| Issue |
EAS Publications Series
Volume 82, 2019
Astro Fluid: An International Conference in Memory of Professor Jean-Paul Zahn's Great Scientific Achievements
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|---|---|---|
| Page(s) | 183 - 187 | |
| Section | Seismology and Stellar Structure, Evolution and Rotation | |
| DOI | https://doi.org/10.1051/eas/1982018 | |
| Published online | 21 June 2019 | |
A.S. Brun, S. Mathis, C. Charbonnel and B. Dubrulle (eds)
EAS Publications Series, 82 (2019) 183-187
Fingering convection in accreting hydrogen white dwarfs
1 Instituto de Astrofísica de La Plata, (UNLP,CONICET). Facultad de Ciencias Astronómicas y Geofísicas, Universidad Nacional de La Plata, Argentina
2 Université de Toulouse, UPS-OMP, IRAP, France and CNRS, IRAP, 14 avenue Edouard Belin, 31400 Toulouse, France
3 Université de Toulouse, UPS-OMP, IRAP, France and CNRS, IRAP, 14 avenue Edouard Belin, 31400 Toulouse, France
4 Instituto de Astrofísica de La Plata, (UNLP,CONICET). Facultad de Ciencias Astronómicas y geofísicas, Universidad Nacional de La Plata, Argentina
The accretion of heavy material from debris disk on the surface of hydrogen-rich white dwarfs induces a double diffusivity instability known as the fingering convection. It leads to an efficient extra mixing which brings the accreted material deeper in the star than by considering only mixing in the surface dynamical convection zone, in a time scale much shorter than that of gravitational settling. We performed numerical simulations of a continuous accretion of heavy material having a bulk Earth composition on the two well studied DAZ and ZZ Ceti pulsators GD 133 and G 29-38. We find that the existence of fingering convection implies much larger accretion rates to explain the observed abundances than previous estimates based on the standard mixing length theory and gravitational settling only.
© EAS, EDP Sciences, 2019