A Review of the Thermonuclear Runaway Model of a Nova Outburst

1977 ◽  
pp. 189-204 ◽  
Author(s):  
Warren M. Sparks ◽  
Sumner Starrfield ◽  
James W. Truran
Keyword(s):  
Thermonuclear Runaway ◽  
Nova Outburst

scholarly journals Classical Novae – Before and After Outburst

1988 ◽  
Vol 108 ◽  
pp. 226-231
Author(s):  
Mario Livio
Keyword(s):  
White Dwarf ◽  
Main Sequence ◽  
Orbital Parameters ◽  
Classical Novae ◽  
Classical Nova ◽  
Before And After ◽  
Low Mass ◽  
Orbital Periods ◽  
Thermonuclear Runaway ◽  
Nova Outburst

Classical nova (CN) and dwarf nova (DN) systems have the same binary components (a low-mass main sequence star and a white dwarf) and the same orbital periods. An important question that therefore arises is: are these systems really different ? (and if so, what is the fundamental difference ?) or, are these the same systems, metamorphosing from one class to the other ?The first thing to note in this respect is that the white dwarfs in DN systems are believed to accrete continuously (both at quiescence and during eruptions). At the same time, both analytic (e.g. Fujimoto 1982) and numerical calculations show, that when sufficient mass accumulates on the white dwarf, a thermonuclear runaway (TNR) is obtained and a nova outburst ensues (see e.g. reviews by Gallagher and Starrfield 1978, Truran 1982). It is thus only natural, to ask the question, is the fact that we have not seen a DN undergo a CN outburst (in about 50 years of almost complete coverage) consistent with observations of DN systems ? In an attempt to answer this question, we have calculated the probability for a nova outburst not to occur (in 50 years) in 86 DN systems (for which at least some of the orbital parameters are known).

scholarly journals Nova Outburst Due to Accretion of H-Rich Matter onto White Dwarfs

1979 ◽  
Vol 53 ◽  
pp. 290-293
Author(s):  
G. Siegfried Kutter ◽  
Warren M. Sparks
Keyword(s):  
White Dwarf ◽  
White Dwarfs ◽  
Classical Novae ◽  
Secondary Star ◽  
Rich Material ◽  
Thermonuclear Runaway ◽  
Nova Outburst ◽  
Physical Realism ◽  
Degenerate Base

We assume that the outburst of classical novae is the result of transfer of H-rich material from a red secondary star to a He or C/O white dwarf and the development of a thermonuclear runaway in the e-degenerate “base of the accreted H-rich envelope. Based on these assumptions, we have investigated this problem in several stages of increasing theoretical complexity and physical realism.

scholarly journals On the Time-Scale for Turn-Off of a Nova After the Outburst

1979 ◽  
Vol 53 ◽  
pp. 274-279
Author(s):  
Sumner Starrfield
Keyword(s):  
Chemical Composition ◽  
White Dwarf ◽  
Time Scale ◽  
Light Curves ◽  
Substantial Agreement ◽  
The Past ◽  
Thermonuclear Runaway ◽  
Mass Ejection ◽  
Nova Outburst

It is now generally accepted that a nova outburst is caused by a thermonuclear runaway (TR) in the accreted hydrogen rich envelope of a carbon white dwarf. Over the past few years we have studied the evolution of such runaways and have shown that the calculated evolutionary sequences are in substantial agreement with the observations (Starrfield, et. al. 1978; Sparks, et. al. 1978). In the published work we have varied the white dwarf mass, the envelope mass, the accreted envelope mass, and the chemical composition in the envelope (Starrfield, et. al. 1976; Gallagher and Starrfield 1978). In all cases we find that a TR results in mass ejection and the luminosity variations of this ejected material can reproduce the observed light curves of the fast and slow novae.

scholarly journals Nova Modeling

1980 ◽  
Vol 5 ◽  
pp. 505-508
Author(s):  
Warren M. Sparks ◽  
G. Siegfried Kutter ◽  
Sumner Starrfield ◽  
James W. Truran
Keyword(s):  
White Dwarf ◽  
Feedback Loop ◽  
Birth Rate ◽  
Energy Generation ◽  
Close Binary ◽  
Theoretical Studies ◽  
Rich Material ◽  
Thermonuclear Runaway ◽  
Nova Outburst ◽  
Recurrent Nature

