The elusive nature of the R stars

Dominguez, I. and Piersanti, L. and Cabezon, R. and Zamora, O. and Garcia-Senz, D. and Abia, C. and Straniero, O.. (2010) The elusive nature of the R stars. Memorie della Societa Astronomica Italiana, 81. p. 1039.

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R stars are carbon stars, less luminous and hotter than the carbon stars evolving along the AGB phase. Thus, their carbon enrichment cannot be a consequence of the third dredge-up, a fact also in agreement with the lack of s-element enhancements in their envelopes. Since their discovery the absence of binaries has lead to the conclusion that a previous merger might play a fundamental role in the observed chemical composition, likely through non-standard mixing at the time of the He-flash. On the other hand numerical simulations, in which the He-flash is artificially located close to the edge of a degenerate He core, have successfully induced mixing of carbon into the envelope. In this context it has been suggested that the merger of a degenerate He core with that of a normal red giant star could lead to the formation of a rapidly rotating core undergoing off-centre He ignition in highly degenerate conditions. This scenario is also supported by statistical analysis of the potential mergers that could explain the number, and location in the Galaxy, of observed R stars. Basing on detailed stellar models we will show the evolution of these mergers, that are very common in nature, and do not seem to be the progenitors of (hot) R stars.
Faculties and Departments:05 Faculty of Science > Departement Physik > Former Organization Units Physics > Theoretische Physik Astrophysik (Thielemann)
10 Zentrale universitäre Einrichtungen > sciCORE
UniBasel Contributors:Cabezon, Ruben M.
Item Type:Article, refereed
Article Subtype:Research Article
Note:Publication type according to Uni Basel Research Database: Journal article
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Last Modified:16 Oct 2019 15:18
Deposited On:16 Oct 2019 15:18

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