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J/AJ/106/493              Globular clusters in M87                  (Lee+, 1993)

Metal abundances for a large sample of globular clusters in M87 LEE M.G., GEISLER D. <Astron. J. 106, 493 (1993)> =1993AJ....106..493L (SIMBAD/NED Reference)
ADC_Keywords: Galaxies, optical; Clusters, globular; Photometry, CMT1T2V Abstract: We present deep integrated Washington CCD photometry of the extremely populous globular cluster system of NGC 4486 (M87) in Virgo. The metallicities of 407 of the best candidates with T1 < 22 have been estimated from the (C-T1) color. These values are internally precise to ∼0.15dex and accurate to ∼0.25dex. The mean metallicity of the globular clusters is [Fe/H] = -0.86dex, with a formal standard error of the mean of 0.03dex but a more realistic uncertainty of about 0.2dex. This value is higher than that of the corresponding means of the globular clusters in the Galaxy and M31, but similar to those of the globular clusters in NGC 1399 and NGC 5128, as expected from the relative parent galaxy luminosities. Approximately 10% of the clusters exceed solar abundance, similar to the case for the globular clusters in NGC 1399 and NGC 5128. As found by Couture et al. [ApJS, 73, 671 (1990)], there is a large metallicity dispersion at any radius, with a sigma ∼ 0.65dex. However, in contrast to their result and that of previous small-field CCD studies, the globular clusters display a marked gradient in both mean (M-T1) and (C-T1) color with galactocentric distance. The mean metallicity decreases by some 0.6dex over the radial extent of the cluster sample. This result is consistent with the early photographic study by Strom et al. [ApJ, 245, 416 (1981)]. The metallicity distribution function is remarkably similar to that of NGC 1399 found by Ostrov et al. [AJ, 105, 1762 (1993)] using the same technique. The two central cluster ellipticals show significant peaks at very similar metallicities, indicating similar formation and enrichment histories. We also find that this structure in the metallicity distribution function persists to radii where the halo light is dominated by the cD envelope. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table3 68 144 M87 globular cluster candidates with T1 < 21
Byte-by-byte Description of file: table3
Bytes Format Units Label Explanations
1- 2 A2 --- Field Field designator: N1 = North, E1 = East-1, E2 = East-2, W1 = West, and C = Center. 4- 6 I3 --- ID Running number (finding charts are given in Plates 15-19 in the printed paper. 9- 13 F5.1 pix X X coordinate of object 16- 20 F5.1 pix Y Y coordinate of object 23- 27 F5.2 mag T1 T1 magnitude (Washington system) 29- 32 F4.2 mag e_T1 rms uncertainty on T1 35- 38 F4.2 mag M-T1 M-T1 color (Washington system) 40- 43 F4.2 mag e_M-T1 rms uncertainty on M-T1 46- 49 F4.2 mag C-T1 C-T1 color (Washington system) 51- 54 F4.2 mag e_C-T1 rms uncertainty on C-T1 57- 61 F5.2 --- [Fe/H] Derived metal abundance, [Fe/H] 64- 68 F5.1 arcsec RG Projected galactocentric distance
Origin: AAS CD-ROM series, Volume 1, 1993
(End) Patricia Bauer [CDS] 20-Sep-1994
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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