The chemical composition of the white dwarfs in cataclysmic variable systems which produce novae

1988 ◽  
pp. 234-235 ◽  
Author(s):  
Warren M. Sparks ◽  
Sumner G. Starrfield ◽  
James W. Truran ◽  
G. Siegfried Kutter
Keyword(s):  
Chemical Composition ◽  
White Dwarfs ◽  
Cataclysmic Variable

scholarly journals The Chemical Composition of the White Dwarfs in Cataclysmic Variable Systems which Produce Novae

1988 ◽  
Vol 108 ◽  
pp. 234-235
Author(s):  
Warren M. Sparks ◽  
Sumner G. Starrfield ◽  
James W. Truran ◽  
G. Siegfried Kutter
Keyword(s):  
Chemical Composition ◽  
White Dwarf ◽  
White Dwarfs ◽  
Positive Answer ◽  
Cataclysmic Variable ◽  
Nuclear Abundance

Recently a number of studies have been published on the nuclear abundance of nova ejecta, as summarized by Truran and Livio (1986). H is always underabundant (compared to solar) and He is overabundant except for the cases where the heavier elements are far overabundant. The abundances of C, N, and O range from nearly solar to highly overabundant. A few novae are very rich in Ne and Mg as well as O, which has led to the discovery that these novae occur on O/Ne/Mg white dwarfs (Williams, et al., 1985). We will assume that the abundances are an accurate and consistently determined set of data for our purposes. The nova ejecta is a combination of original white dwarf material, remnant material, remaining on the white dwarf from the previous outburst, and accreted material, all of which has undergone thermonuclear processing during the outburst. The question we address here is “Can we untangle the observational abundances to determine the contributions of each source?” A positive answer would allow us to tell whether the white dwarf’s mass is increasing or decreasing and thus have implications on the accreting white dwarf model for a SNI.

The Chemical Composition of White Dwarfs as a Test of Convective Efficiency during Core Helium Burning

2003 ◽  
Vol 583 (2) ◽  
pp. 878-884 ◽  
Author(s):  
Oscar Straniero ◽  
Inmaculada Dominguez ◽  
Gianluca Imbriani ◽  
Luciano Piersanti
Keyword(s):  
Chemical Composition ◽  
White Dwarfs ◽  
Helium Burning

scholarly journals 19. Convection Zones and Coronae of White Dwarfs

1971 ◽  
Vol 42 ◽  
pp. 130-135 ◽  
Author(s):  
K. H. Böhm ◽  
J. Cassinelli
Keyword(s):  
Chemical Composition ◽  
Temperature Gradient ◽  
White Dwarf ◽  
White Dwarfs ◽  
Convection Zone ◽  
Adiabatic Temperature ◽  
Turbulent Convection ◽  
Cool White Dwarfs ◽  
Adiabatic Temperature Gradient

Outer convection zones of white dwarfs in the range 5800 K ≤ Teff ≤ 30000 K have been studied assuming that they have the same chemical composition as determined by Weidemann (1960) for van Maanen 2. Convection is important in all these stars. In white dwarfs Teff < 8000 K the adiabatic temperature gradient is strongly influenced by the pressure ionization of H, HeI and HeII which occurs within the convection zone. Partial degeneracy is also important.Convective velocities are very small for cool white dwarfs but they reach considerable values for hotter objects. For a white dwarf of Teff = 30000 K a velocity of 6.05 km/sec and an acoustic flux (generated by the turbulent convection) of 1.5 × 1011 erg cm−2 sec−1 is reached. The formation of white dwarf coronae is briefly discussed.

scholarly journals The chemical structure of the hot pulsating DB white dwarf KIC 08626021 from asteroseismology

2019 ◽  
Vol 15 (S357) ◽  
pp. 119-122
Author(s):  
S. Charpinet ◽  
P. Brassard ◽  
N. Giammichele ◽  
Gilles Fontaine
Keyword(s):  
Chemical Composition ◽  
White Dwarf ◽  
White Dwarfs ◽  
Chemical Structure ◽  
Neutrino Emission ◽  
Energy Losses ◽  
Seismic Model ◽  
Limited Impact ◽  
Static Models

AbstractGiammichele et al. (2018) proposed a full determination, largely independent of evolution calculations, of the chemical composition and stratification inside the hot pulsating DB white dwarf KIC 08626021. However, Timmes et al. (2018) pointed out that neglecting the effects of neutrino cooling, such as in the static models used in Giammichele et al. study, could impact significantly the derived seismic solution and compromise conclusions drawn upon it. Here we present a reanalysis of KIC 08626021, using improved static models which now incorporate more realistic luminosity profiles that reflect the still significant energy losses induced by neutrino emission mechanisms in hot DB white dwarfs. We show that this effect has only a limited impact on the derived seismic model properties and, more importantly, that all the conclusions brought by Giammichele et al. (2018) remain entirely valid.