The mass and energy of nova ejecta are 10-5 - 10-4M⊚ and 1044 - 1045 ergs, respectively (Payne-Gaposchkin 1957). Comparison of these quantities with the mass (1 M⊚) and binding energy (1051 erg) of the erupting white dwarf implies that the nova outburst is a surface event. From an average of two or three novae detected each year, it is estimated that the rate of novae is 40-50 per year in our galaxy (Payne-Gaposchkin 1954) . Comparing this rate with a white dwarf birth rate of 2 per year in our galaxy (Weidemann 1968), we conclude that the nova outburst is a recurrent phenomenon (cf. Ford 1978). The recurrent nature also implies that the white dwarf cannot be drastically altered from event to event, thus giving further evidence for a surface event. The argument of recurrency become even stronger when it is realized that observations strongly indicate a close binary structure for the nova candidates—the white dwarf and a red companion (Kraft 1964).Kraft (1963) proposed the following hypothesis. The red companion overflows its Roche lobe and supplies hydrogen-rich material to an accretion disk around the white dwarf. This material eventually accretes onto the white dwarf, forming an hydrogen-rich envelope whose base is electron-degenerate. As the accretion proceeds, the temperature at the base of this envelope increases. This has little effect on the pressure, but greatly increases the thermonuclear energy generation. The thermonuclear energy generation, in turn, increases the temperature. This positive feedback loop leads to a thermonuclear runaway, which Kraft proposed as the cause of the nova outburst. A large number of theoretical studies based on this model have been carried out. These studies are presented in order of increasing realism and complexity in the following sections.

scholarly journals Hydrodynamic Studies of the Nova Outburst

1980 ◽  
Vol 58 ◽  
pp. 635-640
Author(s):  
S. Starrfield
Keyword(s):  
Light Curve ◽  
White Dwarf ◽  
Observational Studies ◽  
Theoretical Studies ◽  
Elemental Abundances ◽  
The Past ◽  
Thermonuclear Runaway ◽  
Nova Outburst ◽  
Made In ◽  
Observed Behavior

Over the past few years, significant advances have been made in our understanding of the nova outburst. The theoretical studies have shown not only that a thermonuclear runaway in the envelope of a white dwarf reproduces the gross features of the nova outburst (c.f.; Starrfield, Sparks, and Truran 1978, Sparks, Starrfield, and Truran, 1978, Gallagher and Starrfield 1978), but also made important predictions regarding the observed behavior of the outburst itself. The observational studies have provided us with new data concerning the evolution of the bolometric light curve of a nova during outburst, the elemental abundances in the ejecta, the formation of dust during the outburst, and the structure of nova binaries (c.f., Gallagher and Starrfield 1978).

scholarly journals Remarks on the Evolutionary Status of Cataclysmic Variables

1982 ◽  
Vol 69 ◽  
pp. 415-415
Author(s):  
N. Vogt
Keyword(s):  
Cataclysmic Variables ◽  
Time Interval ◽  
Evolutionary Status ◽  
Physical Reason ◽  
Dwarf Nova ◽  
Secular Evolution ◽  
Short Period ◽  
Period Decrease ◽  
Thermonuclear Runaway ◽  
Nova Outburst

The basic binary parameters (masses, system dimensions) of all cataclysmic variables are essentially identical, but there is a great variety in the outburst behaviour. Since there is no evident physical reason for this, it is suggested that nova and dwarf nova variability are periodically repeating states of activity of the same binary. After the nova eruption first follows a postnova state (very low disc mass), later the dwarf nova states BV Pup, U Gem and Z Cam (slowly increasing disc mass and outburst frequency, finally standstills), and finally the UX UMa state (permanent standstill) which is terminated by a new nova outburst. The mass of the disc increases continuously during this cycle. Also the mean mass transfer and accretion rates vary slowly from 1018 g s-1 at beginning and end of the cycle to 1016 g s-1 at mid-cycle, as a U Gem star. The nova outburst is understood in terms of a thermonuclear runaway near the surface of the white dwarf, the dwarf nova outburst is due to intermittent accretion of gas which was accumulated in the outer disc during quiescence (several arguments in favor of this model are given). The time interval between consecutive nova outbursts is of the order of 105 years. The secular evolution of a cataclysmic binary is characterized by a period decrease from 10h to 1h5 in a time scale of 1010 years. The star probably passes the period gaps in the ultra-short period domain in form of no-contact configurations.

