IOP PUBLISHING JOURNAL OF PHYSICS G: NUCLEAR AND PARTICLE PHYSICS J. Phys. G: Nucl. Part. Phys. 35 (2008) 014024 (9pp) doi:10.1088/0954-3899/35/1/014024 10 Gyr of classical nova explosions Jordi Jos´ e 1,3 and Margarita Hernanz 2,3 1 Departament de F´ ısica i Enginyeria Nuclear, EUETIB, Universitat Polit` ecnica de Catalunya, C./ Comte d’Urgell 187, E-08036 Barcelona, Spain 2 Institut de Ci` encies de l’Espai (CSIC), Campus UAB, Facultat de Ci` encies, Torre C5-parell, 2 planta, E-08193 Bellaterra (Barcelona), Spain 3 Institut d’Estudis Espacials de Catalunya, Ed. Nexus-201, C./ Gran Capit` a 2-4, E-08034 Barcelona, Spain E-mail: jordi.jose@upc.edu and hernanz@ieec.uab.es Received 2 July 2007 Published 13 December 2007 Online at stacks.iop.org/JPhysG/35/014024 Abstract Classical novae are stellar explosions in cataclysmic binary systems, consisting of a compact white dwarf star (CO or ONe-rich) and a low-mass, main-sequence companion (typically, a K or M dwarf of solar composition). The system is close enough (orbital periods ranging between 1 and 15 h), hence allowing mass transfer episodes driven by overflows of the companion star. This matter flow forms an accretion disk that surrounds the white dwarf, and ultimately accumulates on its surface (at a rate M = 10 −9 –10 −10 M ⊙ yr −1 ), building up an envelope under semi-degenerate conditions until a violent thermonuclear runaway ensues. Classical novae are believed to be major sources of the Galactic 15 N, 17 O and 13 C, with a minor contribution on a number of additional species, mainly 7 Li and 26 Al. But there are reasons to believe that these nucleosynthetic features have varied during the overall 10 Gyr of Galactic history. In this paper, we review recent progress on the characterization of primordial novae, that is, novae exploding in primordial cataclysmic binaries, and will compare their expected nucleosynthetic pattern with that of classical novae. Emphasis is made on the dominant nuclear paths during the explosion and on a thorough comparison with other explosive sites, such as type-I x-ray bursts. (Some figures in this article are in colour only in the electronic version) 1. Introduction Stars are born by gravitational collapse of huge gas clouds and their lives end, after fuel consumption, in the form of compact stellar remnants. Depending on the initial mass of the star its fate, as an individual object, leads to a white dwarf, a neutron star or a black hole. 0954-3899/08/014024+09$30.00 © 2008 IOP Publishing Ltd Printed in the UK 1