The Classical Nova Outburst

1986 ◽  
Vol 89 ◽  
pp. 224-248
Author(s):  
Sumner G. Starrfieldt
Keyword(s):  
Angular Momentum ◽  
White Dwarf ◽  
Theoretical Calculations ◽  
Close Binary System ◽  
Close Binary ◽  
Proton Proton ◽  
Thermonuclear Burning ◽  
Classical Nova ◽  
Nova Outburst ◽  
Reaction Chain

In this review I will present and discuss both the nova outburst and the theoretical calculations related to its cause and evolution. I use the commonly accepted model for a nova: a close binary system with one member a white dwarf and the other member a larger, cooler star that fills its Roche lobe. Because it fills its lobe, any tendency for it to grow in size because of evolutionary processes or for the lobe to shrink because of angular momentum losses will cause a flow of gas through the inner Lagrangian point into the lobe of the white dwarf. The size of the white dwarf is small compared to the size of its lobe and the high angular momentum of the transferred material causes it to spiral into an accretion disk surrounding the white dwarf. Some viscous process, as yet unknown, acts to transfer mass inward and angular momentum outward through the disk so that a fraction of the material lost by the secondary ultimately ends up on the white dwarf. Over a long period of time, the accreted layer will grow in thickness until the bottom reaches a temperature that is high enough to initiate thermonuclear burning of hydrogen by the proton-proton reaction chain. The further evolution of thermonuclear burning on the white dwarf now depends upon the mass and luminosity of the white dwarf, the rate of mass accretion, and the chemical composition of the reacting layer.

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 The Effect of a Close Binary Companion on a Nova Outburst

1979 ◽  
Vol 53 ◽  
pp. 531-531
Author(s):  
Jim MacDonald
Keyword(s):  
Simple Model ◽  
White Dwarf ◽  
Energy Generation ◽  
Close Binary ◽  
Additional Energy ◽  
Model Based ◽  
Hydrodynamic Calculations ◽  
Cno Abundances ◽  
Nova Outburst

We compare two hydrodynamic calculations of thermonuclear runaways in material accreted by a 1M⊙ white dwarf of initial luminosity 10−3L⊙. In both cases the CNO abundances are taken to be near solar (ZCNO = 0.014). The only difference between the calculations is that in one sequence of models (seq.B) the additional energy generation due to the interaction between the expanding nova envelope and a close red dwarf companion is allowed for, using a simple model based on that of Paczynski (1976).

scholarly journals The Near-Synchronous Polar Candidate V4633 Sgr (Nova Sagittarii 1998)

2004 ◽  
Vol 190 ◽  
pp. 176-177
Author(s):  
Y. Lipkin ◽  
E. M. Leibowitz
Keyword(s):  
Angular Momentum ◽  
Momentum Transfer ◽  
White Dwarf ◽  
Moment Of Inertia ◽  
The Other ◽  
Angular Momentum Transfer ◽  
Classical Nova ◽  
Order Of Magnitude ◽  
Photometric Monitoring ◽  
The Moment

AbstractThe classical nova V4633 Sgr (1998) exhibits two photometric periodicities. The shorter period (P1=3.01 hr) is stable, while the other one, longer by ~2.5%, has decreased monotonically since shortly after the nova eruption, with Ṗ2 ≈ –10−6 (Lipkin et al. 2001).Here we report on results of photometric monitoring of the star in 2001 and 2002. During our observations, the longer period decreased more, and in 2002 it was only 1.8% longer than P1 The decrease rate (Ṗ2) in 2001-2002 was an order of magnitude smaller than in 1998-2000.These new results support the Near-Synchronous Polar classification which was suggested for V4633 Sgr (Lipkin et al. 2001). In this model, the longer period of V4633 Sgr is the spin of the white dwarf, and its variation since 1998 reflects changes in the moment of inertia of the white dwarf, and angular momentum transfer in the system following the nova eruption.

scholarly journals Effects of Rotation on Helium Accreting White Dwarf

2004 ◽  
Vol 215 ◽  
pp. 571-572 ◽  
Author(s):  
S.-C. Yoon ◽  
N. Langer
Keyword(s):  
Angular Momentum ◽  
White Dwarf ◽  
Spherical Symmetry ◽  
Binary Systems ◽  
Close Binary ◽  
Type Ia Supernovae ◽  
Classical Studies ◽  
Type Ia ◽  
Effects Of Rotation ◽  
Ia Supernovae

Classical studies of accreting white dwarfs have assumed spherical symmetry. However, it is believed that in close binary systems the transfered matter carries angular momentum to spin up the accreting star. Here, we present preliminary results of CO white dwarf models which accrete helium rich matter with effects of rotation considered, in the context of the Sub-Chandrasekhar mass scenario for Type Ia supernovae.

