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Session 77 - Binary Stars.
Display session, Wednesday, January 15
Metropolitan Ballroom,
The fainter component of the visual binary BD+33 1646 (Vys 250) has been found to be a double-lined spectroscopic binary. All three components of the system show strong and variable emission at H\alpha, with the equivalent width of the line increasing with decreasing brightness of the component. For all three stars the H\alpha emission profile shows central absorption. The brighter visual component flared strongly on JD2450210.61 with a tripling of the H\alpha equivalent width. Magnitude differences for the visual pair taken from CCD guider frames show probably real variations of a few tenths of a magnitude on other nights. The orbital elements for the fainter component are: P 6.2096 \pm 0.006 days e 0.043 \pm 0.16 T 2449619.8 \pm 0.4 ømega 79 \pm 20 degrees K1 40.2 \pm 0.5 km/sec K2 62.4 \pm 0.8 km/sec The large mass functions for the components, 0.42 and 0.27 solar masses, with spectral types of roughly M2 and M3, may indicate that eclipses are possible. They have not yet been observed by us.
