An active debate continues over whether elliptical galaxies are primarily old stellar systems or whether they have had major star formation events in the recent past. Not only is this question of interest with regard to understanding the stellar populations and star formation history of nearby systems, but the resolution of this issue influences the interpretation of the spectra of high-redshift galaxies and has profound consequences for our understanding of galaxy, and therefore ultimately, of cosmological evolution.
Our lack of understanding of the stellar make-up in elliptical galaxies has persisted for some time because there are no giant elliptical galaxies near enough to allow the study of their stellar populations directly. Most information on the stellar populations of elliptical galaxies rely on the interpretation of integrated light. However, direct information on the bright stellar content of low-luminosity elliptical galaxies can be obtained from a study of the Local Group dwarf ellipticals. The nearby Andromeda galaxy, M31 has four low-luminosity elliptical companions: M32, NGC 205, NGC 185 and NGC 147, the subjects of this review.
This review will begin with a broad summary of population characteristics of dwarf elliptical galaxies (dE's), it will briefly summarize what is known about the stellar populations of the four Andromeda companions, and then discuss the specific case of M32 in detail. M32, the highest surface brightness Andromeda companion, has characteristics very simliar to the giant ellipticals, and has therefore been the focus of much of the controversy surrounding the issue of the ages of elliptical galaxies. Studies of its integrated light, in combination with new studies of its brightest resolved giants, particularly in the near-infrared, may help to resolve many of the outstanding questions regarding the stellar populations in elliptical galaxies.