scholarly journals Structure of accretion flows in the nova-like cataclysmic variable RW Tri

2020 ◽  
Vol 497 (2) ◽  
pp. 1475-1487
Author(s):  
G Subebekova ◽  
S Zharikov ◽  
G Tovmassian ◽  
V Neustroev ◽  
M Wolf ◽  
...  
Keyword(s):  
Binary Systems ◽  
Cataclysmic Variable ◽  
Low Velocity ◽  
Time Resolved ◽  
Narrow Component ◽  
Accretion Flows ◽  
Photometric Observations ◽  
Hα Emission ◽  
Usual Interpretation ◽  
Velocity Region

ABSTRACT We obtained photometric observations of the nova-like (NL) cataclysmic variable RW Tri and gathered all available AAVSO and other data from the literature. We determined the system parameters and found their uncertainties using the code developed by us to model the light curves of binary systems. New time-resolved optical spectroscopic observations of RW Tri were also obtained to study the properties of emission features produced by the system. The usual interpretation of the single-peaked emission lines in NL systems is related to the bi-conical wind from the accretion disc’s inner part. However, we found that the Hα emission profile is comprised of two components with different widths. We argue that the narrow component originates from the irradiated surface of the secondary, while the broader component’s source is an extended, low-velocity region in the outskirts of the accretion disc, located opposite to the collision point of the accretion stream and the disc. It appears to be a common feature for long-period NL systems – a point we discuss.

scholarly journals Hα Spectroscopy of WW Cet

1997 ◽  
Vol 163 ◽  
pp. 814-815
Author(s):  
C. Tappert ◽  
W. Wargau ◽  
R.W. Hanuschik
Keyword(s):  
World Wide Web ◽  
Emission Line ◽  
Spectroscopic Data ◽  
World Wide ◽  
Radial Velocities ◽  
Cataclysmic Variable ◽  
Time Resolved ◽  
The World ◽  
Hα Emission ◽  
Different Parts

AbstractTime-resolved spectroscopic data of the cataclysmic variable WW Cet were taken during quiescence, outburst, and decline from outburst. The profile of the Hα emission line is studied by measuring radial velocities of different parts of the line.The complete poster is available on the World Wide Web at http://www. astro, ruhr-uni-bochum.de/cta/paper.html.

scholarly journals Double-Peaked Flare Events on red Dwarf Stars and Solar ‘Sympathetic’ Flares

1976 ◽  
Vol 71 ◽  
pp. 475-475
Author(s):  
M. Rodonò
Keyword(s):  
Proximity Effect ◽  
Binary Systems ◽  
Angular Separation ◽  
Dwarf Stars ◽  
Multiple Systems ◽  
Photometric Observations ◽  
Red Dwarfs ◽  
Flare Stars ◽  
Red Dwarf Stars ◽  
The Individual

About 50% of the flare events observed on red dwarfs are at least double-peaked. As the majority of flare stars are members of double or multiple systems, the possibility that time-overlapping flares originate quasi-simultaneously on the individual components is discussed.Assuming a poissonian occurrence of flares in both components, the expected probability of observing double-peaked flares is lower than 1% for the most active binary systems.However, from photometric observations of the double flare star EQ Peg (BD +19°5116 AB) carried out by the author with an area scanner (the components' angular separation is 3.7″) about 20% of the observed flares have been found to be double-peaked flares resulting from separate flares, one in each component. A direct flare triggering of the following flare by the preceding one can be ruled out since the light travel-time between the two components is 3.5 h, while the observed time delay between the flare peaks is about 10 min. Moreover, the proximity effect does not seem to play an important triggering role.It is concluded that, although the analogy with solar ‘sympathetic’ flares is not always applicable, it is the most promising framework within which the majority of double-peaked flare events on red dwarfs must be interpreted.

High-energy X-ray diffuse scattering

2009 ◽  
Vol 42 (3) ◽  
pp. 392-400 ◽  
Author(s):  
I. B. Ramsteiner ◽  
A. Schöps ◽  
H. Reichert ◽  
H. Dosch ◽  
V. Honkimäki ◽  
...  
Keyword(s):  
Multiple Scattering ◽  
Diffuse Scattering ◽  
Binary Systems ◽  
High Energy ◽  
Absorption Length ◽  
Time Resolved ◽  
X Ray ◽  
Order Of Magnitude ◽  
Extinction Length ◽  
Scattering Volume

Diffuse X-ray scattering has been an important tool for understanding the atomic structure of binary systems for more than 50 years. The majority of studies have used laboratory-based sources providing 8 keV photons or synchrotron radiation with similar energies. Diffuse scattering is weak, with the scattering volume determined by the X-ray absorption length. In the case of 8 keV photons, this is not significantly different from the typical extinction length for Bragg scattering. If, however, one goes to energies of the order of 100 keV the scattering volume for the diffuse scattering increases up to three orders of magnitude while the extinction length increases by only one order of magnitude. This leads to a gain of two orders of magnitude in the relative intensity of the diffuse scattering compared with the Bragg peaks. This gain, combined with the possibility of recording the intensity from an entire plane in reciprocal space using a two-dimensional X-ray detector, permits time-resolved diffuse scattering studies in many systems. On the other hand, diffraction features that are usually neglected, such as multiple scattering, come into play. Four types of multiple scattering phenomena are discussed, and the manner in which they appear in high-energy diffraction experiments is considered.

