scholarly journals Uncovering Flickering in Time-Resolved Spectroscopy for the Nova-like Variable UX Ursa Majoris

1997 ◽  
Vol 163 ◽  
pp. 834-834
Author(s):  
James C. White
Keyword(s):  
Cataclysmic Variables ◽  
Doppler Tomography ◽  
Time Resolved ◽  
Strong Emission ◽  
Secondary Star ◽  
Emission Component ◽  
Early Results ◽  
Usual Location ◽  
Spectroscopic Signatures ◽  
Tomographic Analysis

AbstractThe flickering phenomenon in cataclysmic variables (CVs) is manifest photometrically as variations in system brightness with amplitudes up to about 1 mag and on timescales from seconds to tens of minutes. Although a pronounced characteristic of CVs, flickering has been studied, in general, only tangentially and in the context of overall CV photometric properties. It is usually uncovered in CV photometry, yet my Doppler tomographic analysis of data collected on the KPNO 2.1-meter telescope in 1982 by Schlegel, Honeycutt, and Kaitchuck (1983) for the nova-like variable UX Ursa Majoris suggests that flickering also exists in this system’s spectroscopy.Using the integrated continuum flux from the UX UMa observations and Bruch’s (1992) methodology for classifying high- and low-flicker data, I constructed two data subsets corresponding to high- and low-flicker states. I generated Doppler tomograms of these high- and low-flicker states and interpret differences between the tomograms as spectroscopic signatures of flickering in the system.In UX UMa’s Hβ Doppler tomograms, a small, faint, incomplete ring of emission is visible for both flickering states. Dominating ring emission is strong emission in the (+Vx,+Vy) quadrant. The usual location for Swave emission, in the (−Vx,+Vy) quadrant, is here the region of faintest emission. Differenced Doppler tomograms, produced by subtracting from the tomograms the symmetric ring-emission component, show clear differences between the high- and low-flicker states. Further, these early results suggest Doppler tomography may be a useful technique for studying the secondary stars in CVs imaged in this manner. Enhanced chromospheric activity of the red dwarf companion is clearly visible in the high-flickering state tomogram at (0, Krd) and may, therefore, afford investigators the opportunity to estimate the chromospheric flux and radial velocity of the secondary star.

scholarly journals Simultaneous Stokes Imaging and Doppler tomography of MCVs

2004 ◽  
Vol 190 ◽  
pp. 78-84
Author(s):  
Stephen Potter ◽  
Encarni Romero-Colmenero ◽  
David Buckley ◽  
Derren Wood
Keyword(s):  
White Dwarf ◽  
Cataclysmic Variables ◽  
Doppler Tomography ◽  
Spectroscopic Observations ◽  
Secondary Star ◽  
Magnetically Confined ◽  
Magnetic Cataclysmic Variables

AbstractStokes imaging uses polarimetric observations in order to image indirectly the accretion region on the surface of the white dwarf in magnetic cataclysmic variables (MCVs). Doppler tomography uses spectroscopic observations in order to gain insights into the velocity dynamics of the secondary star, and the ballistic and magnetically confined parts of the accretion stream. Until now, both of these techniques have been applied separately. We present and compare the results of applying both techniques to simultaneous spectroscopic and polarimetric observations of MCVs.

scholarly journals Catching VY Sculptoris in a low state

2018 ◽  
Vol 617 ◽  
pp. A16 ◽  
Author(s):  
L. Schmidtobreick ◽  
E. Mason ◽  
S. B. Howell ◽  
K. S. Long ◽  
A. F. Pala ◽  
...  
Keyword(s):  
White Dwarf ◽  
Cataclysmic Variables ◽  
Emission Lines ◽  
High Mass ◽  
Absorption Bands ◽  
Radial Velocity Curve ◽  
Time Resolved ◽  
Time Resolved Spectroscopy ◽  
Secondary Star ◽  
Narrow Emission

