The effect of enhanced helium abundances on the AGB-supernove mass transition

Amanda I. Karakas, Luke J. Shingles

Research output: Chapter in Book/Report/Conference proceedingConference PaperResearch

1 Citation (Scopus)


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 languageEnglish
Title of host publicationMemorie della Societa Astronomica Italiana
Subtitle of host publication2017 AGB-Supernovae Mass Transition; Monte Porzio Catone; Italy; 27 March 2017 through 31 March 2017
EditorsA Karakas, P Ventura, F Dell'Agli, M Di Criscienzo
Place of PublicationItaly
PublisherFabrizio Serra Editore
Number of pages4
Publication statusPublished - 2017
EventThe AGB-Supernovae Mass Transition 2017 - Observatory of Rome, Monte Porzio Catone, Italy
Duration: 27 Mar 201731 Mar 2017

Publication series

NameSocieta Astronomica Italiana. Memorie
PublisherFabrizio Serra Editore
ISSN (Print)0037-8720


ConferenceThe AGB-Supernovae Mass Transition 2017
CityMonte Porzio Catone
OtherLittle 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


  • Galaxy: abundances, nucleosynthesis, abundances
  • ISM: abundances
  • Stars: abundances, stars: AGB and post-AGB

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