Helium and Carbon‐Oxygen White Dwarfs in Close Binaries

1997 ◽  
Vol 475 (1) ◽  
pp. 291-299 ◽  
Author(s):  
Icko Iben, Jr. ◽  
Alexander V. Tutukov ◽  
Lev R. Yungelson
Keyword(s):  
White Dwarfs ◽  
Close Binaries

scholarly journals AM Herculis Binaries

1996 ◽  
Vol 165 ◽  
pp. 403-414 ◽  
Author(s):  
K. Beuermann
Keyword(s):  
White Dwarf ◽  
White Dwarfs ◽  
Close Binaries ◽  
Physical Processes ◽  
X Ray ◽  
Sky Survey

AM Herculis binaries contain mass accreting magnetic white dwarfs which appear as bright X-ray sources in the ROSAT All Sky Survey. About 52 systems are presently known which allow detailed studies of the evolution of magnetic close binaries and of fundamental plasma-physical processes in the accretion region on the white dwarf.

scholarly journals Family links between Planetary Nebulae nuclei and cataclysmic variables, binary white dwarfs, R CrB stars, and SNe IA

1997 ◽  
Vol 180 ◽  
pp. 85-90
Author(s):  
L.R. Yungelson ◽  
A.V. Tutukov
Keyword(s):  
White Dwarfs ◽  
Cataclysmic Variables ◽  
Planetary Nebulae ◽  
Close Binaries ◽  
Symbiotic Stars

We analyse the population of PNe and links between binary PNNi and stars which are in the later evolutionary stages. In a model which assumes that all stars are born in binaries, about 16% of PN result from ejection of common envelopes in close binaries, 85% of single PNNi are formed by merger of components of binaries. In the model, 5% of PNNi may be precataclysmic binaries, 5% may be precursors of symbiotic stars, 0.4% may be pre-SN Ia, 0.1% - precursors of hydrogen-deficient giants. About 0.1% of all PNe may be hydrogen-deficient.

scholarly journals Birth of the ELMs: a ZTF survey for evolved cataclysmic variables turning into extremely low-mass white dwarfs

2021 ◽  
Author(s):  
Kareem El-Badry ◽  
Hans-Walter Rix ◽  
Eliot Quataert ◽  
Thomas Kupfer ◽  
Ken J Shen
Keyword(s):  
Mass Transfer ◽  
White Dwarfs ◽  
Main Sequence ◽  
Cataclysmic Variables ◽  
Close Binaries ◽  
Convective Envelope ◽  
Compact Binary ◽  
Show Evidence ◽  
Low Mass ◽  
Hubble Time

Abstract We present a systematic survey for mass-transferring and recently-detached cataclysmic variables (CVs) with evolved secondaries, which are progenitors of extremely low mass white dwarfs (ELM WDs), AM CVn systems, and detached ultracompact binaries. We select targets below the main sequence in the Gaia colour-magnitude diagram with ZTF light curves showing large-amplitude ellipsoidal variability and orbital period Porb < 6 hr. This yields 51 candidates brighter than G = 18, of which we have obtained many-epoch spectra for 21. We confirm all 21 to be completely– or nearly–Roche lobe filling close binaries. 13 show evidence of ongoing mass transfer, which has likely just ceased in the other 8. Most of the secondaries are hotter than any previously known CV donors, with temperatures 4700 < Teff/K < 8000. Remarkably, all secondaries with $T_{\rm eff} \gtrsim 7000\, \rm K$ appear to be detached, while all cooler secondaries are still mass-transferring. This transition likely marks the temperature where magnetic braking becomes inefficient due to loss of the donor’s convective envelope. Most of the proto-WD secondaries have masses near 0.15 M⊙; their companions have masses near 0.8 M⊙. We infer a space density of $\sim 60\, \rm kpc^{-3}$, roughly 80 times lower than that of normal CVs and three times lower than that of ELM WDs. The implied Galactic birth rate, $\mathcal {R}\sim 60\, \rm Myr^{-1}$, is half that of AM CVn binaries. Most systems are well-described by MESA models for CVs in which mass transfer begins only as the donor leaves the main sequence. All are predicted to reach minimum periods 5 ≲ Porb/min ≲ 30 within a Hubble time, where they will become AM CVn binaries or merge. This sample triples the known evolved CV population and offers broad opportunities for improving understanding of the compact binary population.

