scholarly journals The Effect of the Nova Explosion on the Evolution of Cataclysmic Variables

1997 ◽  
Vol 163 ◽  
pp. 771-772
Author(s):  
T. Naylor ◽  
M.W. Somers
Keyword(s):  
Mass Transfer ◽  
White Dwarf ◽  
White Dwarfs ◽  
Cataclysmic Variables ◽  
Accretion Disc ◽  
Surface Layers ◽  
Secondary Star ◽  
Classical Nova ◽  
Nova Outbursts

Classical nova outbursts are thermonuclear explosions on the surfaces of the white dwarfs in cataclysmic variables. The explosion heats the surface layers of the white dwarf, which are expected to cool on a timescale of a hundred years. The hot white dwarf should have two obvious effects on the system.(1)It will heat the surface of the accretion disc and secondary star, increasing the overall luminosity of the system.(2)By irradiating the surface of the secondary star it may bloat it and drive more mass transfer, thus again increasing the overall luminosity.

scholarly journals BC Cassiopeiae: First detection of IW Andromedae-type phenomenon among post-eruption novae

2020 ◽  
Vol 72 (6) ◽  
Author(s):  
Taichi Kato ◽  
Naoto Kojiguchi
Keyword(s):  
Mass Transfer ◽  
White Dwarf ◽  
Transfer Rate ◽  
White Dwarfs ◽  
Mass Transfer Rate ◽  
Cataclysmic Variables ◽  
High Mass ◽  
Average Mass ◽  
Classical Nova ◽  
Decline Rate

Abstract IW And-type dwarf novae are a recently recognized group of cataclysmic variables which are characterized by a sequence of brightening from a standstill-like phase with damping oscillations often followed by a deep dip. We found that the supposed classical nova BC Cas which erupted in 1929 experienced a state of an IW And-type dwarf nova in 2018, 89 yr after the eruption. This finding suggests that a high mass-transfer rate following the nova eruption is associated with the IW And-type phenomenon. The mass of the white dwarf inferred from the decline rate of the nova is considerably higher than the average mass of the white dwarfs in cataclysmic variables, and these massive white dwarfs may be responsible for the manifestation of the IW And-type phenomenon.

scholarly journals Classical Novae in the Context of the Evolution of Cataclysmic Binaries

1990 ◽  
Vol 122 ◽  
pp. 313-324
Author(s):  
Hans Ritter
Keyword(s):  
Mass Transfer ◽  
White Dwarf ◽  
White Dwarfs ◽  
Mass Range ◽  
High Mass ◽  
Transfer Rates ◽  
Classical Novae ◽  
Secular Evolution ◽  
Cataclysmic Binaries ◽  
Nova Outbursts

AbstractIn this paper we explore to what extent the TNR model of nova outbursts and our current concepts of the formation and secular evolution of cataclysmic binaries are compatible. Specifically we address the following questions: 1) whether observational selection can explain the high white dwarf masses attributed to novae, 2) whether novae on white dwarfs in the mass range 0.6M⊙ ≲ M ≲ 0.9M⊙ can occur and how much they could contribute to the observed nova frequency, and 3) whether the high mass transfer rates imposed on the white dwarf in systems above the period gap can be accommodated by the TNR model of nova outbursts.

scholarly journals Masses and Magnetic Fields of White Dwarfs in Cataclysmic Variables

1989 ◽  
Vol 114 ◽  
pp. 337-340
Author(s):  
J.P. Lasota ◽  
J.M. Hameury ◽  
A.R. King
Keyword(s):  
Magnetic Field ◽  
Angular Momentum ◽  
Magnetic Fields ◽  
White Dwarf ◽  
White Dwarfs ◽  
Cataclysmic Variables ◽  
Strong Support ◽  
Drastic Reduction ◽  
Secondary Star ◽  
Maximum Magnetic Field

We show that the existence of the AM Her period spike implies (i) a unique white dwarf mass ≃ 0.6 − 0.7M⊙ for most magnetic CV’s (ii) nova explosions remove exactly the accreted mass from magnetic white dwarfs, and (iii) the maximum magnetic field for most CV’s is ≤ 4 × 107 G. The existence of the spike is very strong support for the idea that the period gap results from a drastic reduction of angular momentum losses when the secondary star becomes fully convective.

scholarly journals Episodic Mass Transfer: A Trigger for Nova Outbursts?

