10 Gyr of classical nova explosions (original) (raw)

Nucleosynthetic imprints from classical nova explosions: past to present

Proceedings of 10th Symposium on Nuclei in the Cosmos — PoS(NIC X), 2009

Classical novae are dramatic stellar explosions that take place in the accreted envelopes of white dwarfs in close binary systems. These unique cataclysmic events constitute a crucible where different scientific disciplines merge, including astrophysics, nuclear and atomic physics, cosmochemistry, high-energy physics or computer science. In this paper, we will focus on the nucleosynthesis accompanying such explosions. Theoretical predictions will be compared with the elemental abundances inferred from observations of the nova ejecta as well as with the isotopic abundance ratios measured in meteoritic grains. Special emphasis will be given to the interplay between nova outbursts and the Galactic abundance pattern. Results from recent simulations of nova explosions in cataclysmic primordial binaries will be also outlined. Finally, we will stress the key role played by nuclear physics in our understanding of these explosive phenomena by means of recent experiments and a thorough account of the impact of nuclear uncertainties. Hints on possible key nuclear physics experiments will be given.

Nucleosynthesis in classical nova explosions

Journal of Physics G: Nuclear and Particle Physics, 2007

Classical novae are fascinating stellar explosions at the crossroads of stellar astrophysics, nuclear physics, and cosmochemistry. In this review, we briefly summarize 30 years of nucleosynthesis studies, with special emphasis on recent advances in nova theory (including multidimensional models) as well as on experimental efforts to reduce nuclear uncertainties affecting critical reaction rates. Among the topics that are covered, we outline the interplay between nova outbursts and the galactic chemical abundances, the synthesis of radioactive nuclei of interest for γ-ray astronomy, such as 7 Li, 22 Na or 26 Al, and the potential discovery of presolar meteoritic grains likely condensed in nova shells.

Nucleosynthesis in stellar explosions: Type Ia supernovae, classical novae, and type I X-ray bursts

2019

Nuclear astrophysics aims at understanding the cosmic origin of the chemical elements and the energy generation in stars. It constitutes a truly multidisciplinary arena that combines tools, developments, and achievements in theoretical astrophysics, observational astronomy, cosmochemistry, and nuclear physics: the emergence of high-energy astrophysics with space-borne observatories has opened new windows to observe the Universe, from a novel panchromatic perspective; supercomputers have provided astrophysicists with the required computational capabilities to study the evolution of stars in a multidimensional framework; cosmochemists have isolated tiny pieces of stardust embedded in primitive meteorites, giving clues on the processes operating in stars as well as on the way matter condenses to form solids; and nuclear physicists have measured reactions near stellar energies, using stable and radioactive ion beam facilities. This paper shows provides a comprehensive insight into the nucleosynthesis accompanying stellar explosions, with particular emphasis on thermonuclear supernovae, classical novae, and type I X-ray bursts.

