The Absolute Luminosities of the Calan/Tololo Type IA Supernovae

Abstract

We examine the absolute luminosities of 29 SNe Ia in the Calan/Tololo survey. We confirm a relation between the peak luminosity of the SNe and the decline rate as measured by the light curve, as suggested by Phillips [ApJ, 413, L105 (1993)]. We derive linear slopes to this magnitude- decline rate relation in BV(I)_KC_ colors, using a sample with B_MAX_ - V_MAX_ < 0.2^m^. The scatter around this linear relation (and thus the ability to measure SNe Ia distances) ranges from 0.13^m^ (in the I band) to 0.17^m^ (in the B band). We also find evidence for significant correlations between the absolute magnitudes or the decline rate of the light curve, and the morphological type of the host galaxy.