Metallicities on the Double Main Sequence of ω Centauri Imply Large Helium Enhancement
Open accessAbstract
Having shown in a recent paper that the main sequence of ω Centauri is split into two distinct branches, we now present spectroscopic results showing that the bluer sequence is less metal-poor. We have carefully combined VLT's GIRAFFE spectra of 17 stars on each side of the split into a single spectrum for each branch, with adequate signal-to-noise ratio, to show clearly that the stars of the blue main sequence are less metal-poor by 0.3 dex than those of the dominant red one. From an analysis of the individual spectra, we could not detect any abundance spread among the blue main-sequence stars, whereas the red main-sequence stars show a 0.2 dex spread in metallicity. We use stellar structure models to show that only greatly enhanced helium can explain the color difference between the two main sequences, and we discuss ways in which this enhancement could have arisen.
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The huge increase in He is one of the reasons why intermediate-mass AGB stars have been implicated in the origin of the multiple populations observed in Galactic GCs.
“This huge increase in He is one of the reasons why intermediate-mass AGB stars have been implicated in the origin of the multiple populations observed in Galactic GCs (D'Antona et al. 2002; Norris 2004; Piotto et al. 2005).”
From The Dawes Review 2: Nucleosynthesis and Stellar Yields of Low- and Intermediate-Mass Single Stars (2014) · cites this paper as Piotto et al. 2005
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The Dawes Review 2: Nucleosynthesis and Stellar Yields of Low- and Intermediate-Mass Single Stars
Karakas, A. I., & Lattanzio, J. C. (2014) · Publications of the Astronomical Society of Australia · doi:10.1017/pasa.2014.21 · Cited by 735 · see citing works
“This huge increase in He is one of the reasons why intermediate-mass AGB stars have been implicated in the origin of the multiple populations observed in Galactic GCs (D’Antona et al. 2002; Norris 2004; Piotto et al. 2005).”
Background
- Authors
- Piotto, G., Villanova, S., Bedin, L. R., Gratton, R., Cassisi, S., Momany, Y., Recio‐Blanco, A., Lucatello, S., Anderson, J., King, I. R., Pietrinferni, A., & Carraro, G.
- Affiliations
- University of Padua (IT)
- European Southern Observatory (DE)
- Osservatorio Astronomico di Padova (IT)
- Collurania Teramo Observatory (IT)
- Rice University (US)
- University of Washington (US)
- ORCID
- Venue
- The Astrophysical Journal
- Publisher
- American Astronomical Society
- Published
- 2005-03-10
- Volume
- 621
- Issue
- 2
- Pages
- 777-784
- ISSN
- 0004-637X (ISSN-L)
- 1538-4357
- OpenAlex
- W2090505598
- Cited by
- 446
- References
- 0
- Citations by year
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- FWCI
- 20.15
- Type
- journal article
- Language
- en
- Open access
- bronze
- doi.org
- Locations
- The Astrophysical Journal (publishedVersion)
- arXiv (Cornell University) (submittedVersion)
- HAL (submittedVersion)
- CERN Document Server (European Organization for Nuclear Research) (submittedVersion)
- Padua Research Archive (University of Padova) (submittedVersion, other-oa)
- arXiv (Cornell University)
- Funders
- Space Telescope Science Institute
- Ministero dell’Istruzione, dell’Università e della Ricerca
- Topics
- Physical Sciences › Physics and Astronomy › Astronomy and Astrophysics › Stellar, planetary, and galactic studies
- Physical Sciences › Physics and Astronomy › Astronomy and Astrophysics › Galaxies: Formation, Evolution, Phenomena
- Physical Sciences › Physics and Astronomy › Instrumentation › Astronomy and Astrophysical Research
- Keywords
- Omega Centauri, helium enrichment, metallicity, stellar structure models, globular cluster stars
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