2011 ◽  
Vol 7 (S281) ◽  
pp. 88-95
Author(s):  
Robert Williams
Keyword(s):  
Mass Transfer ◽  
High Resolution ◽  
White Dwarf ◽  
Spectral Evolution ◽  
Secondary Star ◽  
Multiple Components ◽  
Line Widths ◽  
Alternative Scenarios ◽  
Nova Outbursts ◽  
Secular Increase

AbstractHigh resolution spectra of post-outburst novae show multiple components of ejected gas that are kinematically distinct. We interpret the observations in terms of episodes of enhanced mass transfer originating from the secondary star that result in the formation of discrete components of circumbinary gas and accretion onto the white dwarf (WD) that trigger nova outbursts. In this picture the concordance between absorption line velocities and emission line widths in most novae occurs as a result of the collision of the expanding nova ejecta with a larger mass of surrounding circumbinary gas. One implication of this model is that much of the accreted gas remains on the WD, leading to a secular increase in WD mass over each outburst event. Alternative scenarios to explain nova spectral evolution are possible that do not invoke circumbinary gas and a possible test of different models is proposed.

scholarly journals Mass Measurement of Accreting Magnetic White Dwarfs with Hard X-Ray Spectroscopy

1998 ◽  
Vol 188 ◽  
pp. 97-100
Author(s):  
M. Ishida ◽  
R. Fujimoto
Keyword(s):  
White Dwarf ◽  
White Dwarfs ◽  
Mass Measurement ◽  
Cataclysmic Variables ◽  
Magnetic Pole ◽  
X Ray ◽  
Secondary Star ◽  
Magnetic Cataclysmic Variables ◽  
Image Position ◽  
The Magnetic Field

Accreting magnetic white dwarfs are usually found as component stars in Magnetic Cataclysmic Variables (MCVs), in which a white dwarf with B = 105-8 G accepts mass from a late type (secondary) star via Roche Lobe overflow. Matter from the secondary is funneled by the magnetic field and concentrates on the magnetic pole(s) of the white dwarf. Since the accretion flow becomes highly supersonic, a standing shock wave is formed close to the white dwarf. The temperature of the plasma at the shock front reflects the gravitational potential and can be denoted as a function of the mass (M) and the radius (R) of the white dwarf as: Note here that the height of the shock is expected to be within 10% of the white dwarf radius, and hence neglected here.

scholarly journals Novae and Accretion Disc Evolution

1986 ◽  
Vol 89 ◽  
pp. 269-279
Author(s):  
G.T. Bath
Keyword(s):  
Mass Transfer ◽  
White Dwarf ◽  
Mass Loss Rate ◽  
Model Atmosphere ◽  
Accretion Disc ◽  
Dynamical Instability ◽  
Classical Nova ◽  
Nuclear Burning ◽  
Ultraviolet Photons ◽  
Eddington Limit

AbstractAt outburst the classical nova generates an extended optically-thick wind driven by radiation pressure in the continuum. At maximum light the optical luminosity is close to the Eddington-limit. The subsequent decline illustrates the interaction between radiation and matter in a wind which gradually thins as the mass loss rate falls at an approximately constant Eddington-limit luminosity. As the wind thins so the effective photosphere shrinks back into the underlying binary, and an increasing fraction of the radiation is emitted at ultraviolet wavelengths. Model atmosphere computations show how the increasing flux of ultraviolet photons is associated with the shell becoming more and more ionized through radiative ionization. Attempts to study the internal structure of the wind confirm that the luminosity must be close to the Eddington limit and must be expelled from close to the white dwarf surface. It is generally agreed that the outbursts are caused by runaway nuclear burning of accreted material at the white dwarf surface, but it is possible that some events of the classical nova type may be caused by runaway accretion at a super-critical rate.In dwarf novae very different behaviour is evident. The outbursts are located within the accretion disc and are generated either by mass-transfer bursts due to dynamical instability of the Roche-lobe filling star, or by an instability within the disc itself. In either case the eruption behaviour is due to an enhanced accretion flux through the accretion disc. One important aspect of the radiation hydrodynamics is the luminosity generated by impact of the mass-transfer stream with the accretion disc and penetration by the stream within the disc. Attempts at examining this penetration region are described and results compared with observed behaviour of disc evolution through the course of an outburst. The possibility that disc instabilities will not propogate in realistic discs which deviate from axial symmetry is considered.

