Joint Hα and X‐Ray Observations of Massive X‐Ray Binaries. I. The B Supergiant System LS I +65 010 = 2S 0114+650

We report on a three year spectroscopic monitoring program of the H-alphaemission in the massive X-ray binary LS I +65 010 = 2S 0114+650, which consistsof a B-supergiant and a slowly rotating X-ray pulsar. We present revisedorbital elements that yield a period of P=11.5983 +/- 0.0006 d and confirm thatthe orbit has a non-zero eccentricity e=0.18 +/- 0.05. The H-alpha emissionprofile is formed in the base of the wind of the B-supergiant primary, and weshow how this spectral feature varies on timescales that are probably relatedto the rotational period of the B-supergiant. We also examine the X-ray fluxesfrom the Rossi X-ray Timing Explorer All-Sky Monitor instrument, and we showthat the X-ray orbital light curve has a maximum at periastron and a minimum atthe inferior conjunction of the B-supergiant. We also show that the windemission strength and the high energy X-ray flux appear to vary in tandem ontimescales of approximately a year.Comment: accepted to ApJ, 19 pages including 6 figures and 3 table