EDP Sciences
Free access
Volume 440, Number 1, September II 2005
Page(s) L1 - L4
Section Letters
DOI http://dx.doi.org/10.1051/0004-6361:200500159

A&A 440, L1-L4 (2005)
DOI: 10.1051/0004-6361:200500159


The formation of DA white dwarfs with thin hydrogen envelopes

L. G. Althaus1, M. M. Miller Bertolami2, A. H. Córsico2, 3, E. García-Berro1, 4 and P. Gil-Pons1

1  Departament de Física Aplicada, Universitat Politècnica de Catalunya, Av. del Canal Olímpic s/n, 08860 Castelldefels, Barcelona, Spain
    e-mail: althaus@fcaglp.unlp.edu.ar
2  Facultad de Ciencias Astronómicas y Geofísicas, Universidad Nacional de La Plata, Paseo del Bosque s/n, (B1900FWA) La Plata, Argentina
3  Instituto de Astrofísica La Plata, IALP, CONICET-UNLP, Argentina
4  Institut d'Estudis Espacials de Catalunya, Ed. Nexus, c/Gran Capità 2, 08034 Barcelona, Spain

(Received 18 May 2005 / Accepted 9 July 2005)

We study the formation and evolution of DA white dwarfs, the progenitors of which have experienced a late thermal pulse (LTP) shortly after the departure from the thermally pulsing AGB. To this end, we compute the complete evolution of an initially  $2.7~M_{\odot}$ star all the way from the zero-age main sequence to the white dwarf stage. We find that most of the original H-rich material of the post-AGB  remnant is burnt during the post-LTP evolution, with the result that, at entering its white dwarf cooling track, the remaining H envelope becomes $10^{-6}~M_{\odot}$ in agreement with asteroseismological inferences for some ZZ Ceti stars.

Key words: stars: evolution -- stars: abundances -- stars: AGB stars: interiors -- stars: white dwarfs -- stars: oscillations

© ESO 2005