scholarly journals Evolution and Outbursts of Cataclysmic Variables

2015 ◽  
Vol 2 (1) ◽  
pp. 152-155 ◽  
Author(s):  
S.-B. Qian ◽  
L.-Y. Zhu ◽  
E.-G. Zhao ◽  
E. Fernández Lajús ◽  
J. Zhang ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Hot Spot ◽  
Variable Mass ◽  
Cataclysmic Variables ◽  
Dark Spot ◽  
Secondary Star ◽  
Spot Activity ◽  
Activity Cycles ◽  
Nova Outbursts

Mass transfer and accretion are very important to understand the evolution and observational properties of cataclysmic variables (CVs). Due to the lack of an accretion disk, eclipsing profiles of polars are the best source to study the character of mass transfer in CVs. By analyzing long-term photometric variations in the eclipsing polar HU Aqr, the property of mass transfer and accretion are investigated. The correlation between the brightness state change and the variation of the ingress profile suggests that both the accretion hot spot and the accretion stream are produced instantaneously. The observations clearly show that it is the variation of mass transfer causing the brightness state changes that is a direct evidence of variable mass transfer in a CV. It is shown that it is the local dark-spot activity near the L1 point to cause the change of the mass transfer rather than the activity cycles of the cool secondary star. Our results suggest that the evolution of CVs is more complex than that predicted by the standard model and we should consider the effect of variable mass accretion in nova and dwarf nova outbursts.

scholarly journals Dwarf nova outbursts in intermediate polars

2017 ◽  
Vol 602 ◽  
pp. A102 ◽  
Author(s):  
J.-M. Hameury ◽  
J.-P. Lasota
Keyword(s):  
Magnetic Field ◽  
Mass Transfer ◽  
White Dwarf ◽  
Accretion Disc ◽  
Numerical Code ◽  
Dwarf Nova ◽  
Viscous Instability ◽  
Intermediate Polars ◽  
Nova Outbursts ◽  
The Magnetic Field

Context. The disc instability model (DIM) has been very successful in explaining the dwarf nova outbursts observed in cataclysmic variables. When, as in intermediate polars, the accreting white dwarf is magnetised, the disc is truncated at the magnetospheric radius, but for mass-transfer rates corresponding to the thermal-viscous instability such systems should still exhibit dwarf-nova outbursts. Yet, the majority of intermediate polars, in which the magnetic field is not large enough to completely disrupt the accretion disc, seem to be stable, and the rare observed outbursts, in particular in systems with long orbital periods, are much shorter than normal dwarf-nova outbursts. Aims. We investigate the predictions of the disc instability model for intermediate polars in order to determine which of the observed properties of these systems can be explained by the DIM. Methods. We use our numerical code for the time evolution of accretion discs, modified to include the effects of the magnetic field, with constant or variable mass transfer from the secondary star. Results. We show that intermediate polars have mass transfer low enough and magnetic fields large enough to keep the accretion disc stable on the cold equilibrium branch. We show that the infrequent and short outbursts observed in long-period systems, such as, for example, TV Col, cannot be attributed to the thermal-viscous instability of the accretion disc, but instead have to be triggered by an enhanced mass-transfer from the secondary, or, more likely, by some instability coupling the white dwarf magnetic field with that generated by the magnetorotational instability operating in the accretion disc. Longer outbursts (a few days) could result from the disc instability.

