scholarly journals High resolution SPH simulations of merging white dwarfs binary systems

2008 ◽  
Author(s):  
Pablo Loren
Keyword(s):  
High Resolution ◽  
White Dwarfs ◽  
Binary Systems

scholarly journals High Resolution Optical Spectra of 120 White Dwarfs

1989 ◽  
Vol 114 ◽  
pp. 524-524 ◽  
Author(s):  
David Tytler ◽  
Eric Rubenstein
Keyword(s):  
High Resolution ◽  
White Dwarfs ◽  
Binary Systems ◽  
High Amplitude ◽  
Optical Spectra ◽  
Absorption Lines ◽  
Type I ◽  
High Quality ◽  
Velocity Variations

AbstractHigh quality optical spectra of 120 white dwarfs have been obtained to search for double degenerate systems, some of which might become type I supernovae. No systems with high amplitude velocity variations have been found. However several exceptionally cool DA white dwarfs have been found to show weak Helium absorption lines, and four stars have split H-alpha line cores indicative of binary systems.

scholarly journals The Search for Close Binary Evolved Stars

1989 ◽  
Vol 114 ◽  
pp. 408-412
Author(s):  
Rex A. Saffer ◽  
James Liebert
Keyword(s):  
Binary System ◽  
White Dwarf ◽  
White Dwarfs ◽  
Binary Systems ◽  
Close Binary ◽  
Brown Dwarf ◽  
Null Results ◽  
Spectroscopic Observations ◽  
Evolved Stars ◽  
Short Period

AbstractWe report on a search for short-period binary systems composed of pairs of evolved stars. The search is being carried out concurrently with a program to characterize the kinematical properties of two different samples of stars. Each sample has produced one close binary candidate for which further spectroscopic observations are planned. We also recapitulate the discovery of a close detached binary system composed of two cool DA white dwarfs, and we discuss the null results of Hα observations of the suspected white dwarf/brown dwarf system G 29–38.

Accretion-Induced Collapse of Old White Dwarfs

1987 ◽  
Vol 93 ◽  
pp. 665-669
Author(s):  
J. Isern ◽  
R. Canal ◽  
M. Hernanz ◽  
J. Labay
Keyword(s):  
Neutron Stars ◽  
Gravitational Collapse ◽  
White Dwarfs ◽  
Binary Systems ◽  
Observational Evidence ◽  
Dynamical Instability ◽  
Thermonuclear Explosion

AbstractThere is observational evidence of the presence of young neutron stars in old binary systems. A likely explanation is that those neutron stars were produced in the collapse of old CO white dwarfs. We show how mass accretion on initially solid white dwarfs can leave central solid cores when dynamical instability sets in and we study the different effects of the existence of such cores on the outcome of the competition between thermonuclear explosion and gravitational collapse.

scholarly journals Nucleosynthesis During Nova Explosions and Grain Formations in Ejected Envelopes

1979 ◽  
Vol 53 ◽  
pp. 533-533
Author(s):  
Masayuki Y. Fujimoto
Keyword(s):  
General Theory ◽  
White Dwarf ◽  
White Dwarfs ◽  
Binary Systems ◽  
Thermal Emission ◽  
Finite Amplitude ◽  
Close Binary ◽  
Close Binary Systems

Recent observations have revealed the existence of infrared brightening in some nova explosions, and its absence in others. These infrared excesses are ascribed to thermal emission from grains which are considered to consist of graphite. Such nova explosions are widely accepted to be triggered by hydrogen shell-flashes on the surface of white dwarfs which accrete matter in close binary systems. As for the hydrogen shell-flash, recently, a general theory applicable even to the case of finite amplitude has been developed. According to this theory, the progress of a shell-flash is determined only by the mass of the white dwarf MWD and the mass of the accreted hydrogen-rich envelope ΔMH.

