DASCH DISCOVERY OF A POSSIBLE NOVA-LIKE OUTBURST IN A PECULIAR SYMBIOTIC BINARY
- Harvard-Smithsonian Center for Astrophysics, 60 Garden St, Cambridge, MA 02138 (United States)
We present photometric and spectroscopic observations of a peculiar variable (designated DASCH J075731.1+201735 or J0757) discovered from our DASCH project using the digitized Harvard College Observatory archival photographic plates. It brightened by about 1.5 mag in B within a year starting in 1942, and then slowly faded back to its pre-outburst brightness from 1943 to 1950s. The mean brightness level was stable before and after the outburst, and ellipsoidal variations with a period of P = 119.18 {+-} 0.07 days are seen, suggesting that the star is tidally distorted. Radial-velocity measurements indicate that the orbit is nearly circular (e = 0.02 {+-} 0.01) with a spectroscopic period that is the same as the photometric period. The binary consists of a 1.1 {+-} 0.3 M{sub Sun} M0III star, and a 0.6 {+-} 0.2 M{sub Sun} companion, very likely a white dwarf (WD). Unlike other symbiotic binaries, there is no sign of emission lines or a stellar wind in the spectra. With an outburst timescale of {approx}10 years and estimated B-band peak luminosity M{sub B} {approx} 0.7, J0757 is different from any other known classic or symbiotic novae. The most probable explanation of the outburst is hydrogen shell burning on the WD, although an accretion-powered flare cannot be ruled out.
- OSTI ID:
- 22037192
- Journal Information:
- Astrophysical Journal, Vol. 751, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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