scholarly journals Spectroscopy of the Primary and Secondary Components of the Dwarf Nova AH Herculis

1987 ◽  
Vol 93 ◽  
pp. 123-124
Author(s):  
A. Bruch
Keyword(s):  
Cataclysmic Variables ◽  
Dwarf Nova ◽  
Secondary Star ◽  
V Band ◽  
Visual Magnitude ◽  
Total Light ◽  
Composite Nature ◽  
Astronomy And Astrophysics ◽  
Calar Alto ◽  
Complete Account

AbstractThe dwarf nova AH Her belongs to those cataclysmic variables which show a composite spectrum in the optical range, containing emission lines from the accretion disk and absorptions from the secondary star. This has been shown by Horne et al. (1986). Anticipating the composite nature of the spectrum from the the B-V colour of AH Her, which is intrinsically redder then , I took spectra of the system in four nights in June 1984 at the 1.2-m-telescope of the DSAZ on Calar Alto in order to detect the secondary component. The wavelength range observed was 5300 Å – 7150 Å. Apart from H in emission which behaves in the same way as described by Horne et al., the spectra show in fact a definite absorption of the Na D lines to be attributed to the secondary star. The linestrength and the absence of any strong TiO features confines the spectral type of the secondary to between K2 and MO. It is possible to calculate the relative contributions of the primary and secondary to the total light at the wavelength of Na D as a function of the exact spectral subtype of the secondary, using the measured equivalent width of the Na D lines. Taking the spectral gradient of primary and secondary from the current literature the same can be done for the effective wavelength of the V band. It is then straightforward to calculate the system’s absolute visual magnitude and the distance. It turns out that AH Her is one of the intrinsically brightest dwarf novae known, regardless of the exact spectral subtype of the secondary.A complete account of the observations of AH Her and of the interpretations is given in a paper which has been submitted to Astronomy and Astrophysics.

scholarly journals The Orbital Period of Nova V2540 Ophiuchi (2002)

2005 ◽  
Vol 22 (4) ◽  
pp. 298-305 ◽  
Author(s):  
Tansel Ak ◽  
Alon Retter ◽  
Alex Liu
Keyword(s):  
Orbital Period ◽  
Spiral Structure ◽  
Cataclysmic Variables ◽  
Distance Modulus ◽  
Maximum Magnitude ◽  
Reflection Effect ◽  
Ccd Photometry ◽  
Secondary Star ◽  
Visual Magnitude ◽  
Rate Of Decline

AbstractWe present the results of 26 nights of CCD photometry of the nova V2540 Oph (2002) from 2003 to 2004. We find a period of 0.284781 ± 0.000006 d (6.8347 ± 0.0001 h) in the data. Since this period was present in the light curves taken in both years, with no apparent change in its value or amplitude, we interpret it as the orbital period of the nova binary system. The mass–period relation for cataclysmic variables yields a secondary mass of about 0.75 ± 0.04 M⊙. From maximum magnitude–rate of decline relation, we estimate a maximum absolute visual magnitude of MV = −6.2 ± 0.4 mag. This value leads to an uncorrected distance modulus of (m – M) = 14.7 ± 0.7. By using the interstellar reddening for the location of V2540 Oph, we find a rough estimate for the distance of 5.2 ± 0.8 kpc. We propose that V2540 Oph is either (1) a high-inclination cataclysmic variable showing a reflection effect of the secondary star, or having a spiral structure in the accretion disc, (2) a high-inclination intermediate polar system, or less likely (3) a polar.

Models of Cataclysmic Variables from Photometric and Spectroscopic Data

1979 ◽  
Vol 46 ◽  
pp. 65-74 ◽  
Author(s):  
A.C. Fabian ◽  
J.E. Pringle ◽  
J.A.J. Whelan ◽  
J.A. Bailey
Keyword(s):  
Spectroscopic Data ◽  
Cataclysmic Variables ◽  
System Parameters ◽  
Dwarf Nova ◽  
Spectroscopic Observations ◽  
Photometric And Spectroscopic Observations

Abstract.Recent photometric and spectroscopic observations of the dwarf nova system Z Cha are discussed. Methods for constraining the system parameters are applied and the disc emissivity is deduced as a function of radius. Indications are found that the disc shrinks in size with increasing time after outburst.

scholarly journals Long-Term Variability and Outburst Activity of FS Aurigae: Further Evidence for a Third Body in the System

2011 ◽  
Vol 7 (S282) ◽  
pp. 79-80
Author(s):  
V. Neustroev ◽  
G. Sjoberg ◽  
G. Tovmassian ◽  
S. Zharikov ◽  
T. Arranz Heras ◽  
...  
Keyword(s):  
Transfer Rate ◽  
Mass Transfer Rate ◽  
Cataclysmic Variables ◽  
Close Binary ◽  
Third Body ◽  
Secondary Star ◽  
Long Term Monitoring ◽  
Binary Orbit ◽  
Term Monitoring

