相关论文: Spiral Structure in WZ Sagittae around the 2001 Ou…

We report the results of a worldwide campaign to observe WZ Sagittae during its 2001 superoutburst. After a 23-year slumber at V=15.5, the star rose within 2 days to a peak brightness of 8.2, and showed a main eruption lasting 25 days. The…

We carried out optical spectroscopic observations of the most enigmatic dwarf nova WZ Sge in 11 nights during the 2001 superoutburst. Our observations covered the period from the initial phase, several hours before the maximum, to the ninth…

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…

We present spectroscopy of the dwarf nova IP Pegasi taken during two consecutive nights, 5 and 6 days after the start of an outburst. Even this late in the outburst, Doppler maps show marked spiral structure in the accretion disc, at least…

The short-period cataclysmic variable WZ Sge underwent its first dwarf nova outburst in 23 years in 2001 July. Here we describe 905-1187 Ang. spectra obtained with the Far Ultraviolet Spectroscopic Explorer (FUSE) during the outburst and…

A new mechanism explaining superoutbursts in binaries of SU UMa type is proposed. In the framework of this mechanism the accretion rate increase leading to the superoutburst is associated with formation of a spiral wave of a new…

We present seven nights' blue spectroscopy of the novalike variable star, V3885 Sgr. The line spectrum shows a typical combination of broad absorption and emission in H gamma and H beta and He I, which is associated with the accretion disk.…

We present an analysis of time-resolved, medium resolution optical spectroscopic observations of UX UMa in the blue (3920-5250 A) and red (6100-7200 A) wavelength ranges, that were obtained in April 1999 and March 2008 respectively. The…

Time resolved spectroscopic observations of U Gem during its March 2000 outburst show strong spiral shocks in the accretion disk. During the plateau at maximum brightness the spiral shocks contribute 14% to the total He II flux. The two…

We report on time-series photometric observations in the earliest stages of superoutbursts of the extreme dwarf novae, AL Com and WZ Sge, which started on 2001 May after the 6 years quiescence and on 2001 July after the 23 years quiescence,…

We present the results of U-band and multi-color photometry during the 2001 superoutburst of WZ Sagittae. Our 10 nights of U-band photometry span the time interval from HJD 2452118 to 2452197 while our multi-color observations range from…

We have found the first convincing evidence for spiral structure in the accretion disc of a close binary. The eclipsing dwarf nova binary IP Peg, observed during the end phase of a rise to outburst, shows strong Balmer and Helium emission…

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…

We present seven separate Chandra observations of the 2001 superoutburst of WZ Sge. The high-energy outburst was dominated by intense EUV emission lines, which we interpret as boundary layer emission scattered into our line of sight in an…

We carried out an international spectroscopic observation campaign of the dwarf nova GW Librae (GW Lib) during the 2007 superoutburst. Our observation period covered the rising phase of the superoutburst, maximum, slowly decaying phase…

Observations at high spectral and temporal resolution are presented of the dwarf nova EX Dra in outburst. The disk seen in the He I line reconstructed by Doppler tomography shows a clear two-armed spiral pattern pointing to spiral shocks in…

We present spectroscopic observations of the black-hole binary V4641 Sagittarii, obtained between 4th July 2004 and 28th March 2005, which cover the minor outburst of the star in early July 2004 and quiescence variations on 19 nights…

The outbursts of the dwarf nova WZ Sagittae occur on timescales which are much longer than expected from the standard thermal viscous disc instability model, which correctly reproduces the outburst behaviour of many other dwarf novae. In…

We find that the quiescent accretion disk of U Gem has a complicated structure. Along to the bright spot originating in the region of interaction between the stream and the disk particles, there are also explicit indications of spiral…

We present high-speed spectroscopic observations of the intermediate polar DQ Herculis. Doppler tomography of two He I lines reveals a spiral density structure in the accretion disc around the white dwarf primary. The spirals look very…