scholarly journals The Spin Periods of Magnetic Cataclysmic Variables

2004 ◽  
Vol 190 ◽  
pp. 216-229 ◽  
Author(s):  
A. J. Norton ◽  
R. V. Somerscales ◽  
G. A. Wynn
Keyword(s):  
Orbital Period ◽  
Magnetic Moment ◽  
White Dwarf ◽  
Magnetic Moments ◽  
Cataclysmic Variables ◽  
Intermediate Polars ◽  
Magnetic Cataclysmic Variables ◽  
Remarkable Agreement

AbstractWe have used a model of magnetic accretion to investigate the rotational equilibria of magnetic cataclysmic variables (MCVs). This has enabled us to derive a set of equilibrium spin periods as a function of orbital period and magnetic moment which we use to estimate the magnetic moments of all known intermediate polars. We further show how these equilibrium spin periods relate to the polar synchronisation condition and use these results to calculate the theoretical histogram describing the distribution of magnetic CVs as a function of Pspin/Porb. We demonstrate that this is in remarkable agreement with the observed distribution assuming that the number of systems as a function of white dwarf magnetic moment is distributed according to .

scholarly journals Multiple Time Scales in Cataclysmic Variables: Observations Vs. Mathematical Models

1998 ◽  
Vol 11 (1) ◽  
pp. 375-375
Author(s):  
I.L. Andronov
Keyword(s):  
White Dwarf ◽  
Cataclysmic Variables ◽  
Theoretical Models ◽  
Magnetic Activity ◽  
Multiple Time Scales ◽  
State Transitions ◽  
Multiple Time ◽  
Intermediate Polars ◽  
Magnetic Cataclysmic Variables ◽  
The Magnetic Field

Theoretical models and observational evidence for various processes in magnetic cataclysmic variables are briefly reviewed. Among them: modulation of the accretion rate by the magnetic field of the white dwarf; excitation of the orientation change of the magnetic axis of the white dwarf with respect to the secondary; structure of the accretion column and its instability; mass and angular momentum transfer; magnetic activity of the secondary; high/low luminosity state transitions; QPO’s, ”shot noise” and ”red noise” in polars, intermediate polars and nova-like objects.

scholarly journals Accretion in Magnetic Cataclysmic Variables

1987 ◽  
Vol 93 ◽  
pp. 583-590 ◽  
Author(s):  
J.M. Hameury ◽  
A.R. King ◽  
J.P. Lasota ◽  
H. Ritter
Keyword(s):  
Magnetic Moment ◽  
Cataclysmic Variables ◽  
Accretion Discs ◽  
Single Class ◽  
Magnetic Systems ◽  
Period Distribution ◽  
Moment Distribution ◽  
Order Of Magnitude ◽  
Intermediate Polars ◽  
Magnetic Cataclysmic Variables

AbstractWe discuss the arguments in favour of the suggestion that polars (AM Her systems) and intermediate polars (IP’s) have magnetic fields of the same order of magnitude, and form one single class of objects. The period distribution of magnetic cataclysmic variables is well explained if they evolve the same way as non magnetic systems, IP’s becoming AM Her systems after crossing the gap. We discuss some consequences of the limited magnetic moment distribution (1033 ≤ μ ≤ 1034 G cm−3) in magnetic CV’s, in particular for the existence of accretion discs in those systems.

scholarly journals VY Sculptoris stars are Magnetic Cataclysmic Variables

2004 ◽  
Vol 190 ◽  
pp. 46-52 ◽  
Author(s):  
Jean-Pierre Lasota ◽  
Jean-Marie Hameury
Keyword(s):  
Mass Transfer ◽  
Transfer Rate ◽  
Magnetic Moments ◽  
Mass Transfer Rate ◽  
Cataclysmic Variables ◽  
Accretion Disc ◽  
Intermediate States ◽  
Intermediate Polars ◽  
Magnetic Cataclysmic Variables ◽  
Evolutionary Aspects

AbstractWe show that VY Scl stars must be magnetized in order to account for the absence of outbursts during their low and intermediate states. Absence of outbursts during low states requires only rather low magnetic moments but in systems in which the drops and rises of luminosity are slower than it takes for the accretion disc to adjust viscously to the variation in mass-transfer rate preventing outbursts require magnetic moments of Intermediate Polars. We discuss some evolutionary aspects of this conclusion.

