Classical novae at the crossroads of nuclear physics, astrophysics and cosmochemistry featuring Jordi José [Technical University of Catalonia, UPC (Barcelona, Spain)]

Hosted by: Adrià Casanovas (UPC-Barcelona)

Abstract: Classical novae are thermonuclear explosions that take place in the H-rich envelopes of accreting white dwarfs in stellar binary systems. The material piles up under degenerate conditions, driving a thermonuclear runaway. The energy released by the suite of nuclear processes operating at the envelope heats the material up to peak temperatures of (100 - 400) MK. During these events, about 10-7 - 10-4 solar masses, enriched in CNO, and sometimes, other intermediate-mass elements (e.g., Ne, Na, Mg, Al) are ejected into the interstellar medium. Infrared and ultraviolet observations of novae have confirmed grain formation in their expanding shells. This has raised the issue of the potential contribution of novae to the current inventory of presolar grains. I will review several studies that have led to the identification of a handful of presolar grains with isotopic signatures consistent with a nova origin. Mixing at the core-envelope interface still remains as an important unknown in the modeling of classical novae. I will review as well recent results from multidimensional simulations of mixing by hydrodynamic (Kelvin-Helmholtz) instabilities and shear. Strategies to export mixing prescriptions obtained from such  multidimensional simulations for follow-up studies with 1D codes will also be discussed. Finally, I will also present recent recurrent nova models, aimed at characterizing T CrB, a system that should undergo an explosion imminently. In most recurrent novae, the mass of the accreting white dwarf is expected to be very close to the Chandrasekhar value, as imposed by their short recurrence periods. Simulations suggest that such white dwarfs grow in mass, making recurrent novae likely candidates for thermonuclear supernovae.