The peak brightness and spatial distribution of asymptotic giant branch stars near the nucleus of M32

Citation
Tj. Davidge et al., The peak brightness and spatial distribution of asymptotic giant branch stars near the nucleus of M32, ASTROPHYS J, 545(2), 2000, pp. L89-L92
Citations number
37
Categorie Soggetti
Space Sciences
Journal title
ASTROPHYSICAL JOURNAL
ISSN journal
0004637X → ACNP
Volume
545
Issue
2
Year of publication
2000
Part
2
Pages
L89 - L92
Database
ISI
SICI code
0004-637X(200012)545:2<L89:TPBASD>2.0.ZU;2-B
Abstract
The bright stellar content near the center of the Local Group elliptical ga laxy M32 is investigated with 0".12 FWHM H and K images obtained with the G emini Mauna Kea telescope. Stars with K = 15.5, which are likely evolving n ear the tip of the asymptotic giant branch (AGB), are resolved to within 2" of the nucleus, and it is concluded that the peak stellar brightness near the center of M32 is similar to that in the outer regions of the galaxy. Mo reover, the projected density of bright AGB stars follows the visible light profile to within 2" of the nucleus, indicating that the brightest stars a re well mixed throughout the galaxy. Thus, there is no evidence for an age gradient, and the radial variations in spectroscopic indices and ultraviole t colors that have been detected previously must be due to metallicity and/ or some other parameter. We suggest that either the bright AGB stars formed as part of a highly uniform and coherent galaxy-wide episode of star forma tion or they originated in a separate system that merged with M32.