Presentation #110.01 in the session Large Scale Structure, Cosmic Distance Scale I.
The temperature of a supernova’s effective photosphere can be determined by calculating a chi-squared blackbody curve fit to the supernova’s continuum spectrum, or by using the photometery to calculate a color temperature. The Expanding Photosphere Method (EPM) uses the photosphere’s temperature in conjunction with its expansion velocity, as calculated from the Doppler shift of its spectral lines, to calculate the supernova’s distance. In this study, we look at a sample of sixteen supernovae, several of which have no previous EPM distance determinations. We use velocities derived from Fe and H-beta lines, and compare the distances calculated using blackbody temperature, B-V color temperature, and V-I color temperature. Since a supernova is not a perfect blackbody, we use correction factors derived by Hamuy et al. (2001) for Type II-P supernovae, and more recent correction factors derived by Dessart et al. (2015) for Type IIb/Ib/Ic supernovae.