Clues to the Metallicity Distribution in the Galactic Bulge: Abundances in OGLE-2007-BLG-349S
Abstract
We present an abundance analysis based on high-dispersion and high signal-to-noise ratio Keck spectra of a very highly microlensed Galactic bulge dwarf, OGLE-2007-BLG-349S, with T_(eff) ~ 5400 K. The amplification at the time the spectra were taken ranged from 350 to 450. This bulge star is highly enhanced in metallicity with [Fe/H ] = + 0.51 ± 0.09 dex. The abundance ratios for the 28 species of 26 elements for which features could be detected in the spectra are almost all solar. In particular, there is no evidence for enhancement of any of the α-elements, including O and Mg. We conclude that the high [Fe/H] seen in this star, when combined with the equally high [Fe/H] derived in previous detailed abundance analysis of two other Galactic bulge dwarfs, both also highly magnified by microlensing, implies that the median metallicity in the Galactic bulge is very high. We thus infer that many previous estimates of the metallicity distribution in the Galactic bulge have substantially underestimated the mean Fe metallicity there due to sample bias, and suggest a candidate mechanism for such. If our conjecture proves valid, it may be necessary to update the calibrations for the algorithms used by many groups to interpret spectra and broadband photometry of the integrated light of very metal-rich old stellar populations, including luminous elliptical galaxies.
Additional Information
© 2008 The American Astronomical Society. Received 2008 January 21; accepted 2008 April 7. Based in part on observations obtained at the W. M. Keck Observatory, which is operated jointly by the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. We are grateful to the many people who have worked to make the Keck Telescope and HIRES a reality and to operate and maintain the Keck Observatory. The authors wish to extend special thanks to those of Hawaiian ancestry on whose sacred mountain we are privileged to be guests. Without their generous hospitality, none of the observations presented herein would have been possible. J. G. C. and W. H. are grateful to NSF grant AST-0507219 to J. G. C. for partial support. Work by A. G. was supported by NSF grant AST-042758. The OGLE project is partially supported by the Polish MNiSW grant N20303032/4275.We thank Manuela Zoccali for providing results in advance of publication on the metallicity distribution function of bulge giants.Attached Files
Published - Cohen_2008_ApJ_682_1029.pdf
Accepted Version - 0801.3264.pdf
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Additional details
- Eprint ID
- 96043
- Resolver ID
- CaltechAUTHORS:20190603-134859287
- AST-0507219
- NSF
- AST-042758
- NSF
- N20303032/4275
- Ministerstwo Nauki i Szkolnictwa Wyższego (MNiSW)
- Created
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2019-06-03Created from EPrint's datestamp field
- Updated
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2021-11-16Created from EPrint's last_modified field