Further Photometric Observations of the Cataclysmic Variable PG 1012-029

1993 ◽  
pp. 537-541
Author(s):  
B. N. Ashoka ◽  
T. M. K. Marar ◽  
S. Seetha ◽  
K. Kasturirangan ◽  
U. R. Rao ◽  
...  
Keyword(s):  
Cataclysmic Variable ◽  
Photometric Observations

The Evolution of Cataclysmic Variable Binary Systems with Circumbinary Disks

2001 ◽  
Vol 561 (1) ◽  
pp. 329-336 ◽  
Author(s):  
Ronald E. Taam ◽  
H. C. Spruit
Keyword(s):  
Binary Systems ◽  
Cataclysmic Variable

scholarly journals Spectroscopic and Photometric Observations of the Magnetic Cataclysmic Variable TX Col

2004 ◽  
Vol 190 ◽  
pp. 156-162
Author(s):  
Nceba Mhlahlo ◽  
Stephen B. Potter ◽  
David Buckley
Keyword(s):  
Orbital Period ◽  
Power Spectra ◽  
Radial Velocities ◽  
Cataclysmic Variable ◽  
Beat Period ◽  
Spin Period ◽  
Photometric Observations ◽  
Optical Wavelengths ◽  
First Time

AbstractSimultaneous photometry and spectroscopy of the Intermediate Polar TX Col were obtained in order to investigate its accretion mode and dynamics. The spectroscopic and photometric power spectra of TX Col are observed to change on relatively short timescales. Spectroscopy reveals a dominant periodicity at the orbital period (5.69 hr) and a spin period of 1909 s in radial velocities, while line equivalent widths show a strong periodicity at the beat period (2106 s). It is the first time that the orbital period has been detected in optical wavelengths.

A simultaneous inversion of seismic traveltimes and amplitudes for velocity and attenuation

Geophysics ◽  
1996 ◽  
Vol 61 (6) ◽  
pp. 1738-1757 ◽  
Author(s):  
Don W. Vasco ◽  
John E. Peterson ◽  
Ernest L. Majer
Keyword(s):  
Perturbation Approach ◽  
Well Log ◽  
Ray Theory ◽  
Fracture Zones ◽  
Low Velocity ◽  
Simultaneous Inversion ◽  
Attenuation Structure ◽  
Paraxial Ray ◽  
The Relationship ◽  
Velocity Region

It is possible to efficiently use traveltime and amplitude information to infer variations in velocity and Q. With little additional computation, terms accounting for source radiation pattern and receiver coupling may be included in the inversion. The methodology is based upon a perturbation approach to paraxial ray theory. The perturbation approach linearizes the relationship between velocity deviations and traveltime and amplitude anomalies. Using the technique, we infer the velocity and attenuation structure at a fractured granitic site near Raymond, California. A set of four well pairs are examined and each is found to contain two zones of strong attenuation. The velocity variations contain an upper low velocity region corresponding to the uppermost attenuating zone. The location of these zones agrees with independent well‐log and geophysical data. The velocity and attenuation anomalies appear to coincide with extensively fractured sections of the borehole and may indicate fracture zones rather than individual fractures.

scholarly journals A three-dimensional study of a crustal low velocity region beneath the 9°03′N overlapping spreading center

2003 ◽  
Vol 30 (2) ◽  
Author(s):  
S. Bazin ◽  
A. J. Harding ◽  
G. M. Kent ◽  
J. A. Orcutt ◽  
S. C. Singh ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Spreading Center ◽  
Low Velocity ◽  
Velocity Region

scholarly journals On the nature of ultra-luminous X-ray sources from optical/IR measurements

2006 ◽  
Vol 2 (S238) ◽  
pp. 251-254
Author(s):  
Mark Cropper ◽  
Chris Copperwheat ◽  
Roberto Soria ◽  
Kinwah Wu
Keyword(s):  
Binary Systems ◽  
Mass Transfer Rate ◽  
Photometric Data ◽  
Type B ◽  
Irradiation Effects ◽  
Time Resolved ◽  
X Ray ◽  
Infra Red ◽  
Additional Constraints ◽  
Acceptable Parameter

AbstractWe present a model for the prediction of the optical/infra-red emission from ULXs. In the model, ULXs are binary systems with accretion taking place through Roche lobe overflow. We show that irradiation effects and presence of an accretion disk significantly modify the optical/infrared flux compared to single stars, and also that the system orientation is important. We include additional constraints from the mass transfer rate to constrain the parameters of the donor star, and to a lesser extent the mass of the BH. We apply the model to fit photometric data for several ULX counterparts. We find that most donor stars are of spectral type B and are older and less massive than reported elsewhere, but that no late-type donors are admissible. The degeneracy of the acceptable parameter space will be significantly reduced with observations over a wider spectral range, and if time-resolved data become available.

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