Context. In the context of a large campaign to determine the system parameters of high mass transfer cataclysmic variables, we found VY Scl in a low state in 2008. Aims. Making use of this low state, we study the stellar components of the binary with little influence of the normally dominating accretion disc. Methods. Time-resolved spectroscopy and photometry of VY Scl taken during the low state are presented. We analysed the lightcurve and radial velocity curve and use time-resolved spectroscopy to calculate Doppler maps of the dominant emission lines. Results. The spectra show narrow emission lines of Hα, Hβ, He I, Na I D, and Fe II, as well as faint TiO absorption bands that trace the motion of the irradiated secondary star, and Hα and He I emission line wings that trace the motion of the white dwarf. From these radial velocities, we find an orbital period of 3.84 h, and put constraints on binary parameters such as the mass ratio M2/M1 of 0.43 and the inclination of 15°. With a secondary’s mass between 0.3 and 0.35 M⊙, we derive the mass for the white dwarf as M1 = 0.6–1.1 M⊙.

scholarly journals Voracious vortices in cataclysmic variables

2020 ◽  
Vol 642 ◽  
pp. A100
Author(s):  
V. V. Neustroev ◽  
S. V. Zharikov
Keyword(s):  
Cataclysmic Variables ◽  
Accretion Disc ◽  
Emission Lines ◽  
Quiescent State ◽  
Doppler Tomography ◽  
Time Resolved ◽  
Balmer Lines ◽  
Cool Gas ◽  
The Right ◽  
Three Body

Context. In Paper I we showed that the accretion disc radius of the dwarf nova HT Cas in its quiescent state has not changed significantly during many years of observations. It has remained consistently large, close to the tidal truncation radius. This result is inconsistent with the modern understanding of the evolution of the disc radius through an outburst cycle. Aims. Spectroscopic observations of HT Cas during its superoutburst offered us an exceptional opportunity to compare the properties of the disc of this object in superoutburst and in quiescence. Methods. We obtained a new set of time-resolved spectra of HT Cas in the middle of its 2017 superoutburst. We used Doppler tomography to map emission structures in the system, which we compared with those detected during the quiescent state. We used solutions of the restricted three-body problem to discuss again the location of emission structures and the disc size of HT Cas in quiescence. Results. The superoutburst spectrum is similar in appearance to the quiescent spectra, although the strength of most of the emission lines decreased. However, the high-excitation lines significantly strengthened in comparison with the Balmer lines. Many lines show a mix of broad emission and narrow absorption components. Hα in superoutburst was much narrower than in quiescence. Other emission lines have also narrowed in outburst, but they did not become as narrow as Hα. Doppler maps of Hα in quiescence and of the Hβ and He I lines in outburst are dominated by a bright emission arc at the right side of the tomograms, which is located at and even beyond the theoretical truncation limit. However, the bulk of the Hα emission in outburst has significantly lower velocities. Conclusions. We show that the accretion disc radius of HT Cas during its superoutburst has become hot but remained the same size as it was in quiescence. Instead, we detected cool gas beyond the Roche lobe of the white dwarf that may have been expelled from the hot disc during the superoutburst.

Phase-resolved Spectroscopy and Photometry of the Eclipsing Polar UZ Fornacis

2017 ◽  
Vol 14 (S339) ◽  
pp. 314-317
Author(s):  
Z. N. Khangale ◽  
S. B. Potter ◽  
P. A. Woudt
Keyword(s):  
Doppler Tomography ◽  
Strong Emission ◽  
Secondary Star ◽  
Magnetically Confined ◽  
Balmer Lines

AbstractThe blue continuum of the eclipsing polar UZ For is dominated by single- or double-peaked emission from He ii, He i and the Balmer lines. The red spectrum shows weak emission from the Na i doublet at λ 8183 and 8194 Å and strong emission from the Ca ii lines at λ 8498 and 8542 Å. Doppler tomography of the strongest emission features reveals the presence of emission from the irradiated face of the secondary star, the threading region, and the ballistic and magnetically confined accretion stream. We have obtained 28 new eclipse times of UZ For during 2011–2016 as part of our eclipse timing follow-up programme to test the two-planet model proposed to explain variations in the eclipse times of UZ For.

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.

Atlas of time-resolved spectrophotometry of cataclysmic variables

1987 ◽  
Vol 65 ◽  
pp. 451 ◽  
Author(s):  
R. Kent Honeycutt ◽  
Eric M. Schlegel ◽  
Ronald H. Kaitchuck
Keyword(s):  
Cataclysmic Variables ◽  
Time Resolved

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.

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