WZ Sagittae as a DQ Herculis star
نویسندگان
چکیده
We argue that quiescent WZ Sge is a rapidly spinning magnetic rotator in which most of the matter transfered from the secondary is ejected from the system. Assuming that the observed 27.87 s oscillation period is due to the spinning white dwarf we propose that the other observed principal period of 28.96 s is a beat due to reprocessing of the rotating white dwarf beam on plasma blobs in Keplerian rotation at the outer disc rim. The weaker, transient, 29.69 s period is identified as a beat with the Keplerian period of the magnetosphere. WZ Sge evolves through a cycle of spin-up and spindown phases. During the spin-down phase it is a DQ Her star, during the spin-up phase it should be a ER UMa star.
منابع مشابه
WZ Sagittae - an old dwarf nova
We model the evolution of the accretion disk of WZ Sagittae during the long quiescence. We find that the large amount of mass in the disk derived from the outburst luminosity is a severe constraint and demands values of αc ≈ 0.001 in contradiction to some recent suggestions. We include in our computations the formation of an inner disk hole and the growth of the disk due to redistribution of an...
متن کاملKeck Infrared Spectroscopy of Wz Sagittae: Detection of Molecular Emission from the Accretion Disk
Time-resolved IR spectroscopy of WZ Sge was obtained using NIRSPEC on Keck II. We detect CO and H2 emission from the accretion disk, placing WZ Sge in a rarefied class of astronomical objects including young stellar objects and high-luminosity early-type stars. During the eclipse phase, the molecular emission greatly weakens, but no firm evidence for the secondary star is seen, allowing new lim...
متن کاملMass transfer in tidally unstable compact binaries
The 2001 outburst of WZ Sagittae has shown the most compelling evidence yet for an enhancement of the mass transfer rate from the donor star during a dwarf nova outburst in the form of hot-spot brightening. I show that even in this extreme case, the brightening can be attributed to tidal heating near the interaction point of an accretion stream with the expanding edge of an eccentric accretion ...
متن کاملThe 2001 Superoutburst of WZ Sagittae: A Clue to the Dynamics of Accretion Disks
We examine the light curve of the July-August 2001 superoutburst of WZ Sagittae. During the decline from maximum light the locally defined decay time increases from ∼ 4 d mag to ∼ 12 d mag over the first ∼ 15 d of the ∼ 25 d superoutburst, as the system faded from mV ≃ 8.5 to mV ≃ 10. The superoutburst is caused by the sudden accretion of ∼ 10 g of gas onto the white dwarf, and the deviation fr...
متن کاملHelical Tomography of an Accretion Disk by Superhump Light Curves of the 2001 Outburst of WZ Sagittae
A new method for analyzing complex superhump light curves for the 2001 outburst of WZ Sagittae is proposed. The complexity arises because intrinsically time-varying and non-axisymmetric distributions of superhump light sources are coupled with the aspect effects around the binary orbital phase because of its high orbital inclination. The new method can disentangle these complexities by separati...
متن کامل