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P. Barai, D. R. Gies, E. Choi, V. Das, R. P. Deo, W. Huang, K. Marshall, M. V. McSwain, C. Ogden, A. Osterman, R. L. Riddle, J. L., Jr Seymour, D. W. Wingert (CHARA, GSU), A. B. Kaye (Applied Physics Division, LANL), G. J. Peters (Space Sciences Center, USC)
We present an investigation of the H\alpha emission line variations observed in the massive Algol binary, RY~Per. We used the observed optical spectra to calculate new radial velocity data for the secondary and high dispersion UV spectra for the primary. We present the revised orbital elements and an estimate of the primary's projected rotational velocity. We used a Doppler tomography algorithm to reconstruct the individual primary and secondary spectra in the region of H\alpha, and the latter was subtracted from each of our observations to obtain profiles of the primary and its disk alone. Our H\alpha observations of RY~Per show that the mass gaining primary is surrounded by a persistent but time variable accretion disk. The outside-of-eclipse profile has weak, double-peaked emission flanking a deep central absorption. It was found that these properties can be reproduced by a disk model that includes the absorption of photospheric light by the band of the disk seen projected against the face of the star. We developed a new method to reconstruct the disk surface density distribution from the ensemble of H\alpha profiles observed around the orbit, and this method accounts for the effects of disk occultation by the stellar components, the obscuration of the primary by the disk, and flux contributions from optically thick disk elements. The resulting surface density distribution is elongated along the axis joining the stars, in the same way as seen in hydrodynamical simulations of gas flows that strike the mass gainer near the trailing edge of the star. This type of gas stream configuration is optimal for the transfer of angular momentum, and we show that rapid rotation is also found in other Algols that have passed through a similar stage.
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The author(s) of this abstract have provided an email address for comments about the abstract: barai@chara.gsu.edu
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Bulletin of the American Astronomical Society, 35#5
© 2003. The American Astronomical Soceity.