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Session 77 - Binary Stars.
Display session, Wednesday, January 15
We report on FOS spectropolarimetry observations obtained in June 1996 in the 1600-2300Å\ region of the interacting binaries V356 Sgr and TT Hya. Both systems show non-stellar continuum in the ultraviolet, and broad emission lines during total eclipse. V356 Sgr consists of an early B star that exhibits a B2II spectrum accreting matter from a Roche-lobe filling A2II star. The orbital period is 8.896 days. V356 Sgr spectropolarimetry was obtained during totality (phase 0.993), and at binary phase 0.32. Linear polarization at the shortest wavelengths changes from around 1inside eclipse. The emission lines and nonstellar continuum from V356 Sgr lie predominately at shorter wavelengths, so any correlation of polarization with spectral features is limited. TT Hya has a period of 6.95 days, and consists of a B9.5 primary and a G9/K1 III/IV secondary. Strong emission lines are present in this wavelength region in TT Hya, as is a non-stellar continuum. Two independent observations of TT Hya were obtained during a single primary eclipse. TT Hya shows a considerable linear polarization in the non-stellar continuum (up to 20-30the shortest wavelengths), and strong correlation of polarization with emission lines. The emission lines are depolarized with respect to the continuum, and polarization position angle rotations are seen across spectral lines. A detailed description of the spectropolarimetric observations are presented along with models interpreting the observations.
Program listing for Wednesday