Journal article
RECONCILING THE GALACTIC BULGE TURNOFF AGE DISCREPANCY WITH ENHANCED HELIUM ENRICHMENT
Astrophysical journal. Letters, Vol.751(2), pp.1-6
06/01/2012
DOI: 10.1088/2041-8205/751/2/L39
Abstract
We show that the factor similar to 2 discrepancy between spectroscopic and photometric age determinations of the Galactic bulge main-sequence turnoff can be naturally explained by positing an elevated helium enrichment for the bulge relative to that assumed by standard isochrones. Helium enhancement relative to standard isochrones is confirmed at the 2.3 sigma level. We obtain an upper bound on the helium enrichment for the metal-rich ([Fe/H] approximate to +0.30) stars of Delta Y approximate to +0.11 relative to canonical expectations, given the requirement that the spectroscopic and photometric ages be consistent and the limiting condition of instantaneous star formation. We discuss phenomenological evidence that the bulge may have had a chemical evolution that is distinct from the solar neighborhood in this manner, and we make several testable predictions. Should this emerging picture of the bulge as helium-enhanced hold, it will require the development of new isochrones, new model atmospheres, and modified analysis and cosmological interpretation of the integrated light of other bulges and elliptical galaxies.
Details
- Title: Subtitle
- RECONCILING THE GALACTIC BULGE TURNOFF AGE DISCREPANCY WITH ENHANCED HELIUM ENRICHMENT
- Creators
- David M. Nataf - The Ohio State UniversityAndrew P. Gould - The Ohio State University
- Resource Type
- Journal article
- Publication Details
- Astrophysical journal. Letters, Vol.751(2), pp.1-6
- Publisher
- Iop Publishing Ltd
- DOI
- 10.1088/2041-8205/751/2/L39
- ISSN
- 2041-8205
- eISSN
- 2041-8213
- Number of pages
- 6
- Grant note
- AST-1103471 / NSF; National Science Foundation (NSF) PGSD3-403304-2011 / NSERC; Natural Sciences and Engineering Research Council of Canada (NSERC) 1103471 / Division Of Astronomical Sciences; National Science Foundation (NSF); NSF - Directorate for Mathematical & Physical Sciences (MPS)
- Language
- English
- Date published
- 06/01/2012
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9984701828702771
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