scholarly journals The EUV Excess in Magnetic Cataclysmic Variables

1996 ◽  
Vol 152 ◽  
pp. 325-329
Author(s):  
John K. Warren ◽  
Koji Mukai
Keyword(s):  
Magnetic Field ◽  
Orbital Period ◽  
White Dwarf ◽  
Preliminary Analysis ◽  
Cataclysmic Variables ◽  
X Rays ◽  
System Parameters ◽  
Magnetic Capture ◽  
Magnetic Cataclysmic Variables ◽  
Capture Radius

We present preliminary analysis of EUVE pointed data of 8 magnetic cataclysmic variables. Blackbody temperatures, luminosities, and interstellar columns have been better constrained. Using these luminosities we look for correlations between the EUV excess (over optical and hard X-rays) and various system parameters. While it appears there is no correlation between the EUV excess and the system inclination and orbital period, correlations are suggested between the EUV excess and the longitude of the accretion spot, the colatitude of the accretion spot, the white dwarf magnetic field, and the magnetic capture radius.

scholarly journals Extreme Ultraviolet Spectroscopy of Magnetic Cataclysmic Variables

1996 ◽  
Vol 152 ◽  
pp. 309-316
Author(s):  
Frits Paerels ◽  
Min Young Hur ◽  
Christopher W. Mauche
Keyword(s):  
High Resolution ◽  
White Dwarf ◽  
Extreme Ultraviolet ◽  
Cataclysmic Variables ◽  
Ultraviolet Spectroscopy ◽  
Temperature Structure ◽  
Polar Cap ◽  
Ultraviolet Emission ◽  
X Ray ◽  
Magnetic Cataclysmic Variables

A longstanding problem in the interpretation of the X-ray and extreme ultraviolet emission from strongly magnetic cataclysmic variables can be addressed definitively with high resolution EUV spectroscopy. A detailed photospheric spectrum of the accretion-heated polar cap of the white dwarf is sensitive in principle to the temperature structure of the atmosphere. This may allow us to determine where and how the bulk of the accretion energy is thermalized. The EUVE data on AM Herculis and EF Eridani are presented and discussed in this context.

scholarly journals The Characteristics of Magnetic CVs in the Period Gap

2004 ◽  
Vol 190 ◽  
pp. 15-21 ◽  
Author(s):  
Gaghik Tovmassian ◽  
Sergey Zharikov ◽  
Ronald Mennickent ◽  
Jochen Greiner
Keyword(s):  
Mass Transfer ◽  
Orbital Period ◽  
Accretion Rate ◽  
Cataclysmic Variables ◽  
Magnetic Systems ◽  
Transfer Rates ◽  
Significant Difference ◽  
Magnetic Cataclysmic Variables

AbstractWe have observed several magnetic cataclysmic variables located in the range between 2 and 3 hours, known as the period gap. This work was prompted by the recent discovery of RXJ1554.2+2721. It has 2.54 hours orbital period and shows almost pure cyclotron continuum in a low luminosity state, similar to HS1023+3900, HS0922+1333 and RBS206. These are low accretion rate polars (LARPs) known to have mass transfer rates of order of a few 10-13M⊙/year. The aim of the study was to find out, if magnetic systems filling the period gap are in any way different from their counterparts outside that range of periods. The only significant difference we encounter is a much higher number of asynchronous magnetic systems towards longer periods than below the gap.

scholarly journals On the Classification of Magnetic Cataclysmic Variables

2004 ◽  
Vol 194 ◽  
pp. 180-181
Author(s):  
Paul A. Mason
Keyword(s):  
Classification Scheme ◽  
Cataclysmic Variables ◽  
Intermediate Polars ◽  
Orbital Periods ◽  
Magnetic Cataclysmic Variables

AbstractThe classification scheme for Magnetic Cataclysmic Variables (MCVs) is addressed. When only ten or twenty MCVs had been discovered their classification was simple and based on direct observational properties. Now that the number of MCVs exceeds one hundred, the method of classification needs updating. One important consideration is the possibility that binaries might physically change their classification. For example will intermediate polars become polars as they evolve to shorter orbital periods? Or does a polar become an intermediate polar when synchronism is broken due to a nova?

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.

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