An Extremely Massive White Dwarf of the Symbiotic Classical Nova V407 Cyg as Suggested by the RS Oph and U SCO Models

2012 ◽  
Vol 21 (1-2) ◽  
Author(s):  
I. Hachisu ◽  
M. Kato
Keyword(s):  
Light Curve ◽  
White Dwarf ◽  
Early Phase ◽  
Symbiotic Star ◽  
X Ray ◽  
Classical Nova ◽  
Optical Light Curve ◽  
Nova Outburst

AbstractWe have analyzed the optical light curve of the symbiotic star V407 Cyg that underwent a classical nova outburst in 2010 March. Being guided by a supersoft X-ray phase observed during days 20-40 after the nova outburst, we are able to reproduce the light curve during a very early phase of the nova outburst. Our model consists of an outbursting white dwarf and an extended equatorial disk. An extremely massive white dwarf of 1.35-1.37 M

scholarly journals On the Masses of the White Dwarfs in Classical Nova Systems

1989 ◽  
Vol 114 ◽  
pp. 498-506 ◽  
Author(s):  
James W. Truran ◽  
Mario Livio
Keyword(s):  
White Dwarf ◽  
Binary Systems ◽  
Close Binary ◽  
Critical Parameters ◽  
Significant Progress ◽  
Classical Novae ◽  
The Past ◽  
Close Binary Systems ◽  
Classical Nova ◽  
The Masses

Significant progress in our understanding of the nature of the outbursts of the classical novae has occurred over the past two decades (see, e.g., reviews by Truran 1982; Starrfield 1986). Their outbursts are now understood to be driven by thermonuclear runaways proceeding in the accreted hydrogen-rich shells on the white dwarf components of close binary systems. Critical parameters which serve to dictate the varied characteristics of the observed outbursts include the intrinsic white dwarf luminosity, the rate of mass accretion, the composition of the envelope matter prior to runaway, and the white dwarf mass.

scholarly journals Recurrence of Nova Explosions

1979 ◽  
Vol 53 ◽  
pp. 525-525 ◽  
Author(s):  
Kyoji Nariai ◽  
Ken’ichi Nomoto
Keyword(s):  
Binary System ◽  
White Dwarf ◽  
Close Binary System ◽  
Roche Lobe ◽  
Close Binary ◽  
Ignition Point ◽  
Almost All

It has been shown by many computations that a nova explosion is triggered by mass accretion onto a white dwarf in a close binary system. Such nova explosions will recur many times in the following way. When a certain amount of hydrogen-rich gas has been accreted on the white dwarf, a hydrogen-shell flash is ignited. Then the hydrogen-rich envelope expands greatly, which, in some cases, grows into a nova explosion. Almost all envelope mass is ejected into space or at least overflows its Roche lobe. After that the mass of the envelope increases again by accretion and the shell flash is ignited again. The period of such recurrence is given by τrec = ΔMH/(dM/dt), where dM/dt and ΔMH are the rate of accretion and the mass contained in the hydrogen-rich envelope at the ignition point.

scholarly journals Close binary evolution

2017 ◽  
Vol 609 ◽  
pp. A3 ◽  
Author(s):  
H. F. Song ◽  
G. Meynet ◽  
A. Maeder ◽  
S. Ekström ◽  
P. Eggenberger ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Angular Momentum ◽  
Binary System ◽  
Magnetic Fields ◽  
Close Binary System ◽  
Momentum Transport ◽  
Close Binary ◽  
Surface Magnetic Field ◽  
Angular Momentum Transport ◽  
Magnetic Braking

Context. Massive stars with solar metallicity lose important amounts of rotational angular momentum through their winds. When a magnetic field is present at the surface of a star, efficient angular momentum losses can still be achieved even when the mass-loss rate is very modest, at lower metallicities, or for lower-initial-mass stars. In a close binary system, the effect of wind magnetic braking also interacts with the influence of tides, resulting in a complex evolution of rotation. Aims. We study the interactions between the process of wind magnetic braking and tides in close binary systems. Methods. We discuss the evolution of a 10 M⊙ star in a close binary system with a 7 M⊙ companion using the Geneva stellar evolution code. The initial orbital period is 1.2 days. The 10 M⊙ star has a surface magnetic field of 1 kG. Various initial rotations are considered. We use two different approaches for the internal angular momentum transport. In one of them, angular momentum is transported by shear and meridional currents. In the other, a strong internal magnetic field imposes nearly perfect solid-body rotation. The evolution of the primary is computed until the first mass-transfer episode occurs. The cases of different values for the magnetic fields and for various orbital periods and mass ratios are briefly discussed. Results. We show that, independently of the initial rotation rate of the primary and the efficiency of the internal angular momentum transport, the surface rotation of the primary will converge, in a time that is short with respect to the main-sequence lifetime, towards a slowly evolving velocity that is different from the synchronization velocity. This “equilibrium angular velocity” is always inferior to the angular orbital velocity. In a given close binary system at this equilibrium stage, the difference between the spin and the orbital angular velocities becomes larger when the mass losses and/or the surface magnetic field increase. The treatment of the internal angular momentum transport has a strong impact on the evolutionary tracks in the Hertzsprung-Russell Diagram as well as on the changes of the surface abundances resulting from rotational mixing. Our modelling suggests that the presence of an undetected close companion might explain rapidly rotating stars with strong surface magnetic fields, having ages well above the magnetic braking timescale. Our models predict that the rotation of most stars of this type increases as a function of time, except for a first initial phase in spin-down systems. The measure of their surface abundances, together, when possible, with their mass-luminosity ratio, provide interesting constraints on the transport efficiencies of angular momentum and chemical species. Conclusions. Close binaries, when studied at phases predating any mass transfer, are key objects to probe the physics of rotation and magnetic fields in stars.

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