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. (C) 1996 American Astronomical Society.