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

被引:19
作者
Davidge, TJ
Rigaut, F
Chun, M
Brandner, W
Potter, D
Northcott, M
Graves, JE
机构
[1] Natl Res Council Canada, Herzberg Inst Astrophys, Canadian Gemini Off, Victoria, BC V9E 2E7, Canada
[2] Gemini Observ, Hilo, HI 96720 USA
[3] Univ Hawaii, Inst Astron, Honolulu, HI 96822 USA
基金
澳大利亚研究理事会; 美国国家科学基金会;
关键词
galaxies : evolution; galaxies : individual (M32); galaxies : stellar content; stars : AGB and post-AGB;
D O I
10.1086/317887
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
The bright stellar content near the center of the Local Group elliptical galaxy M32 is investigated with 0".12 FWHM H and K images obtained with the Gemini Mauna Kea telescope. Stars with K = 15.5, which are likely evolving near 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. Moreover, the projected density of bright AGB stars follows the visible light profile to within 2" of the nucleus, indicating that the brightest stars are well mixed throughout the galaxy. Thus, there is no evidence for an age gradient, and the radial variations in spectroscopic indices and ultraviolet 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 formation or they originated in a separate system that merged with M32.
引用
收藏
页码:L89 / L92
页数:4
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