2 GALACTIC SUPERSOFT X-RAY BINARIES - V-SAGITTAE AND T-PYXIDIS

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 (1-50) x 10(36) ergs s(-1), far exceeding that of any accretion-powered cataclysmic variabl e. They also show extremely blue colors (B - V = -0.3 and U - B = -1.3 after dereddening) and orbital light curves that are quite similar an d pet are not seen in any normal cataclysmic variable. But in all thes e respects, as well as in the rich and highly excited emission-line sp ectrum, the stars provide a good match for the newly discovered class of ''supersoft'' X-ray binaries, probably powered by quasi-steady nucl ear burning of accreted gas on a white dwarf. Both stars show photomet ric waves at the orbital period. V Sge also shows a deep minimum, a tr ue eclipse of the accretion disk arising from fairly high binary incli nation. T Pyx is nearly face-on (probably i similar to 10 degrees-20 d egrees), which results in narrow lines and a low amplitude for the orb ital signal. T Pyx shows a very stable photometric wave at P = 0.07622 7 days, but interpretation of this is hampered by another transient si gnal at 0.1098 days. This might be construed as evidence for a magneti c white dwarf.