Nucleosynthesis Accompanying Classical Nova Outbursts

Author(s):  
James W. Truran
1987 ◽  
Vol 93 ◽  
pp. 419-429
Author(s):  
A. Kovetz ◽  
D. Prialnik ◽  
M.M. Shara

AbstractAn evolutionary scenario for classical novae is proposed, which is intended to solve the discrepancies that exist between theory and observations: the space densities of classical novae deduced from surveys in the solar neighbourhood are lower by about two orders of magnitude than those predicted theoretically, and the mass transfer rates in nova binaries, as estimated from observed luminosities in quiescence, are higher than those allowed by the thermonuclear runaway model for nova outbursts. These discrepancies disappear if mass transfer (at a high rate) takes place for only a few hundred years before and a few hundred years after an eruption, but declines afterwards and remains off for most of the time between outbursts. We show that such a behavior is to be expected if one takes into account the variation of binary separation, due to mass ejection on the one hand and angular momentum losses on the other hand.One of the aspects of this scenario, on which we report in more detail, is the possibility of enhanced Roche-lobe overflow of the secondary, due to its expansion that results from irradiation by the high nova luminosity. We followed the evolution of a 0.5M⊙ main sequence star illuminated by a changing flux, typical of a classical nova. The numerical results indicate that, in spite of the slight binary separation that may occur after eruption, mass loss from the irradiated and thus bloated secondary should continue for a few hundred years. Other aspects of the variable Ṁ scenario are briefly summarized.


2018 ◽  
Vol 614 ◽  
pp. A141 ◽  
Author(s):  
V. Šimon

Aims. X Ser is a cataclysmic variable (CV) which erupted as a classical nova in 1903. In this work we use over 100 years of photometry to characterize the long-term light curve of X Ser, with the aim of interpreting the post-nova activity in X Ser in the context of behaviors in other old novae. Methods. This analysis of its long-term optical activity uses the data from the Digital Access to a Sky Century @ Harvard (DASCH), AAVSO, and Catalina Real-time Transient Survey databases, supplemented by the data of other authors. Results. We show that X Ser displays a strong complex activity with the characteristics of various CV types after the return to quiescence from its classical nova outburst. Both nova-like and dwarf nova (DN) features are present. The decaying branches of the individual post-nova outbursts display large mutual similarities and obey the Bailey law for outbursts of DNe. These outbursts of X Ser constitute a uniform group (inside-out outbursts), and their decaying branches can be explained by propagation of cooling front through the accretion disk. In the interpretation, X Ser rapidly transitioned to a thermal-viscous instability regime of the disk, initially only intermittently. The occurrence of the DN outbursts shortly after the end of the nova outburst suggests that the mass transfer rate into the disk was usually not sufficiently high to prevent a thermal-viscous instability of this post-nova. The very long orbital period, and hence large accretion disk of X Ser can contribute to this.


2003 ◽  
Vol 20 (4) ◽  
pp. 351-355 ◽  
Author(s):  
Jordi José ◽  
Margarita Hernanz ◽  
Sachiko Amari ◽  
Ernst Zinner

AbstractInfrared observations of nova light curves reveal that classical novae form grains in the expanding shells, ejected into the interstellar medium as a consequence of a violent outburst. Such grains contain nucleo-synthetic fingerprints of the nova explosion. In this paper, we analyse different isotopic signatures expected to be present in nova grains on the basis of detailed hydrodynamic calculations of CO and ONe novae and compare them with recent determinations of presolar nova grains from the Acfer 094 and Murchison meteorites.


2010 ◽  
Vol 513 ◽  
pp. L5 ◽  
Author(s):  
J. Casanova ◽  
J. José ◽  
E. García-Berro ◽  
A. Calder ◽  
S. N. Shore

2011 ◽  
Author(s):  
Jordi Casanova ◽  
Jordi Jose ◽  
Enrique García-Berro ◽  
Alan C. Calder ◽  
Steven N. Shore

2011 ◽  
Vol 7 (S281) ◽  
pp. 80-87 ◽  
Author(s):  
Jordi José ◽  
Jordi Casanova ◽  
Enrique García–Berro ◽  
Margarita Hernanz ◽  
Steven N. Shore ◽  
...  

AbstractRemarkable progress in the understanding of nova outbursts has been achieved through combined efforts in photometry, spectroscopy and numerical simulations. According to the thermonuclear runaway model, novae are powered by thermonuclear explosions in the hydrogen-rich envelopes transferred from a low-mass stellar companion onto a close white dwarf star. Extensive numerical simulations in 1-D have shown that the accreted envelopes attain peak temperatures ranging between 108 and 4 × 108 K, for about several hundred seconds, hence allowing extensive nuclear processing which eventually shows up in the form of nucleosynthetic fingerprints in the ejecta. Indeed, it has been claimed that novae can play a certain role in the enrichment of the interstellar medium through a number of intermediate-mass elements. This includes 17O, 15N, and 13C, systematically overproduced with respect to solar abundances, plus a lower contribution in a number of other species (A < 40), such as 7Li, 19F, or 26Al. At the turn of the XXI Century, classical novae have entered the era of multidimensional models, which provide a new insight into the physical mechanisms that drive mixing at the core-envelope interface.In this review, we will present hydrodynamic models of classical novae, from the onset of accretion up to the explosion and ejection stages, both for classical and recurrent novae, with special emphasis on their gross observational properties and their associated nucleosynthesis. The impact of nuclear uncertainties on the final yields will be discussed. Recent results from 2-D models of mixing during classical nova outbursts will also be presented.


1996 ◽  
Vol 158 ◽  
pp. 303-304
Author(s):  
M. Hernanz ◽  
J. José ◽  
J. Gómez

AbstractWe report on preliminary hydrodynamic simulations of thermonuclear runaways in the hydrogen-rich envelopes of accreting white dwarfs, leading to nova outbursts. A one-dimensional, Lagrangian, implicit, hydrodynamic code (Kutter & Sparks 1972) has been used to reproduce the gross features of a classical nova, from the onset of accretion, through the progress of the outburst up to the expansion stage, where significant mass loss takes place. Special interest is focused on the synthesis of 22Na and 26Al, for their interest in γ-ray line astrophysics. The γ-ray spectrum is built by means of a Monte Carlo simulation.


1996 ◽  
Vol 158 ◽  
pp. 281-287
Author(s):  
James MacDonald

AbstractMulti-wavelength observations have shown that, after optical decline, the stellar remnants of classical nova outbursts evolve at constant, near-Eddington, bolometric luminosity to high effective temperature (> 2 105 K), before turning off. Here we briefly review the observations of classical novae in this phase of evolution, and discuss what the soft X-ray observations tell us about the mass of the underlying white dwarf and the rate of mass change due to stellar winds and accretion from the stellar companion.


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