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 The White Dwarf Mass and Orbital Period Distributions in Zero-Age Cataclysmic Variables

1990 ◽  
Vol 122 ◽  
pp. 392-393
Author(s):  
M. Politano ◽  
R.F. Webbink
Keyword(s):  
Mass Distribution ◽  
White Dwarf ◽  
White Dwarfs ◽  
Stellar Population ◽  
Cataclysmic Variables ◽  
Cataclysmic Variable ◽  
Solar Mass ◽  
Orbital Periods ◽  
Rapid Mass ◽  
Made In

A zero-age cataclysmic variable (ZACV) we define as a binary system at the onset of interaction as a cataclysmic variable. We present here the results of calculations of the distributions of white dwarf masses and of orbital periods in ZACVs, due to binaries present in a stellar population which has undergone continuous, constant star formation for 1010 years. These results differ from previous work (Politano and Webbink 1988) in that an improved criterion for stability against rapid mass transfer by the secondary to the white dwarf has been used. A brief outline of the method and key assumptions made in this calculation is given in Politano and Webbink (1988).The white dwarf mass distribution of ZACVs (shown in Figure 1) contains two components: systems with helium white dwarfs and systems with C-0 white dwarfs. Systems with helium white dwarfs comprise slightly greater than 50% of all ZACVs. The helium white dwarfs have masses which range from 0.27 to 0.46 solar mass. The C-0 white dwarfs have masses which range from 0.54 solar mass up to the Chandrasekhar mass. (Note: systems with O-Ne-Mg white dwarfs are not distinguished from systems with C-0 white dwarfs in this calculation. Presumably, these O-Ne-Mg systems comprise the upper end of the white dwarf mass distribution.)

On the Statistics of AM Herculis Binaries

1995 ◽  
Vol 12 (2) ◽  
pp. 165-169 ◽  
Author(s):  
Kinwah Wu ◽  
Dayal T. Wickramasinghe ◽  
Jianke Li
Keyword(s):  
Magnetic Field ◽  
Orbital Period ◽  
High Field ◽  
White Dwarfs ◽  
Cataclysmic Variables ◽  
Cataclysmic Variable ◽  
The Difference ◽  
The Magnetic Field ◽  
Very High

AbstractThe magnetic field and orbital period distributions of AM Herculis binaries are investigated. Our study shows that (i) there is a significant lack of very-high-field magnetic white dwarfs in binaries when compared with isolated white dwarfs, and (ii) the difference between the period distributions of AM Herculis binaries and other cataclysmic variable subclasses is statistically significant. These results imply that the evolution and the birth of AM Herculis binaries are different from those of other cataclysmic variables.

scholarly journals Identification of 3XMM J000511.8+634018 as a new polar at Porb = 133.5 min – is it inside or outside the period gap?

2020 ◽  
Vol 637 ◽  
pp. A35
Author(s):  
A. D. Schwope ◽  
H. Worpel ◽  
N. A. Webb ◽  
F. Koliopanos ◽  
S. Guillot
Keyword(s):  
Optical Spectroscopy ◽  
Orbital Period ◽  
Thermal Plasma ◽  
White Dwarf ◽  
Cataclysmic Variables ◽  
Light Curves ◽  
Cataclysmic Variable ◽  
Minimum Period ◽  
X Ray ◽  
Bright Phase

Aims. We aimed to identify the variable X-ray source 3XMM J000511.8+634018, which was serendipitously discovered through routine inspections while the 3XMM catalogue was compiled. Methods. We analysed the archival XMM-Newton observation of the source, obtained BUSCA photometry in three colours, and performed optical spectroscopy with the LBT. These data were supplemented by archival observations from the Zwicky Transient Facility. Results. Based on its optical and X-ray properties, 3XMM J000511.8+634018 is classified as a magnetic cataclysmic variable, or polar. The flux is modulated with a period of 2.22 h (8009.1 ± 0.2 s), which we identify with the orbital period. The bright phases are highly variable in X-ray luminosity from one cycle to the next. The source shows a thermal plasma spectrum typical of polars without evidence of a luminous soft blackbody-like component. It is non-eclipsing and displays one-pole accretion. The X-ray and BUSCA light curves show a stream absorption dip, which suggests an inclination 50° < i <  75°. The phasing of this feature, which occurs at the end of the bright phase, requires a somewhat special accretion geometry with a stream running far around the white dwarf before it is magnetically channelled. The period of this polar falls within the period gap of the cataclysmic variables (2.15−3.18 h), but appears to fall just below the minimum period when only polars are considered.

