The Stellar Content of the Post-Starburst S0 Galaxy NGC 5102

Abstract

The stellar content of the S0 galaxy NGC 5102 is investigated. A modest population of bright main sequence stars and red supergiants (RSGs) is detected throughout the western portion of the disk, and the star formation rate (SFR) during the past ten million years is estimated to have been 0.02 solar masses per year. RGB stars are traced out to galactocentric distances of 10 kpc, which corresponds to ~ 14 disk scale lengths. A large population of bright asymptotic giant branch (AGB) stars are seen throughout the western portion of the disk, and it is concluded that (1) stars that formed within the past Gyr comprise ~ 20% of the total stellar disk mass, and (2) the SFR during intermediate epochs in the disk of NGC 5102 was at least 1.4 solar masses per year. It is suggested that NGC 5102 was a spiral galaxy that experienced a galaxy-wide episode of enhanced star formation that terminated a few hundred Myr in the past, and that much of its interstellar medium was ejected in an outflow.