AbstractFS Aurigae is famous for a variety of uncommon and puzzling periodic photometric and spectroscopic variabilities which do not fit well into any of the established sub-classes of cataclysmic variables. Here we present preliminary results of long-term monitoring of the system, conducted during the 2010-2011 observational season. We show that the long-term variability of FS Aur and the character of its outburst activity may be caused by variations in the mass transfer rate from the secondary star as the result of eccentricity modulation of a close binary orbit induced by the presence of a third body on a circumbinary orbit.

scholarly journals 1RXS J232953.9+062814: A Dwarf Nova with a 64 Minute Orbital Period and a Conspicuous Secondary Star

2002 ◽  
Vol 567 (1) ◽  
pp. L49-L52 ◽  
Author(s):  
John R. Thorstensen ◽  
William H. Fenton ◽  
Joseph O. Patterson ◽  
Jonathan Kemp ◽  
Thomas Krajci ◽  
...  
Keyword(s):  
Orbital Period ◽  
Dwarf Nova ◽  
Secondary Star

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 Masses and Magnetic Fields of White Dwarfs in Cataclysmic Variables

1989 ◽  
Vol 114 ◽  
pp. 337-340
Author(s):  
J.P. Lasota ◽  
J.M. Hameury ◽  
A.R. King
Keyword(s):  
Magnetic Field ◽  
Angular Momentum ◽  
Magnetic Fields ◽  
White Dwarf ◽  
White Dwarfs ◽  
Cataclysmic Variables ◽  
Strong Support ◽  
Drastic Reduction ◽  
Secondary Star ◽  
Maximum Magnetic Field

We show that the existence of the AM Her period spike implies (i) a unique white dwarf mass ≃ 0.6 − 0.7M⊙ for most magnetic CV’s (ii) nova explosions remove exactly the accreted mass from magnetic white dwarfs, and (iii) the maximum magnetic field for most CV’s is ≤ 4 × 107 G. The existence of the spike is very strong support for the idea that the period gap results from a drastic reduction of angular momentum losses when the secondary star becomes fully convective.

scholarly journals Optical spectra of FO Aquarii during low and high accretion rates

2020 ◽  
Vol 495 (4) ◽  
pp. 4445-4462
Author(s):  
M R Kennedy ◽  
P M Garnavich ◽  
C Littlefield ◽  
T R Marsh ◽  
P Callanan ◽  
...  
Keyword(s):  
Transfer Rate ◽  
Mass Transfer Rate ◽  
Cataclysmic Variables ◽  
Accretion Disc ◽  
High State ◽  
Secondary Star ◽  
Accretion Rates ◽  
Magnetic Poles ◽  
The Impact ◽  
Impact Region

ABSTRACT Between 2016 May and 2018 September, the intermediate polar (IP) FO Aquarii exhibited two distinct low states and one failed low state. We present optical spectroscopy of FO Aquarii throughout this period, making this the first detailed study of an accretion disc during a low state in any IP. Analysis of these data confirm that the low states are the result of a drop in the mass transfer rate between the secondary star and the magnetic white dwarf primary, and are characterized by a decrease in the system’s brightness coupled with a change of the system’s accretion structures from an accretion disc-fed geometry to a combination of disc-fed and ballistic stream-fed accretion, and that effects from accretion on to both magnetic poles become detectable. The failed low state only displays a decrease in brightness, with the accretion geometry remaining primarily disc-fed. We also find that the WD appears to be exclusively accretion disc-fed during the high state. There is evidence for an outflow close to the impact region between the ballistic stream and the disc which is detectable in all of the states. Finally, there is marginal evidence for narrow high-velocity features in the H α emission line during the low states which may arise due to an outflow from the WD. These features may be evidence of a collimated jet, a long predicted yet elusive feature of cataclysmic variables.

scholarly journals Quasi-Periodic and Periodic Oscillations in the Dwarf Nova AH Her

1979 ◽  
Vol 53 ◽  
pp. 403-403
Author(s):  
J.G. Duthie ◽  
R.S. McMillan
Keyword(s):  
Light Curve ◽  
Autocorrelation Function ◽  
High Speed ◽  
Statistical Significance ◽  
Cataclysmic Variables ◽  
Power Spectra ◽  
Photometric System ◽  
Periodic Oscillations ◽  
Dwarf Nova ◽  
High Statistical Significance

With a high speed photometric system we have made extensive observation of the dwarf nova AH Her. We have detected rapid oscillations on two consecutive nights during the recovery portion of the light curve of a typical outburst during the spring of 1979. The periods and the sense of the change of period are consistent with previous observations of rapid oscillations of AH Her. On another occasion we detected quasi-periodic oscillations during the rising portion of an outburst. These are similar in appearance to quasi-periodic oscillations found in other cataclysmic variables in that they appear with high statistical significance in the autocorrelation function but are not apparent in power spectra (Robinson and Nather 1979). However they are different from those reported by Robinson and Nather in the sense that they have the same order of period as the periodic rapid oscillations typical of AH Her. These results will be presented together with a discussion of their Implications.

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