Pulsation in extremely low-mass helium stars

C. S. Jeffery, Hideyuki Saio

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

Abstract

We explore the stability of extremely low-mass stars (M < 0.25 M⊙ across a wide range of composition, effective temperature, and luminosity. We identify the instability boundaries associated with radial oscillations. These are a strong function of both composition and radial order (0 ≤ n ≤ 13). The classical blue edge shifts to higher effective temperature and luminosity with decreasing hydrogen abundance. Higher-order modes are more easily excited, and small islands of instability develop. Short-period oscillations have been discovered in the low-mass pre-white dwarf component of the eclipsing binary J0247-25. If its envelope is depleted in hydrogen, J0247-25B is unstable to intermediate-order p modes. Driving is by the classical κ mechanism operating in the second helium ionization zone. The observed periods, temperature and luminosity of J0247-25B require an envelope hydrogen abundance 0.2 ≤ X ≤ 0.3.

Original languageEnglish
Title of host publicationPrecision Asteroseismology
EditorsJoyce Guzik, William Chaplin, William Chaplin, Gerald Handler, Andrzej Pigulski
Pages425-426
Number of pages2
EditionS301
DOIs
Publication statusPublished - 2014 Mar 3

Publication series

NameProceedings of the International Astronomical Union
NumberS301
Volume9
ISSN (Print)1743-9213
ISSN (Electronic)1743-9221

Keywords

  • stars: early-type
  • stars: interiors
  • stars: oscillations
  • subdwarfs
  • white dwarfs

ASJC Scopus subject areas

  • Astronomy and Astrophysics

Fingerprint Dive into the research topics of 'Pulsation in extremely low-mass helium stars'. Together they form a unique fingerprint.

Cite this