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Published January 2007 | Accepted Version + Published
Journal Article Open

Integrated-light Two Micron All Sky Survey infrared photometry of Galactic globular clusters


We have mosaicked Two Micron All Sky Survey (2MASS) images to derive surface brightness profiles in J, H, and K_s for 104 Galactic globular clusters. We fit these with King profiles and show that the core radii are identical to within the errors for each of these IR colors and are identical to the core radii at V in essentially all cases. We derive integrated-light colors V-J, V-H, V-K_s, J-H, and J-Ks for these globular clusters. Each color shows a reasonably tight relation between the dereddened colors and metallicity. Fits to these are given for each color. The IR-IR colors have very small errors, due largely to the all-sky photometric calibration of the 2MASS survey, while the V-IR colors have substantially larger uncertainties. We find fairly good agreement with measurements of integrated-light colors for a smaller sample of Galactic globular clusters by M. Aaronson, M. Malkan, and D. Kleinmann from 1977. Our results provide a calibration for the integrated light of distant single-burst old stellar populations from very low to solar metallicities. A comparison of our dereddened measured colors with predictions from several models of the integrated light of single-burst old populations shows good agreement in the low-metallicity domain for V-K_s colors but also shows an offset at a fixed [Fe/H] of ~0.1 mag in J-K_s, which we ascribe to photometric system transformation issues. Some of the models fail to reproduce the behavior of the integrated-light colors of the Galactic globular clusters near solar metallicity.

Additional Information

© 2007. The American Astronomical Society. Print publication: Issue 1 (2007 January) Received 2006 June 10, accepted for publication 2006 August 12. Published 2006 December 4. This publication makes use of data products from the Two Micron All Sky Survey, which is a joint project of the University of Massachusetts and Infrared Processing and Analysis Center, California Institute of Technology, funded by NASA and the NSF. We thank John Carpenter and Pat Côté , who participated in the initial phase of this work. J. G. C. is grateful to NSF grant AST 05-07219 for partial support. S. H. was supported by a Summer Undergraduate Research Fellowship, provided in part through an NSF grant to J. G. C., AST 02-05951. Support for S. A. M. was provided by NASA through the Spitzer Fellowship Program under award 1273192. S. G. D. acknowledges partial support from the Ajax Foundation.

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Published - COHaj07.pdf

Accepted Version - 0609353.pdf


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