Spectroscopic Investigations of Massive Binaries

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AST-0205297PI GiesThe majority of the most massive stars are born in close pairs that are destined to interact over their lifetime. The influence of a companion can dramatically alter the evolutionary paths of the stars: the mass donors can be stripped down to a fraction of their original size while the mass gainers can become rejuvenated as more massive and luminous stars. These altered stars will eventually explode as peculiar supernovae, and their remnants dominate the appearance of the high energy universe (as massive X-ray binaries containing neutron stars and black holes). Although the starting and end-points of binary evolution are understood the processes that forge the intermediate stages are still mysterious, and great uncertainties surround the issues of mass and angular momentum transfer and loss. This project will be an investigation of these processes at various stages in the evolutionary drama through spectroscopic studies of a number of key systems. The first part is a survey of two dozen targets for new binaries with hard to detect companions. The second section is an orbital analysis of the H a emission flux formed in the circumstellar gas in two currently interacting systems. The third part examines the link between mass transfer and the spin up of rapidly rotating stars, and includes a hunt for faint post-mass transfer companions of Be stars. The final component is a joint H a -X-ray study of mass transfer in massive X-ray binaries as documented in extensive H a spectroscopy obtained with the KPNO Coude Feed Telescope.***