Bibcode
DOI
Patterson, Joseph; Kemp, Jonathan; Shambrook, Anouk; Thorstensen, John R.; Skillman, David R.; Gunn, Jerry; Jensen, Lasse; Vanmunster, Tonny; Shugarov, Sergei; Mattei, Janet A.; Shahbaz, Tariq; Novak, Rudolf
Bibliographical reference
The Publications of the Astronomical Society of the Pacific, Volume 110, Issue 746, pp. 380-395.
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4
1998
Citations
93
Refereed citations
81
Description
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)x10^36 ergs s^-1,
far exceeding that of any accretion-powered cataclysmic variable. 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 and yet are
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 i~10^deg-20^deg), which
results in narrow lines and a low amplitude for the orbital signal. T
Pyx shows a very stable photometric wave at P=0.076227 days, but
interpretation of this is hampered by another transient signal at 0.1098
days. This might be construed as evidence for a magnetic white dwarf.