scholarly journals The Origin and Evolution of Novae

1990 ◽  
Vol 122 ◽  
pp. 325-341
Author(s):  
A.V. Tutukov ◽  
L.R. Yungelson
Keyword(s):  
Time Scales ◽  
White Dwarfs ◽  
Initial Mass ◽  
Close Binaries ◽  
Recurrence Time ◽  
Origin And Evolution ◽  
Cataclysmic Binaries ◽  
Mass Ratios

AbstractThe cataclysmic binaries are products of the nonconservative evolution of close binaries with large initial mass ratios of components. The accretors in cataclysmic binaries can be helium or carbon-oxygen or oxygen-neon-magnesium white dwarfs. Their annual birthrates are ~0.005, ~0.005, and ~0.00005 respectively. In one-zone approximation of a thin accreting shell we estimate the critical masses of hydrogen and helium shells and recurrence time scales of thermonuclear runaways.

scholarly journals A VLA Survey of Magnetic Cataclysmic Variable Stars

2004 ◽  
Vol 194 ◽  
pp. 267-267
Author(s):  
Сandace Gray ◽  
Paul A. Mason
Keyword(s):  
Accretion Disks ◽  
White Dwarfs ◽  
Cataclysmic Variables ◽  
Variable Stars ◽  
Close Binaries ◽  
Lagrangian Point ◽  
Lower Field ◽  
Intermediate Polars ◽  
Binary Orbit ◽  
Magnetic Poles

Cataclysmic Variables (CVs) are close binaries containing a white dwarf primary and a Rochelobe filling red dwarf secondary. In magnetic CVs (MCVs) the white dwarfs have magnetic fields that are sufficiently strong (106 – 108 Gauss) to direct the accretion flow onto the surface of the primary. MCVs are divided into the lower field intermediate polars (IPs) and the higher field polars. Typically, IPs have accretion disks that are disrupted in the center and magnetically channelled flow onto the poles. Polars are diskless, an accretion stream flowing from the inner Lagrangian point impacts directly onto one or both magnetic poles. In addition, polars tend to have white dwarfs which rotate in synchronism with the binary orbit, while IPs have white dwarfs which rotate faster than the binary period. There are a few rare exceptions to this characterization, such as the slightly asynchronous polars and the stream-fed IPs.

scholarly journals A Limit on the Space Density of Short-Period Binary White Dwarfs

1989 ◽  
Vol 114 ◽  
pp. 492-497
Author(s):  
Edward L. Robinson ◽  
Allen W. Shafter
Keyword(s):  
Orbital Period ◽  
Binary Stars ◽  
White Dwarfs ◽  
Main Sequence ◽  
Close Binaries ◽  
Main Sequence Stars ◽  
Space Density ◽  
Short Period ◽  
Hot Subdwarfs ◽  
Orbital Periods

We infer that detached binary white dwarfs with orbital periods of a few hours exist because we observe both their progenitors and their descendents. The binary LB 3459 has an orbital period of 6.3 hr and contains a pair of hot subdwarfs that will eventually cool to become white dwarfs (Kilkenny, Hill, and Penfold 1981). L870-2 is a pair of white dwarfs and, given enough time, its 1.55 d orbital period will decay to shorter periods (Saffer, Liebert, and Olszewski 1988). GP Com, AM CVn, V803 Cen, and PG1346+082 are interacting binary white dwarfs with orbital periods between 1051 s for AM CVn and 46.5 min for GP Com (Nather, Robinson, and Stover 1981; Solheim et al. 1984; Wood et al. 1987; O’Donoghue and Kilkenny 1988). These ultrashort period systems must be descendents of detached pairs of white dwarfs. We also expect short-period binary white dwarfs to exist for theoretical reasons. All calculations of the evolution of binary stars show that main-sequence binaries can evolve to binary white dwarfs (e.g., Iben and Tutukov 1984). Among Population I stars, 1/2 to 2/3 of all main-sequence stars are binaries and about 20% of these binaries should become double white dwarfs with short orbital periods (Abt 1983, Iben and Tutukov 1986). Thus, about 1/10 of all white dwarfs could be close binaries (Paczynski 1985). Nevertheless, no detached binary white dwarfs with extremely short periods have yet been found.

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