Abstract
Globular clusters are now known to harbour helium-rich stellar populations. While the stars we see today are all of low mass, there were once stars of all mass ranges with helium mass fractions up to Y ≈ 0.40. It has also been suggested that the younger stellar component of the Galactic bulge is both metal-rich and helium rich, with Y up to 0.40. In this study we investigate the effect of helium enrichment on the stellar evolution of stars near the AGB-supernova mass transition, which is 8 Msun for solar metallicity. In particular we show that the AGB-supernova mass transition decreases in mass with increasing helium abundance, for both metal-poor and metal-rich models. This will have an impact on the stellar yields and on the chemical evolution of helium rich stellar populations.
| Original language | English |
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| Title of host publication | Memorie della Societa Astronomica Italiana |
| Subtitle of host publication | 2017 AGB-Supernovae Mass Transition; Monte Porzio Catone; Italy; 27 March 2017 through 31 March 2017 |
| Editors | A Karakas, P Ventura, F Dell'Agli, M Di Criscienzo |
| Place of Publication | Italy |
| Publisher | Fabrizio Serra Editore |
| Pages | 244-247 |
| Number of pages | 4 |
| Volume | 88 |
| Edition | 3 |
| Publication status | Published - 2017 |
| Event | The AGB-Supernovae Mass Transition 2017 - Observatory of Rome, Monte Porzio Catone, Italy Duration: 27 Mar 2017 → 31 Mar 2017 https://web.archive.org/web/20170111030144/http://agb-supernovae.weebly.com:80/ https://agb-supernovae.weebly.com/ |
Publication series
| Name | Societa Astronomica Italiana. Memorie |
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| Publisher | Fabrizio Serra Editore |
| ISSN (Print) | 0037-8720 |
Conference
| Conference | The AGB-Supernovae Mass Transition 2017 |
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| Country/Territory | Italy |
| City | Monte Porzio Catone |
| Period | 27/03/17 → 31/03/17 |
| Other | Little is known about stars in the mass range between those that end their lives as white dwarfs and those that die in spectacular supernova explosions. The uncertainty stems from the fact that stars in this transition mass range from about ~7 to 11 solar masses are both difficult to model theoretically and there are few observational clues as to their evolutionary history. Following the ignition of carbon in the core under conditions of partial degeneracy, the stars then continue to evolve through the asymptotic giant branch (AGB) phase and are known as super-AGB stars. Super-AGB stars have oxygen-neon degenerate cores as opposed to the carbon-oxygen cores of their lower mass counterparts. The final fate of single super-AGB stars depends on the rate of mass loss from the surface: if the core can grow big enough to reach the Chandrasekhar mass then it will explode as an electron capture supernova. |
| Internet address |
Keywords
- Galaxy: abundances, nucleosynthesis, abundances
- ISM: abundances
- Stars: abundances, stars: AGB and post-AGB