Optical spectroscopy of Type Ia supernovae

The supernova, (SN) group at the Harvard-Smithsonian Center for Astrophysics has been using the facilities of the F. L. Whipple Observatory to gather optical photometric and spectroscopic data on nearby supernovae for several years. The collection of spectra of Type Ia SNe is now large enough to allow a comprehensive analysis. I will present preliminary results from a study of a subsample of the CfA Type la spectroscopic database, with over 200 spectra of 31 Type la SNe. The SNe selected all have well-calibrated light curves and cover a, wide scope of luminosity classes. The epochs of observation range from fourteen days before maximum to fifty days past maximum. All of the spectra were obtained with the same instrument on the same telescope, and were reduced using the same techniques. With such a large, homogeneous data set, the spectroscopic similarities and differences among Type Ia SNe become readily apparent.