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 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 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 On the Evolution of the Nova-like Variable AE Aquarii

2004 ◽  
Vol 190 ◽  
pp. 300-306
Author(s):  
P. J. Meintjes
Keyword(s):  
Mass Transfer ◽  
Orbital Period ◽  
White Dwarf ◽  
Time Scale ◽  
Critical Mass ◽  
Current Phase ◽  
Thermal Activity ◽  
Secondary Star ◽  
Wind Theory ◽  
Mass Ejection

AbstractIt is shown here that the peculiar properties of AE Aqr can can be accounted for if the mass transfer from an evolved 0.7M⊙ secondary K4-5 star (qi ≈ 0.8, i.e. < 1) initiated when the orbital period of the binary was Porb,i ≈ 8.5 hours and the white dwarf period P*,i ≈ 1 hour. This resulted in a significant amount of orbital angular momentum being accreted by the white dwarf in an initial discless spin-up phase towards P* ≈ 0.1 Porb,i. This destabilized the mass transfer, resulting in a run-away mass transfer from the secondary that lasted for approximately 104 years, with the orbital period evolving to Porb ≈ 11 hours until a critical mass ratio of qcrit = 0.73 had been reached. In this phase the mass transfer from the secondary occurred at a rapid rate of approximately Ṁ2 ≈ 1020 g s-1, resulting in an accretion disc which spun-up the white dwarf to a period of approximately P* ≈ 33 s. For all q ≤ qcrit = 0.73 the mass transfer proceeded on the thermal time scale of the secondary star, i.e. at a much slower rate, resulting in the binary converging and forcing AE Aqr into the propeller phase. Applying stellar wind theory, this allow an estimate of the polar magnetic field of the secondary star, which is of the order of B° ≈ (1600 – 2000) G. It has been shown here that the duration of mass transfer phase q = qcrit → 0.67 (now) lasted for approximately tṀ2 ~ 107 years, similar to the spin-down time scale of the white dwarf, tsd = P*/P* ≈ 107 years. The propeller ejection of matter in the current phase results in the dissipation of mhd power of Lmhd ≈ 1034 erg s-1, probably channeled into mass ejection and non-thermal activity. This explains the non-thermal outbursts that are observed in radio wavelengths, and occasionally also in TeV energies, from AE Aqr.

Accretion simulations of Eta Carinae and implications to massive binaries

2018 ◽  
Vol 14 (S346) ◽  
pp. 93-97
Author(s):  
Amit Kashi
Keyword(s):  
Mass Transfer ◽  
High Resolution ◽  
Massive Stars ◽  
High Mass ◽  
Eccentric Orbit ◽  
Mass Model ◽  
X Ray ◽  
Eta Carinae ◽  
Secondary Star ◽  
Hydrodynamical Simulations

AbstractUsing high resolution 3D hydrodynamical simulations we quantify the amount of mass accreted onto the secondary star of the binary system η Carinae during periastron passage on its highly eccentric orbit. The accreted mass is responsible for the spectroscopic event occurring every orbit close to periastron passage, during which many lines vary and the x-ray emission associated with the destruction wind collision structure declines. The system is mainly known for its giant eruptions that occurred in the nineteenth century. The high mass model of the system, M1=170M⊙ and M2=80M⊙, gives Macc≍ 3×10−6M⊙ compatible with the amount required for explaining the reduction in secondary ionization photons during the spectroscopic event, and also matches its observed duration. As accretion occurs now, it surely occurred during the giant eruptions. This implies that mass transfer can have a huge influence on the evolution of massive stars.

scholarly journals Effective Growth Rate of White Dwarf Mass in Nova Outbursts

1990 ◽  
Vol 122 ◽  
pp. 390-391
Author(s):  
Mariko Kato ◽  
Izumi Hachisu
Keyword(s):  
Mass Transfer ◽  
Growth Rate ◽  
Mass Loss ◽  
White Dwarf ◽  
Transfer Rate ◽  
Mass Transfer Rate ◽  
Net Growth Rate ◽  
Chandrasekhar Limit ◽  
Nova Outbursts ◽  
Effective Growth

AbstractWe have obtained the effective growth rate of white dwarf masses which are suffering mass loss during both hydrogen and helium nova outbursts. If the mass transfer rate from the companion is smaller than 10−7 M⊙/yr, the net growth rate is reduced to less than one tenth of the mass transfer rate from the companion star. It is suggested that the white dwarf mass is hard to grow to the Chandrasekhar mass unless its initial mass is very close to the Chandrasekhar limit.

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 A Modern View of the Dwarf Nova Z Chamaeleontis

1987 ◽  
Vol 93 ◽  
pp. 507-509
Author(s):  
R.A. Wade
Keyword(s):  
Mass Transfer ◽  
White Dwarf ◽  
Dwarf Nova ◽  
Secondary Star ◽  
Modern View ◽  
Cataclysmic Binaries ◽  
Space Motion ◽  
Period System

AbstractSome recent photometric and spectroscopic results for this “ultrashort” period system are summarized, and several straightforward consequences of these results for our understanding of the evolution of cataclysmic binaries are pointed out: The space motion of Z Cha is characteristic of the old disk population. The white dwarf cannot be composed primarily of He, unless it grew by accretion by at least 20%. The inferred masses of the component stars, combined with the usual gravitational quadrupole formula, probably do not suffice to explain the inferred rate of mass transfer, even in quiescence. The secondary star does not lie on the computed evolutionary tracks in the period - mass diagram of Paczynski and Sienkiewicz.

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 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.

Mass transfer in double white dwarf binaries

2008 ◽  
Vol 51 (10-12) ◽  
pp. 878-883 ◽  
Author(s):  
Juhan Frank
Keyword(s):  
Mass Transfer ◽  
White Dwarf
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