The peculiar globular cluster system of the S0 galaxy NGC 7457.
CHOMIUK L., STRADER J. and BRODIE J.P.
Abstract (from CDS):
We present Hubble Space Telescope photometry and Keck spectroscopy of globular clusters (GCs) in the nearby S0 galaxy NGC 7457. The V - I color-magnitude diagram of GCs lacks the clear bimodality present in most early-type galaxies; there may be a significant population of intermediate-color objects. Of 13 spectroscopically observed GCs, two are unusually metal-rich and feature bright [O III] emission lines. We conclude that one probably hosts a planetary nebula and the other a supernova remnant. Such emission-line objects should be more common in an intermediate-age stellar population than in an old one. We therefore suggest that, in addition to the typical old metal-rich and old metal-poor GC subpopulations, there may be a third subpopulation of an intermediate age. Such a subpopulation may have been formed ∼2-3 Gyr ago, in the same star-forming event that dominates the stellar population of the center of the galaxy.
galaxies: individual: NGC 7457 - galaxies: interactions - galaxies: star clusters - planetary nebulae: general - supernova remnants