scholarly journals 10. General Discussion

1960 ◽  
Vol 10 ◽  
pp. 677-679 ◽  
Keyword(s):  
Yield Curve ◽  
Fission Products ◽  
Heavy Elements ◽  
Sikhote Alin ◽  
Heavy Nuclei ◽  
Fission Yield ◽  
Element Abundances ◽  
The Earth ◽  
R Process ◽  
Nova Outburst

1. p. SELINOV: Anomalous abundances of Te and Xe isotopes in meteorites and in the Earth permit us to draw some conclusions concerning the age of uranium and the processes of nucleogenesis. According to the estimate by Hoyle the amount of 254Cf disintegrated during a super-nova outburst is of the order of io29 g or io~4 of the stellar mass. According to the fission-yield curve the isotopes of Te comprise about 1 % of the mass of fission products. The abundances of Te 128-131 are anomalously high, due to the fission of heavy nuclei. The element abundances do not permit us to draw any conclusions about the r-process. The isotopes of Te and Xe with even mass numbers give evidence in favour of the r-process (anomalously high abundances). But the amount of Te in meteorites and in Earth is about 1000 times less than it should be if formed during the outburst. The Sikhote- Alin meteorite shows the same anomaly. We may conclude that the heavy elements of the solar system have been formed not in a single super-nova outburst, but as a result of mixing from the totality of outbursts. According to Hoyle, this gives a definite estimate for the age of uranium.

scholarly journals A review of the classical nova outburst

1987 ◽  
Vol 131 (1-2) ◽  
pp. 379-393 ◽  
Author(s):  
S. Starrfield ◽  
W. M. Sparks
Keyword(s):  
Classical Nova ◽  
Nova Outburst

scholarly journals Two-dimensional simulations of mixing in classical novae: The effect of white dwarf composition and mass

2018 ◽  
Vol 619 ◽  
pp. A121 ◽  
Author(s):  
Jordi Casanova ◽  
Jordi José ◽  
Steven N. Shore
Keyword(s):  
White Dwarf ◽  
Binary Systems ◽  
Main Sequence ◽  
Chemical Species ◽  
Two Dimensions ◽  
Classical Novae ◽  
Nova Shells ◽  
Solar Abundances ◽  
Low Mass ◽  
Thermonuclear Runaway

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 either a CO or ONe white dwarf. The material accumulates for 104–105 yr until ignition under degenerate conditions, resulting in a thermonuclear runaway. The nuclear energy released produces peak temperatures of ∼0.1–0.4 GK. During these events, 10−7−10−3 M⊙ enriched in intermediate-mass elements, with respect to solar abundances, are ejected into the interstellar medium. However, the origin of the large metallicity enhancements and the inhomogeneous distribution of chemical species observed in high-resolution spectra of ejected nova shells is not fully understood. Aims. Recent multidimensional simulations have demonstrated that Kelvin-Helmholtz instabilities that operate at the core-envelope interface can naturally produce self-enrichment of the accreted envelope with material from the underlying white dwarf at levels that agree with observations. However, such multidimensional simulations have been performed for a small number of cases and much of the parameter space remains unexplored. Methods. We investigated the dredge-up, driven by Kelvin-Helmholtz instabilities, for white dwarf masses in the range 0.8–1.25 M⊙ and different core compositions, that is, CO-rich and ONe-rich substrates. We present a set of five numerical simulations performed in two dimensions aimed at analyzing the possible impact of the white dwarf mass, and composition, on the metallicity enhancement and explosion characteristics. Results. At the time we stop the simulations, we observe greater mixing (∼30% higher when measured in the same conditions) and more energetic outbursts for ONe-rich substrates than for CO-rich substrates and more massive white dwarfs.

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