On the spectrum of the peculiar type Ia supernova 1997br and the nature of SN 1991T-like events

Li et al. presented extensive observational data on the peculiar Type la SN 1997br and showed that it resembled the well-known peculiar SN 1991T. We present some results of a direct analysis of the spectra of SN 1997br. We raise the question of whether the Fe III and Ni III features in the early spectra are produced by (54)Fe and (58)Ni rather than by (56)Fe and (56)Ni as usually assumed, and discuss the issue of whether SN 1991T-like events are more powerful versions of normal SNe la rather than a physically distinct subgroup of events. (C) 2002 Elsevier Science B.V. All rights reserved.