CONSTRAINING THE AGES OF SUPERNOVA PROGENITORS. I. SUPERNOVAE AND SPIRAL ARMS

摘要

We present the first results of a three-part study of supernova (SN) ages using positional age indicators in spiral galaxies. We have measured the positions of 90 spectroscopically identified Type Ⅰa and Type Ⅱ SNs (SNs Ⅰa and SNs Ⅱ) relative to spiral arms in their host galaxies, making a special effort to reduce inhomogeneity in the process of arm tracing for different galaxies. We find that SNs Ⅱ are more tightly concentrated to the arms than SNs Ⅰa, but both kinds of SNs occur closer to arms than a random disk population. However, when compared with the distribution of V and I light relative to the arms, the SNs Ⅰa are no more tightly concentrated than the general stellar population. This indicates that SNs Ⅰa occur in a population old enough to have diffused away from their formation regions.