scholarly journals Mapping the Line Emission Distribution of Cataclismic Variable Stars

1987 ◽  
Vol 93 ◽  
pp. 85-89
Author(s):  
T.R. Marsh ◽  
K. Horne
Keyword(s):  
Formation Process ◽  
Variable Star ◽  
Line Emission ◽  
Variable Stars ◽  
Accretion Disc ◽  
Bright Spot ◽  
Cataclysmic Variable ◽  
Two Dimensional ◽  
Line Formation ◽  
Line Profiles

AbstractWe describe a method for imaging the accretion disc of a Cataclysmic Variable star. We use the two-dimensional information contained in the line profiles as they vary with phase to invert the line formation process. Asymmetries in the disc, as are caused by the bright-spot, for example, are accounted for naturally.

scholarly journals Time Dependence of the UV Resonance Lines in the Cataclysmic Variable Star VW Hyi

1995 ◽  
Vol 151 ◽  
pp. 280-281
Author(s):  
M.T. Özkan ◽  
T. Ak ◽  
A.T. Saygac ◽  
H.H. Esenoglu ◽  
S. Guler
Keyword(s):  
Time Dependence ◽  
Variable Star ◽  
Cataclysmic Variable ◽  
Data Archive ◽  
Line Profiles ◽  
Dwarf Nova ◽  
International Ultraviolet Explorer

AbstractIn this work, we study orbital variations in the ultraviolet resonance lines of the SU UMa type dwarf nova VW Hyi examining spectra in the data archive of the International Ultraviolet Explorer (IUE). We show that VW Hyi exhibits an orbital and long term variability in terms of UV line profiles and continuum flux at 1450 Å during superoutburst.

scholarly journals A spectroscopic analysis of the eclipsing nova-like EC 21178−5417 – discovery of spiral density structures

2020 ◽  
Vol 495 (1) ◽  
pp. 637-649 ◽  
Author(s):  
Z N Khangale ◽  
P A Woudt ◽  
S B Potter ◽  
B Warner ◽  
D Kilkenny ◽  
...  
Keyword(s):  
Mass Transfer Rate ◽  
Spectral Characteristics ◽  
Line Emission ◽  
Pure Line ◽  
Accretion Disc ◽  
Bright Spot ◽  
Balmer Series ◽  
Secondary Star ◽  
Average Spectrum ◽  
Balmer Lines

ABSTRACT We present phase-resolved optical spectroscopy of the eclipsing nova-like cataclysmic variable EC 21178−5417 obtained between 2002 and 2013. The average spectrum of EC 21178−5417 shows broad double-peaked emission lines from He ii 4686 Å (strongest feature) and the Balmer series. The high-excitation feature, C iii/N iii at 4640–4650 Å, is also present and appears broad in emission. A number of other lines, mostly He i, are clearly present in absorption and/or emission. The average spectrum of EC 21178−5417 taken at different months and years shows variability in spectral features, especially in the Balmer lines beyond Hγ, from pure line emission, mixed line absorption, and emission to pure absorption lines. Doppler maps of the He ii 4686 Å emission reveal the presence of a highly inclined asymmetric accretion disc and a two spiral arm-like structure, whereas that of the Balmer lines (Hα and Hβ) reveal a more circular accretion disc. There is no evidence of a bright-spot in the Doppler maps of EC 21178−5417 and no emission from the secondary star is seen in the tomograms of the He ii 4686 Å and Balmer lines. Generally, the emission in EC 21178−5417 is dominated by emission from the accretion disc. We conclude that EC 21178−5417 is a member of the RW Tri or UX UMa subtype of nova-like variables based on these results and because it shows different spectral characteristics at different dates. This spectral behaviour suggests that EC 21178−5417 undergoes distinct variations in mass transfer rate on the observed time-scales of months and years.

scholarly journals Cataclysmic Variable Stars

1984 ◽  
Vol 80 ◽  
pp. 127-137
Author(s):  
G. T. Bath
Keyword(s):  
Mass Transfer ◽  
White Dwarf ◽  
Variable Stars ◽  
Accretion Disc ◽  
Cataclysmic Variable ◽  
Subsequent Evolution ◽  
Dynamical Instabilities

AbstractThe properties of cataclysmic variable outbursts are reviewed, and interpreted in terms of dynamical instabilities by the red component, and subsequent evolution of the white dwarf accretion disc subject to a mass transfer burst in the transfer stream.

scholarly journals How Does One Detect An Accretion Disk?

