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EDP Sciences, Astronomy & Astrophysics, (638), p. A30, 2020

DOI: 10.1051/0004-6361/202037743

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On the formation of hydrogen-deficient low-mass white dwarfs

Journal article published in 2020 by Tiara Battich ORCID, Leandro G. Althaus, Alejandro H. Córsico ORCID
This paper is made freely available by the publisher.
This paper is made freely available by the publisher.

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Abstract

Context. Two of the possible channels for the formation of low-mass (M ≲ 0.5 M) hydrogen-deficient white dwarfs are the occurrence of a very-late thermal pulse after the asymptotic giant-branch phase or a late helium-flash onset in an almost stripped core of a red giant star. Aims. We aim to asses the potential of asteroseismology to distinguish between the hot flasher and the very-late thermal pulse scenarios for the formation of low-mass hydrogen-deficient white dwarfs. Methods. We computed the evolution of low-mass hydrogen-deficient white dwarfs from the zero-age main sequence in the context of the two evolutionary scenarios. We explore the pulsation properties of the resulting models for effective temperatures characterizing the instability strip of pulsating helium-rich white dwarfs. Results. We find that there are significant differences in the periods and in the period spacings associated with low radial-order (k ≲ 10) gravity modes for white-dwarf models evolving within the instability strip of the hydrogen-deficient white dwarfs. Conclusions. The measurement of the period spacings for pulsation modes with periods shorter than ∼500 s may be used to distinguish between the two scenarios. Moreover, period-to-period asteroseismic fits of low-mass pulsating hydrogen-deficient white dwarfs can help to determine their evolutionary history.