scholarly journals The Effective Temperature Distribution Function of Cataclysmic Variable White Dwarfs

1987 ◽  
Vol 93 ◽  
pp. 47-51
Author(s):  
E.M. Sion
Keyword(s):  
Distribution Function ◽  
Temperature Distribution ◽  
Orbital Period ◽  
White Dwarf ◽  
White Dwarfs ◽  
Cataclysmic Variables ◽  
Cataclysmic Variable ◽  
Term Evolution ◽  
Effective Temperatures

AbstractWith the recent detection of direct white dwarf photospheric radiation from certain cataclysmic variables in quiescent (low accretion) states, important implications and clues about the nature and long-term evolution of cataclysmic variables can emerge from an analysis of their physical properties. Detection of the underlying white dwarfs has led to a preliminary empirical CV white dwarf temperature distribution function and, in a few cases, the first detailed look at a freshly accreted while dwarf photosphere. The effective temperatures of CV white dwarfs plotted versus orbital period for each type of CV appears to reveal a tendency for the cooler white dwarf primaries to reside in the shorter period systems. Possible implications are briefly discussed.

scholarly journals 11. Effective Temperatures of White Dwarfs

1971 ◽  
Vol 42 ◽  
pp. 67-76 ◽  
Author(s):  
J. B. Oke ◽  
H. L. Shipman
Keyword(s):  
Chemical Composition ◽  
White Dwarf ◽  
White Dwarfs ◽  
Dwarf Stars ◽  
Evolved Stars ◽  
White Dwarf Stars ◽  
Effective Temperatures ◽  
Highly Evolved

White dwarf stars are among the most challenging and interesting objects which can be studied. Because they represent the interiors of highly-evolved stars, the chemical composition can be enormously variable from object to object. Furthermore, because of the very large gravities, the composition of the atmosphere may be very different from that in the interior. The theory of the degenerate interior provides a relation among mass, radius and chemical composition. Since temperatures, effective gravities, and redshifts can, for certain stars, provide further relations between mass and radius, one can hope to make checks on the theory which are not possible with ordinary stars.

scholarly journals Effective temperatures of cataclysmic-variable white dwarfs as a probe of their evolution

2016 ◽  
Vol 466 (3) ◽  
pp. 2855-2878 ◽  
Author(s):  
A. F. Pala ◽  
B. T. Gänsicke ◽  
D. Townsley ◽  
D. Boyd ◽  
M. J. Cook ◽  
...  
Keyword(s):  
White Dwarfs ◽  
Cataclysmic Variable ◽  
Effective Temperatures

scholarly journals Optical detection of the rapidly spinning white dwarf in V1460 Her

2021 ◽  
Author(s):  
Ingrid Pelisoli ◽  
R T Marsh ◽  
R P Ashley ◽  
Pasi Hakala ◽  
A Aungwerojwit ◽  
...  
Keyword(s):  
White Dwarf ◽  
White Dwarfs ◽  
Binary Systems ◽  
Hubble Space Telescope ◽  
Cataclysmic Variable ◽  
Optical Photometry ◽  
Arrival Times ◽  
Precise Ephemeris ◽  
History Of

Abstract Accreting magnetic white dwarfs offer an opportunity to understand the interplay between spin-up and spin-down torques in binary systems. Monitoring of the white dwarf spin may reveal whether the white dwarf spin is currently in a state of near-equilibrium, or of uni-directional evolution towards longer or shorter periods, reflecting the recent history of the system and providing constraints for evolutionary models. This makes the monitoring of the spin history of magnetic white dwarfs of high interest. In this paper we report the results of a campaign of follow-up optical photometry to detect and track the 39 sec white dwarf spin pulses recently discovered in Hubble Space Telescope data of the cataclysmic variable V1460 Her. We find the spin pulsations to be present in g-band photometry at a typical amplitude of 0.4 per cent. Under favourable observing conditions, the spin signal is detectable using 2-meter class telescopes. We measured pulse-arrival times for all our observations, which allowed us to derive a precise ephemeris for the white dwarf spin. We have also derived an orbital modulation correction that can be applied to the measurements. With our limited baseline of just over four years, we detect no evidence yet for spin-up or spin-down of the white dwarf, obtaining a lower limit of $|P/\dot{P}| &gt; 4\times 10^{7}$ years, which is already 4 to 8 times longer than the timescales measured in two other cataclysmic variable systems containing rapidly rotating white dwarfs, AE Aqr and AR Sco.

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