Meléndez, Jorge and Cohen, Judith G. (2007) Magnesium Isotopes in Metal-poor Dwarfs: The Rise of AGB Stars and the Formation Timescale of the Galactic Halo. Astrophysical Journal Letters, 659 (1). L25-L28. ISSN 2041-8205. doi:10.1086/516735. https://resolver.caltech.edu/CaltechAUTHORS:20100223-132200164
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Abstract
We have determined magnesium isotopic ratios (^(25, 26)Mg/Mg) in metal-poor (-2.6 ≤ [Fe/H] ≤ -1.3) halo dwarfs employing high signal-to-noise ratio (S/N = 90-280), high spectral resolution (R = 10^5) Keck High Resolution Echelle Spectrometer (HIRES) spectra. Unlike previous claims of an important contribution from intermediate-mass asymptotic giant branch (AGB) stars at low metallicities, we find that the rise of the AGB contribution in the Galactic halo did not occur until intermediate metallicities ([Fe/H] ≳ -1.5).
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| Additional Information: | © 2007 The American Astronomical Society. Received 2007 January 24; accepted 2007 February 26; published 2007 March 9. J. M. thanks C. Chiappini for useful discussions and D. Yong for providing data to check our MgH line list as well as for useful discussions on Mg isotopic ratios. J. G. C. is grateful for partial support from NSF grant AST-0507219. We have made use of data from the SIMBAD database operated at CDS. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Mauna Kea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. | |||||||||
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| Subject Keywords: | galaxy : halo; stars : abundances; stars : AGB and post-AGB; stars : atmospheres; stars : Population II | |||||||||
| Issue or Number: | 1 | |||||||||
| DOI: | 10.1086/516735 | |||||||||
| Record Number: | CaltechAUTHORS:20100223-132200164 | |||||||||
| Persistent URL: | https://resolver.caltech.edu/CaltechAUTHORS:20100223-132200164 | |||||||||
| Official Citation: | Magnesium Isotopes in Metal-poor Dwarfs: The Rise of AGB Stars and the Formation Timescale of the Galactic Halo Jorge Meléndez and Judith G. Cohen 2007 ApJ 659 L25-L28 doi: 10.1086/516735 | |||||||||
| Usage Policy: | No commercial reproduction, distribution, display or performance rights in this work are provided. | |||||||||
| ID Code: | 17566 | |||||||||
| Collection: | CaltechAUTHORS | |||||||||
| Deposited By: | Tony Diaz | |||||||||
| Deposited On: | 02 Mar 2010 17:46 | |||||||||
| Last Modified: | 08 Nov 2021 23:36 |
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