Issue |
A&A
Volume 527, March 2011
|
|
---|---|---|
Article Number | A5 | |
Number of page(s) | 7 | |
Section | Stellar structure and evolution | |
DOI | https://doi.org/10.1051/0004-6361/201015895 | |
Published online | 18 January 2011 |
Mixing in classical novae: a 2-D sensitivity study⋆
1
Departament de Física i Enginyeria Nuclear, EUETIBUniversitat Politècnica
de Catalunya,
c/Comte d’Urgell 187,
08036
Barcelona,
Spain
e-mail: jordi.jose@upc.edu
2
Institut d’Estudis Espacials de Catalunya,
c/Gran Capità 2–4, Ed.
Nexus-201, 08034
Barcelona,
Spain
3
Departament de Física Aplicada, Universitat Politècnica de
Catalunya, c/Esteve Terrades
5, 08860
Castelldefels,
Spain
4
Department of Physics & Astronomy, Stony Brook
University, Stony
Brook, NY
11794-3800,
USA
5
Dipartimento di Fisica “Enrico Fermi”, Università di Pisa and
INFN, Sezione di Pisa, Largo B.
Pontecorvo 3, 56127
Pisa,
Italy
Received:
8
October
2010
Accepted:
24
November
2010
Context. Classical novae are explosive phenomena that take place in stellar binary systems. They are powered by mass transfer from a low-mass, main sequence star onto a white dwarf. The material piles up under degenerate conditions and a thermonuclear runaway ensues. The energy released by the suite of nuclear processes operating at the envelope heats the material up to peak temperatures of ~(1−4) × 108 K. During these events, about 10-4−10-5M⊙, enriched in CNO and other intermediate-mass elements, are ejected into the interstellar medium. To account for the gross observational properties of classical novae (in particular, a metallicity enhancement in the ejecta above solar values), numerical models assume mixing between the (solar-like) material transferred from the companion and the outermost layers (CO- or ONe-rich) of the underlying white dwarf.
Aims. The nature of the mixing mechanism that operates at the core-envelope interface has puzzled stellar modelers for about 40 years. Here we investigate the role of Kelvin-Helmholtz instabilities as a natural mechanism for self-enrichment of the accreted envelope with core material.
Methods. The feasibility of this mechanism is studied by means of the multidimensional code FLASH. Here, we present a series of 9 numerical simulations perfomed in two dimensions aimed at testing the possible influence of the initial perturbation (duration, strength, location, and size), the resolution adopted, or the size of the computational domain on the results.
Results. We show that results do not depend substantially on the specific choice of these parameters, demonstrating that Kelvin-Helmholtz instabilities can naturally lead to self-enrichment of the accreted envelope with core material, at levels that agree with observations.
Key words: novae, cataclysmic variables / nuclear reactions, nucleosynthesis, abundances / convection / hydrodynamics / instabilities / turbulence
Movie is only available in electronic form at http://www.aanda.org
© ESO, 2011
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