Vol. 585
In section 7. Stellar structure and evolution

Pulsating low-mass white dwarfs in the frame of new evolutionary sequences. II. Nonadiabatic analysis

by A.H. Corsico, L. G. Althaus A&A 585, A1


Pulsating low-mass (M⋆/M⊙ 0.45) white dwarfs, including he so-called extremely low-mass white dwarfs (M⋆/M⊙ 0.18−0.20), are being currently discovered in the Galaxy through dedicated photomeric surveys. The authors present a detailed nonadiabatic pulsational analysis of low-mass white dwarfs and provide a detailed description of the pulsation stability properties of variable low-mass white dwarfs during the terminal cooling branch. They find that a dense spectrum of unstable radial modes and nonradial g and p modes are driven by the κ − γ mechanism because of the partial ionization of H in the stellar envelope.Also, low-order, unstable g modes characterized by short pulsation periods are excited by H burning via the ε mechanism. They compare their results with the excited modes observed in the seven known variable low-mass white dwarfs and find good agreement.