Prospects in Classical Nova Modeling and Nucleosynthesis

Nuclear Physics A, 2005

Classical novae are fascinating stellar events, at the crossroads of astrophysics, nuclear physics and cosmochemistry. In this review, we outline the history of nova modeling with special emphasis on recent advances and perspectives in multidimensional simulations. Among the topics that are covered, we analyze the interplay between nova outbursts and the Galactic chemical abundances, the synthesis of radioactive nuclei of interest for gamma-ray astronomy, such as 7 Li, 22 Na or 26 Al, and the recent discovery of presolar meteoritic grains, likely condensed in nova shells. 1. Nuclear ashes: Classical novae and Galactic nucleosynthesis Classical novae are close binary systems consisting of a white dwarf, and a large main sequence (or a more evolved) star. The companion overfills its Roche lobe and matter flows through the inner Lagrangian point, leading to the formation of an accretion disk around the compact star. A fraction of this (H-rich) matter ultimately ends up on top of the white dwarf, where it is gradually compressed up to the point when ignition conditions to drive a thermonuclear runaway (hereafter, TNR) are reached. The thermonuclear origin of nova outbursts was first theorized by Schatzman [36,37]. Modern multiwavelength observations and numerical simulations (pioneered by the early hydro models of Starrfield et al. [40]) have drawn a basic picture, usually referred to as the thermonuclear runaway model. Since then, several groups have attempted to improve our understanding of these dramatic stellar events, including state-of-the-art nova nucleosynthesis studies with spherically symmetric (or 1-D) hydro codes (see [26,21,43], and references therein) or preliminary multi-D approaches [13,14,24,25]. Nuclear physics plays a crucial role in the course of the explosion. As material from the accretion disk piles up on top of the (CO or ONe) white dwarf, the first nuclear reactions take place. This follows a rise in temperature since degenerate conditions unable the star to readjust the hydrostatic equilibrium by an envelope expansion and, as a result, a TNR ensues. The triggering reaction is 12 C(p,γ), which initiates the 'cold' CNO cycle. At very early stages of the explosion, the main nuclear activity is driven by 12 C(p, γ) 13 N(β +) 13 C(p, γ) 14 N. But as the temperature rises, the characteristic time for proton capture reactions on 13 N becomes shorther than its β + decay time, initiating the 'hot' CNO cycle. This is accompanyied by proton capture reactions onto 14 N, leading to 15 O, as well as by 16 O(p,γ) 17 F (near peak temperature, T peak). At this stage, the envelope exhibits the presence of significant amounts of 13 N, 14,15 O and 17 F. Indeed, it is the decay of these

Nucleosynthesis in Stellar Explosions

Astrophysics and Space Science Library, 1984

This is a preprint of a paper intended for publication in a journal or proceedings. Since changes may be made before publication, this preprint is made available with the un derstanding that it will not be cited or reproduced without the permission of the author.

Beacons in the sky: Classical novae vs. X-ray bursts

The European Physical Journal A, 2006

Thermonuclear runaways are at the origin of some of the most energetic and frequent stellar cataclysmic events. In this review talk, we outline our understanding of the mechanisms leading to classical nova explosions and X-ray bursts, together with their associated nucleosynthesis. In particular, we focus on the interplay between nova outbursts and the Galactic chemical abundances (where 13 C, 15 N, and 17 O constitute the likely imprints of many nova outbursts during the overall 10 Gyr of Galactic history), the synthesis of radioactive nuclei of interest for gamma-ray astronomy (7 Be-7 Li, 22 Na, or 26 Al), the endpoint of nova nucleosynthesis, based on theoretical and observational grounds, and the recent discovery of presolar meteoritic grains, both in the Murchison and Acfer 094 meteorites, likely condensed in nova shells. Recent progress in the modeling of X-ray bursts as well as an insight into the input nuclear physics requests, for both novae and X-ray bursts, will also be presented.

Nuclear Processes in Stellar Explosions

Fission and Properties of Neutron-Rich Nuclei, 2008

We know two kind of stellar explosion events; shock induced explosions of core collapsing massive stars known as type 11 supemovae, and accretion induced thermonuclear explosions such as type Ia supernovae, X-ray bursts, and novae in accreting binary systems. The type I1 supernova shock front causes rapid increase of density and temperature conditions in the stellar material initiating fast neutron or gamma induced nucleosynthesis processes such as the r-process and the p-process which contribute to the heavy element abundance distribution in our universe. Thermonuclear stellar explosions on the other hand are driven by nuclear ignition of dense stellar material at highly electron degenerate conditions. The ignition conditions are defined by the reaction rates of heavy ion fusion processes of stellar core material for type Ia supernovae, or by rapid nuclear fusion processes such as the hot CNO cycles or the rp-process in the stellar atmosphere of freshly accreted matter. This paper will provide a summary of the nucleosynthesis signatures of the rapid nucleosynthesis processes in stellar explosions and will highlight their impact on the associated energy release and the production of heavy elements as observed in our galaxy.