scholarly journals The Theoretical Frequency of Classical Nova Outbursts as a Function of White Dwarf Mass

1990 ◽  
Vol 122 ◽  
pp. 386-387 ◽  
Author(s):  
Michael Politano ◽  
Mario Livio ◽  
James W. Truran ◽  
Ronald F. Webbink
Keyword(s):  
White Dwarf ◽  
Relative Frequency ◽  
Cataclysmic Variables ◽  
Mass Function ◽  
Initial Mass Function ◽  
Classical Novae ◽  
Theoretical Frequency ◽  
Classical Nova ◽  
Nova Outbursts ◽  
Recurrence Frequency

Using the distribution of white dwarf masses in zero-age cataclysmic variables (CVs) calculated by Politano and Webbink (these proceedings), the relative frequency of classical nova outbursts as a function of white dwarf mass is calculated. These results are compared with the results obtained by Truran and Livio (1986), who calculated the same function, but used a distribution of white dwarf masses in CVs calculated from a Salpeter initial mass function and a particular progenitor mass-white dwarf mass relationship for single stars.We wish to calculate the frequency of classical nova outbursts as a function of white dwarf mass. To do this, we require two quantities: 1) the recurrence frequency of classical nova outbursts (i.e., how many outbursts per year) and 2) the white dwarf mass spectrum in classical novae (i.e., number of novae per white dwarf mass). We discuss each of these in turn.

scholarly journals The 12C/13C Ratio as a Tracer of the Evolution of Post Common Envelope Systems and Cataclysmic Variables

1996 ◽  
Vol 158 ◽  
pp. 457-458
Author(s):  
M. J. Sarna ◽  
P. B. Marks ◽  
R. C. Smith
Keyword(s):  
Mass Transfer ◽  
Cataclysmic Variables ◽  
Abundance Ratio ◽  
Roche Lobe ◽  
Mass Star ◽  
Convective Envelope ◽  
Dwarf Stars ◽  
Common Envelope ◽  
Secondary Star ◽  
Nova Outbursts

To provide a direct test of common envelope (CE) evolution which can be easily confirmed by observations, we (Sarna et al. 1995) recently modelled the change in the abundance ratio of 12C/13C on the surface of the lower mass star of a binary during the CE phase. The model is based on the fact that it is probable that the dwarf star accretes material during the CE phase. Since, during the CE phase, the dwarf secondary effectively exists within the atmosphere/envelope of the giant or supergiant primary, the accreted material has the abundances/composition of a giant/supergiant star. The 12C/13C ratio is known to decrease from approximately 90 in dwarf stars (in which the 13CO band at 2.3448 microns is barely visible) to approximately 10 in giants (in which the 13CO band at 2.3448 microns is fairly prominent). Hence, by measuring the 12C/13C ratio in post common envelope binaries (PCEBs) and comparing it to our models we would be able not only to confirm the CE theory but also to determine the amount of mass accreted during the CE phase and hence the initial mass of the dwarf component prior to the CE phase. We also propose an evolutionary scenario in which PCEBs with secondary component mass near 1.0 M⊙ start semi-detached evolution almost immediately after the CE phase. The progenitor system is a wide binary consisting of a 3 M⊙ primary with a 1.0 M⊙ secondary star. The primary evolves to fill its Roche lobe when it has a 0.6 M⊙ C–O core, with two shell burning regions. Such a star has a thick convective envelope, mass transfer is dynamically unstable and a common envelope forms. After the CE phase we are left with a close detached binary consisting of the primary’s core (0.6 M⊙) and the secondary (1.0 M⊙) main sequence star. Shortly afterwards the secondary fills its Roche lobe and mass transfer occurs (Sarna, Marks & Smith 1995). The system now evolves as a semi-detached binary (CV), transferring material to the white dwarf which undergoes nova outbursts. Figs. 1 and 2 show the isotopic ratios of 12C/13C and 16O/17O during the semi-detached evolution. In Fig. 1 the secondary did not accrete any material during CE evolution whilst in Fig. 2 the secondary accreted 0.2M⊙ during the CE stage.

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