THE SPATIAL STRUCTURE OF THE M87 GLOBULAR-CLUSTER SYSTEM

被引:130
作者
MCLAUGHLIN, DE
HARRIS, WE
HANES, DA
机构
[1] QUEENS UNIV,DEPT PHYS,KINGSTON K7L 3N6,ONTARIO,CANADA
[2] KITT PEAK NATL OBSERV,TUCSON,AZ 85726
关键词
GALAXIES; ELLIPTIC AND LENTICULAR; CD; INDIVIDUAL; (M87); GLOBULAR CLUSTERS; GENERAL;
D O I
10.1086/173744
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
Wide-field (approximately 14' x 14') CCD photometry in V of a field centered on M87 = NGC 4486 is used to examine the spatial structure, luminosity function, and specific frequency of the galaxy's globular cluster system (GCS). The salient results are as follows: (1) As recently reported by McLaughlin et al., the radial profile of the GCS shows an excess component which coincides in position and size with the cD envelope of the galaxy's halo. (2) In projection, the GCS of M87 is definitely elliptical in shape, with a major axis position angle which roughly coincides with that of the galaxy isophotes. However, its ellipticity increases with galactocentric radius faster than does the ellipticity of the underlying halo light. (3) The luminosity function of the GCS is well described by a Gaussian of dispersion sigma = 1.73, and peak magnitude V0 = 24.2. We confirm earlier claims that the bright half of the luminosity function shows no significant variation with galactocentric radius, out to R congruent-to 6.8'. (4) We have computed the run of the ratio of globular cluster numbers to halo luminosity (specific frequency) over the region 1.2' less than or similar to R less than or similar to 9.1'; we find that the net specific frequency of M87, for (m - M)V(Virgo) = 31.0 +/- 0.2, is S(N) = 14 +/- 4, which is almost three times greater than for other, more normal Virgo ellipticals. A brief discussion of this high-S, phenomenon is given, and we expand on the conclusion of McLaughlin et al. that the high S(N) of the M87 cD envelope implies that this structure was accreted while still gaseous.
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收藏
页码:486 / 507
页数:22
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