We discuss the nature of V Sagittae and T Pyxidis, two enigmatic blue variable stars commonly classed among the cataclysmic variables. These stars have bolometric luminosities in the range 36(1-50) # 10 ergs s Ϫ1 , far exceeding that of any accretion-powered cataclysmic variable. They also show extremely blue colors ( and after dereddening) and orbital light curves that are quite similar and yet are3 not seen in any normal cataclysmic variable. But in all these respects, as well as in the rich and highly excited emission-line spectrum, the stars provide a good match for the newly discovered class of "supersoft" X-ray binaries, probably powered by quasi-steady nuclear burning of accreted gas on a white dwarf. Both stars show photometric waves at the orbital period. V Sge also shows a deep minimum, a true eclipse of the accretion disk arising from fairly high binary inclination. T Pyx is nearly face-on (probably ), which results ini∼10 -20 narrow lines and a low amplitude for the orbital signal. T Pyx shows a very stable photometric wave at P ϭ days, but interpretation of this is hampered by another transient signal at 0.1098 days. This might be 0.076227 construed as evidence for a magnetic white dwarf. X e f f stars are now known (Greiner 1996

A B S T R A C TWe present a spectrophotometric study of short-term optical variability in the quiescent black hole X-ray transient V404 Cyg. This includes two nights of high-time-resolution Ha spectroscopy with which we resolve much of the time variability, and a further six nights of archival spectroscopy with lower time resolution but higher spectral resolution. We find significant variability in most of the data considered, with both the Ha line and the continuum often varying in a correlated way. This includes both dramatic flares lasting a few hours in which the line flux nearly doubles and lower-level flickering. The strongest flares involve development of asymmetry in the line profile, with the red wing usually strongest independent of orbital phase. It is unclear why this is the case, but we discuss several possible explanations. We consider the energetics of the flares and compare with plausible models including chromospheric activity on the companion star, local magnetic reconnection events within the disc and varying irradiation from close to the black hole. Based on the line profile changes during the flares, we conclude that the most likely origin for the variability is variable photoionization by the central source, although local flares within the disc cannot be ruled out.

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We present new multicolour (UBVRCIC) photometric observations of classical symbiotic stars, EG And, Z And, BF Cyg, CH Cyg, CI Cyg, V1329 Cyg, TX CVn, AG Dra, Draco C1, AG Peg, and AX Per, carried out between 2007.1 and 2011.9. The aim of this paper is to present new data of our monitoring programme, to describe the main features of their light curves (LC) and to point problems for their future investigation. The data were obtained by the method of the classical photoelectric and CCD photometry.

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