarding differences between the absolute magnitudes of supernovae of Types 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 have had typical spectra. The light curves of stripped-envelope supernovae are collected and compared. Because SN 1994I in M51 was very well observed, it often is regarded as the prototypical Type Ic supernova, but it has the fastest light curve in the sample. Light curves are modeled by means of a simple analytical technique that, combined with a constraint on E/M from spectroscopy, yields internally consistent values of ejected mass, kinetic energy, and nickel mass.

Absolute Magnitude Distribution and Light Curves of Gamma-Ray Burst Supernovae

Photometry data were collected from the literature and analyzed for supernovae (SNe) that are thought to have a gamma-ray burst (GRB) association. There are several GRBs afterglow light curves that appear to have an SN component. For these light curves, the SN component was extracted and analyzed. An SN light-curve model was used to help determine the peak absolute magnitudes as well as estimates for the kinetic energy, ejected mass, and nickel mass in the explosion. The peak absolute magnitudes are, on average, brighter than those of similar SNe (stripped-envelope SNe) that do not have a GRB association, but this can easily be due to a selection effect. However, the kinetic energies and ejected masses were found to be considerably higher, on average, than those of similar SNe without a GRB association.

Mount Wilson and Palomar Photographic Supernova Spectra

Fifty-one photographic spectra of 20 bright supernovae that were obtained by J. L. Greenstein, R. Minkowski, and F. Zwicky at the Mount Wilson and Palomar Observatories between 1954 and 1970 are presented and briefly discussed. Microphotometer transmission tracings of the photographic plates have been digitized and plotted on a common wavelength scale. These spectra are useful for classification purposes and for comparative studies of the blueshifts of absorption features.

Lick Observatory Photographic Supernova Spectra

Seventy-eight photographic spectra of 18 bright supernovae that were obtained by various observers at the Lick Observatory between 1937 and 1971 are presented and briefly discussed. Microphotometer transmission tracings of the photographic plates have been digitized and plotted on a common scale with a linear wavelength axis. The spectra were prismatic, with a nonlinear dispersion, in their original form. These spectra are useful for classification purposes and for comparative studies of the blueshifts of absorption features.