Journal article
The Controversial Star-Formation History and Helium Enrichment of the Milky Way Bulge
Publications of the Astronomical Society of Australia, Vol.33, 023
2016
DOI: 10.1017/pasa.2015.38
Abstract
The stellar population of the Milky Way bulge is thoroughly studied, with a plethora of measurements from virtually the full suite of instruments available to astronomers. It is thus perhaps surprising that alongside well-established results lies some substantial uncertainty in its star-formation history. Cosmological models predict the bulge to host the Galaxy's oldest stars for [Fe/H]less than or similar to-1, and this is demonstrated by RR Lyrae stars and globular cluster observations. There is consensus that bulge stars with [Fe/H]less than or similar to 0 are older than t approximate to 10 Gyr. However, at super-solar metallicity, there is a substantial unresolved discrepancy. Data from spectroscopic measurements of the main-sequence turnoff and subgiant branch, the abundances of asymptotic giant branch stars, the period distribution of Mira variables, the chemistry and central-star masses of planetary nebulae, all suggest a substantial intermediate-age population (t approximate to 3 Gyr). This is in conflict with predictions from cosmologically motivated chemical evolution models and photometric studies of the main-sequence turnoff region, which both suggest virtually no stars younger than t approximate to 8 Gyr. A possible resolution to this conflict is enhanced helium-enrichment, as this would shift nearly all of the age estimates in the direction of decreasing discrepancy.
Details
- Title: Subtitle
- The Controversial Star-Formation History and Helium Enrichment of the Milky Way Bulge
- Creators
- David M. Nataf - Australian National University
- Resource Type
- Journal article
- Publication Details
- Publications of the Astronomical Society of Australia, Vol.33, 023
- Publisher
- Cambridge Univ Press
- DOI
- 10.1017/pasa.2015.38
- ISSN
- 1323-3580
- eISSN
- 1448-6083
- Number of pages
- 7
- Grant note
- FL110100012 / Australian Research Council grant; Australian Research Council
- Language
- English
- Date published
- 2016
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9984701825202771
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