1992 ◽  
Vol 151 ◽  
pp. 175-183
Author(s):  
Ronald H. Kaitchuck
Keyword(s):  
Binary System ◽  
Emission Line ◽  
Accretion Disk ◽  
Variable Stars ◽  
Emission Lines ◽  
New Technique ◽  
Cataclysmic Variable ◽  
Line Profiles ◽  
Doppler Tomography ◽  
History Of

The history of the first detection of an accretion disk in a interacting binary system is presented. The nature of transient and permanent disks in Algol-type binaries is discussed as are the problems associated with the interpretation of emission line profiles from the disks in cataclysmic variable stars. The new technique of eclipse mapping from continuum photometry is reviewed. Some results of Doppler tomography of emission lines are presented.

scholarly journals Disc–magnetosphere interactions in cataclysmic variable stars

2007 ◽  
Vol 3 (S243) ◽  
pp. 325-336 ◽  
Author(s):  
Coel Hellier
Keyword(s):  
Magnetic Fields ◽  
White Dwarf ◽  
Variable Stars ◽  
Accretion Disc ◽  
Accretion Discs ◽  
Cataclysmic Variable ◽  
Accretion Flows ◽  
Slow Moving ◽  
Field Lines ◽  
Nova Outbursts

AbstractI review, from an observational perspective, the interactions of accretion discs with magnetic fields in cataclysmic variable stars. I start with systems where the accretion flows via a stream, and discuss the circumstances in which the stream forms into an accretion disc, pointing to stars which are close to this transition. I then turn to disc-fed systems and discuss what we know about how material threads on to field lines, as deduced from the pattern of accretion footprints on the white dwarf. I discuss whether distortions of the field lines are related to accretion torques and the changing spin periods of the white dwarfs. I also review the effect on the disc–magnetosphere interaction of disc-instability outbursts. Lastly, I discuss the temporary, dynamo-driven magnetospheres thought to occur in dwarf-nova outbursts, and whether slow-moving waves are excited at the inner edges of the disc.

scholarly journals KIC 9406652: A laboratory for tilted disks in cataclysmic variable stars

2020 ◽  
Vol 72 (6) ◽  
Author(s):  
Mariko Kimura ◽  
Yoji Osaki ◽  
Taichi Kato
Keyword(s):  
Cataclysmic Variables ◽  
Orbital Plane ◽  
Variable Stars ◽  
Bright Spot ◽  
Cataclysmic Variable ◽  
Secondary Star ◽  
Orbital Phase ◽  
Rich Information ◽  
Long Timescales ◽  
Tilted Disk

Abstract KIC 9406652 is a cataclysmic variable, sub-classified as an “IW And-type” star, which shows repeated standstills with oscillatory variations terminated by brightening. This system shows negative superhumps, semi-periodic variations having periods slightly shorter than the ∼6 hr orbital period, and super-orbital signals having ∼4 d periods, both of which are believed to originate from a precessing, tilted accretion disk. We have re-examined its Kepler light curve over 1500 d. In accordance with a cycle of IW And-type light variation, the frequency of negative superhumps showed reproducible variation: a rapid drop during the brightening and a gradual increase during the standstill. This is interpreted as a drastic change in the radial mass distribution and the expansion of the tilted disk, which is not expected from the existing models of IW And stars. The constancy in flux amplitudes of the negative superhumps confirms that their light source is the bright spot sweeping across the surface of the tilted disk. The frequencies of the negative superhumps and super-orbital signals varied in unison on long timescales, suggesting their common origin: the tilted disk. The orbital signals at the brightening were dominated by the irradiation of the secondary star and varied with the orientation of the tilted disk; the amplitude was maximized at the minimum of the super-orbital signals, and the light maximum shifted to early orbital phases as the super-orbital phase advanced. This is the first direct evidence that the disk is tilted out of the binary orbital plane and is retrogradely precessing. The tilt angle of the disk inferred from semi-amplitudes of super-orbital signals was lower than 3°. The diversity in light curves of the negative superhumps supports this and suggests that part of the gas stream overflows the disk edge. This study thus offers rich information about the tilted disk in cataclysmic variables.

scholarly journals Observations of Dwarf Novae

1976 ◽  
Vol 73 ◽  
pp. 85-140 ◽  
Author(s):  
B. Warner
Keyword(s):  
Hot Spot ◽  
Variable Stars ◽  
Accretion Disc ◽  
Cataclysmic Variable ◽  
Dwarf Novae ◽  
X Ray ◽  
Classical Novae ◽  
Photometric Observations ◽  
Spot Model ◽  
Hot Spot Model

Spectroscopic and photometric observations relevant to the structure of classical novae, recurrent novae and dwarf novae are collected together. Details are given of optical, infrared, satellite ultraviolet, X-ray and radio observations. Most of these can be understood in terms of the hot spot model of cataclysmic variable stars. Estimates are made of luminosities, temperatures and rates of mass transfer. Observations made during eruptions of dwarf novae imply large changes taking place in the accretion disc.

FIRST RESULTS FROM TIEN-SHAN SURVEY TO SEARCH FOR VARIABLE STARS: LIGHTCURVE ANALYSIS AND VARIABLE STAR CLASSIFICATION

2020 ◽  
Vol 3 (331) ◽  
pp. 81-91
Author(s):  
Serebryanskiy A., ◽  
◽  
Aimanova G. K., ◽  
Kondratyeva L.N., ◽  
Omarov Ch., ◽  
...  
Keyword(s):  
Variable Star ◽  
Variable Stars ◽  
Tien Shan ◽  
First Results ◽  
Star Classification
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