Asteroseismic signatures of the helium core flash
| Autor: | M. M. Miller Bertolami, Alejandro H. Córsico, Tiara Battich, Jørgen Christensen-Dalsgaard, Leandro Gabriel Althaus |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2020 |
| Předmět: |
Physics
Solar mass 010504 meteorology & atmospheric sciences FOS: Physical sciences chemistry.chemical_element Astronomy and Astrophysics Astrophysics Astrophysics::Cosmology and Extragalactic Astrophysics Giant star 01 natural sciences Subdwarf Exoplanet Photometry (optics) Flash (photography) Stars chemistry Astrophysics - Solar and Stellar Astrophysics 0103 physical sciences Astrophysics::Solar and Stellar Astrophysics Astrophysics::Earth and Planetary Astrophysics 010303 astronomy & astrophysics Solar and Stellar Astrophysics (astro-ph.SR) Helium Astrophysics::Galaxy Astrophysics 0105 earth and related environmental sciences |
| Zdroj: | Miller Bertolami, M M, Battich, T, Córsico, A H, Christensen-Dalsgaard, J & Althaus, L G 2020, ' Asteroseismic signatures of the helium core flash ', Nature Astronomy, vol. 4, no. 1, pp. 67-71 . https://doi.org/10.1038/s41550-019-0890-0 |
| DOI: | 10.1038/s41550-019-0890-0 |
| Popis: | All evolved stars with masses $M_\star\lesssim 2M_\odot$ undergo a helium(He)-core flash at the end of their first stage as a giant star. Although theoretically predicted more than 50 years ago, this core-flash phase has yet to be observationally probed. We show here that gravity modes (g modes) stochastically excited by He-flash driven convection are able to reach the stellar surface, and induce periodic photometric variabilities in hot-subdwarf stars with amplitudes of the order of a few mmag. As such they can now be detected by space-based photometry with the Transiting Exoplanet Survey Satellite (TESS) in relatively bright stars (e.g. magnitudes $I_C\lesssim 13$). The range of predicted periods spans from a few thousand seconds to tens of thousand seconds, depending on the details of the excitation region. In addition, we find that stochastically excited pulsations reproduce the pulsations observed in a couple of He-rich hot subdwarf stars. These stars, and in particular the future TESS target Feige 46, are the most promising candidates to probe the He-core flash for the first time. 14 Figures including Supplementary Information. Letter to Nature Astronomy |
| Databáze: | OpenAIRE |
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