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Record 56 of 1773
Constraints on the formation history of the elliptical galaxy NGC 3923 from the colors of its globular clusters
External Online Source: doi:10.1086/175549
Author and Affiliation:
Zepf, Stephen E.(University of California, Berkeley, CA, United States)
Ashman, Keith M.(University of Kansas, Lawrence, KS, United States)
Geisler, Doug(Cerro Tololo Inter-American Observatory, La Serena, Chile)
Abstract: We present a study of the colors of globular clusters associated with the elliptical galaxy NGC 3923. Our final sample consists of Wasington system C and T(sub 1) photometry for 143 globular cluster candidates with an expected contamination of no more than 10%. We find that the color distribution of the NGC 3923 globular cluster system (GCS) is broad and appears to have at least two peaks. A mixture modeling analysis of the color distribution indicates that a two-component model is favored over a single-component one at a high level of confidence (greater than 99%). This evidence for more than one population in the GCS of NGC 3923 is similar to that previously noted for the four other elliptical galaxies for which similar data have been published. Furthermore, we find that the NGC 3923 GCS is redder than the GCSs of previously studed elliptical galaxies of similar luminosity. The median metallicity inferred from our (C-(T(sub 1)))(sub 0) colors is (Fe/H)(sub med) = -0.56, with an uncertainty of 0.14 dex arising from all sources of uncertainty in the mean color. This is more metal rich than the median metallicity found for the GCS of M87 using the same method, (Fe/H)(sub med) = -0.94. Since M87 is more luminous than NGC 3923, this result points to significant scatter about any trend of higher GCS metallicity with increasing galaxy luminosity. We also show that there is a color gradient in the NGC 3923 GCS corresponding to about -0.5 dex in Delta(Fe/H)/Delta(log r). We conclude that the shape of the color distribution of individual GCSs and the variation in mean color among the GCSs of ellipticals are difficult to understand if elliptical galaxies are formed in a single protogalactic collapse. Models in which ellipticals and their globular clusters are formed in more than one event, such as a merger scenario, are more successful in accounting for these observations.
Publication Date: Apr 20, 1995
Document ID:
(Acquired Dec 28, 1995)
Accession Number: 95A86207
Subject Category: ASTROPHYSICS
Document Type: Journal Article
Publication Information: Astrophysical Journal, Part 1 (ISSN 0004-637X); 443; 2; p. 570-577
Publisher Information: United States
Contract/Grant/Task Num: NAS5-26555
Financial Sponsor: NASA; United States
Organization Source: NASA Goddard Space Flight Center; Greenbelt, MD, United States
Description: 8p; In English
Distribution Limits: Unclassified; Publicly available; Unlimited
Rights: Copyright
Imprint And Other Notes: Astrophysical Journal, Part 1 vol. 443, no. 2 p. 570-577 April 20, 1995
Miscellaneous Notes: Research sponsored by the Fund for Astrophysical Research
Availability Source: Other Sources
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