Variable white dwarfs

2019 ◽  
Vol 15 (S357) ◽  
pp. 107-109
Author(s):  
H. L. Shipman
Keyword(s):  
Present State ◽  
White Dwarf ◽  
White Dwarfs ◽  
Long Term Evolution ◽  
Surface Layers ◽  
Dwarf Stars ◽  
Comprehensive View ◽  
White Dwarf Stars ◽  
Term Evolution

AbstractAsteroseismology of white dwarf stars has led to a number of interesting results pertaining to the long term evolution and present state of white dwarf interiors. I will review recent results and will give a not necessarily comprehensive view of the prospects for further progress in this area. Two – but only two white dwarf stars - have shown the expected cooling as they age. Careful observations of a few white dwarfs with rich pulsational properties reveal interior compositions as well as the thickness of their surface layers. A few very well observed stars have revealed changes in their pulsational spectra which we don’t understand yet.

scholarly journals The Low State Temperature Distribution and First Chemical Abundances of White Dwarfs in Polars

2004 ◽  
Vol 190 ◽  
pp. 2-7
Author(s):  
Edward M. Sion
Keyword(s):  
Temperature Distribution ◽  
White Dwarf ◽  
White Dwarfs ◽  
Chemical Abundance ◽  
Chemical Abundances ◽  
Heating And Cooling ◽  
Cyclotron Emission ◽  
Far Ultraviolet ◽  
Optical Brightness

AbstractDuring the low optical brightness states of AM Her systems (polars) when accretion has declined to a very low value, the underlying magnetic white dwarf photosphere can be modelled without the complication of thermal bremstrahlung and cyclotron emission from the luminous accretion column. The far ultraviolet spectra can be modelled with high gravity Solar composition photospheres. In this way, I present new temperatures and the first chemical abundance estimates for the white dwarfs in three selected polars from the IUE NEWSIPS archive. For the white dwarf in V834 Cen with Teff = 16,000K, Si/H = 0.1 Solar, C/H = 0.5 Solar, for BY Cam, Teff = 17,000K, Si/H = 0.1, C/H = 5 Solar and for RX J1313-32, Teff = 22,000K, Si/H = 0.1 Solar, C/H = 0.1 Solar. The temperature distribution of 24 white dwarfs in polars with known temperatures above and below the period gap is compared with the distribution of the white dwarf temperatures in dwarf novae during quiescence. In both cases, the magnetic white dwarfs in polars are significantly cooler than the non-magnetics. For all CV white dwarfs, magnetic and non-magnetic with Teff < 12,500K, 91% of the objects (10 out of 11) are magnetics in polars. This suggests that long term accretion heating and cooling of white dwarfs in polars differs from the effects of long term accretion in non-magnetic disk accretors.

scholarly journals Pulsating white dwarfs in cataclysmic variables: The marriage of ZZ Cet and dwarf nova

2004 ◽  
Vol 193 ◽  
pp. 382-386 ◽  
Author(s):  
Brian Warner ◽  
Patrick A. Woudt
Keyword(s):  
White Dwarf ◽  
Large Amplitude ◽  
White Dwarfs ◽  
Cataclysmic Variables ◽  
Sloan Digital Sky Survey ◽  
Dwarf Novae ◽  
Dwarf Nova ◽  
Sky Survey

AbstractThere are now four dwarf novae known with white dwarf primaries that show large amplitude non-radial oscillations of the kind seen in ZZ Cet stars. We compare the properties of these stars and point out that by the end of the Sloan Digital Sky Survey more than 30 should be known.

scholarly journals Search For Cool White Dwarf Pulsators

2000 ◽  
Vol 176 ◽  
pp. 525-526
Author(s):  
Atsuko Nitta ◽  
A. Mukadam ◽  
D. E. Winget ◽  
A. Kanaan ◽  
S. J. Kleinman ◽  
...  
Keyword(s):  
Lower Limit ◽  
White Dwarf ◽  
White Dwarfs ◽  
Galactic Disk ◽  
Chemical Compositions ◽  
Physical Processes ◽  
Effective Temperatures

AbstractWe are searching for pulsations in cool (< 6000 K) white dwarfs (WDs), hoping to apply asteroseismological techniques to improve our understanding of their structure and the physical processes inside them. This information is important as we use cool WDs to estimate the lower limit of the age of the Galactic disk. Within a spectroscopic and photometric survey of 110 cool WDs by Bergeron, Ruiz, & Legget, we find 28 candidates with appropriate effective temperatures, masses, and chemical compositions for possible pulsations in nonradial g modes with periods similar to those we observe in DAVs. So far, we have observed 4 candidates, but have found no evidence of large variation.

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