Time‐resolved Spectroscopy of V Sagittae

Unusual State in V Sagittae

It has been recently demonstrated that the recurring high/low states in the peculiar binary V Sge can be explained by considering the limit-cycle oscillation involving negative feedback by the wind on the mass-transfer from the secondary star. We noticed, from the recent observations reported to the VSNET, the presence of a different state of recurring variations (recurrence time ∼ 30 d) showin...

Keck 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...

The photometric and spectroscopic characterization of the V Sagittae star V617 Sagittarii

Photometric and spectroscopic characterization of the V Sge star V617 Sgr (WR 109) is presented. The orbital period, 0.207 day, is the shortest of its class. The optical light curve presents a double wave with minima and maxima of uneven brightness. Strong emission lines of highly ionized species such as HeII, NV and OVI dominate the optical spectrum. High and low photometric states have been o...

Timeresolved photoluminescence studies of InGaN epilayers

WZ Sagittae as a DQ Herculis star

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 Kepleri...