scholarly journals m = 1 Oscillations of Accretion Disks in Close Binary Systems

1997 ◽  
Vol 163 ◽  
pp. 777-778
Author(s):  
Atsuo T. Okazaki
Keyword(s):  
Accretion Disks ◽  
Fundamental Mode ◽  
White Dwarfs ◽  
Binary Systems ◽  
Close Binary ◽  
Dimensional Structure ◽  
Two Dimensional ◽  
Close Binary Systems

AbstractWe examine the two-dimensional structure of m = 1 modes in disks around white dwarfs in close binary systems. We find that the odd modes (warping modes) as well as even modes (eccentric modes) are confined to the outermost part of the disk. The period of the fundamental mode is of a few percent of the binary period, and is insensitive to the parity of the mode. These modes naturally explain the superhump periods of SU UMa stars.

scholarly journals A ROSAT survey of hot DA white dwarfs in non-interacting binary systems

1994 ◽  
Vol 270 (3) ◽  
pp. 499-515 ◽  
Author(s):  
M. A. Barstow ◽  
J. B. Holberg ◽  
T. A. Fleming ◽  
M. C. Marsh ◽  
D. Koester ◽  
...  
Keyword(s):  
White Dwarfs ◽  
Binary Systems

scholarly journals EUVE J0825-16.3 and EUVE J1501-43.6: Two dMe Double–Lined Spectroscopic Binaries

2006 ◽  
Vol 2 (S240) ◽  
pp. 690-696
Author(s):  
D. Montes ◽  
I. Crespo-Chacón ◽  
M.C. Gálvez ◽  
M.J. Fernández-Figueroa
Keyword(s):  
High Resolution ◽  
Orbital Period ◽  
Binary Systems ◽  
Cross Correlation ◽  
Rotational Velocity ◽  
Spectroscopic Binaries ◽  
Balmer Lines ◽  
First Time ◽  
Orbital Solution ◽  
Similar Intensity

AbstractHigh-resolution echelle spectroscopic observations taken with the FEROS spectrograph at the ESO 2.2-m telescope confirm the binary nature of the dMe stars EUVE J0825−16.3 and EUVE J1501−43.6, previously reported by Christian & Mathioudakis (2002). In these binary systems, emission of similar intensity from both components is detected in the Na i D1 & D2, He i D3, Ca II H&K, Ca II IRT and Balmer lines. We have determined precise radial velocities by cross-correlation with radial velocity standard stars, which have allowed us to obtain for the first time the orbital solution of these systems. Both binaries consist of two nearly equal M0V components with an orbital period shorter than 3.5 days. We have analyzed the behaviour of the chromospheric activity indicators (variability and possible flares). In addition, we have determined its rotational velocity and kinematics.

Speckle Interferometry. III. High-Resolution Measurements of Twelve Close Binary Systems

1974 ◽  
Vol 194 ◽  
pp. L147 ◽  
Author(s):  
A. Labeyrie ◽  
D. Bonneau ◽  
R. V. Stachnik ◽  
D. Y. Gezari
Keyword(s):  
High Resolution ◽  
Binary Systems ◽  
Speckle Interferometry ◽  
Close Binary ◽  
Close Binary Systems

scholarly journals White Dwarfs in Cataclysmic Binaries

1979 ◽  
Vol 53 ◽  
pp. 417-425 ◽  
Author(s):  
Brian Warner
Keyword(s):  
Direct Measurement ◽  
White Dwarf ◽  
Proper Motion ◽  
White Dwarfs ◽  
Binary Systems ◽  
Fundamental Property ◽  
Wide Binary ◽  
Trigonometric Parallax ◽  
Select Group ◽  
Cataclysmic Binaries

For isolated stars, identification as a white dwarf may be effected in several ways. The fundamental property of abnormally low luminosity can be detected through direct measurement of trigonometric parallax or indirectly through large proper motion (accompanied by appropriate photometric properties). The presence of greatly pressure broadened absorption lines is another unambiguous criterion. Rapid light oscillations of the kind reviewed by Robinson are another hallmark of a select group of white dwarfs. Any or all of these criteria may be used to classify a star as a white dwarf and in general can be applied to members of wide binary systems.

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