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R. L. Riddle (Iowa State University)
The Struve-Sahade Effect is a phenomenon observed in massive binary stars where the spectral lines of the secondary star are enhanced when approaching the observer and weakened when receding. This effect has been measured in binary systems for over one hundred years, but an analytical model that explains it has yet to be found. This work represents the first attempt to observe the Struve-Sahade Effect in a comprehensive manner; all previous works either observed it in passing as part of another project or used archival data. The preliminary results that we present herein are surprising, in that six of the seven stars observed were expected to demonstrate the SSE as they have in the past. Instead, we find that only two of the stars observed show a strong SSE, with the others showing little or no SSE. This implies that the SSE is variable as a function of epoch as well as of phase, a fact not explained in any of the models presented for the Effect.
The driving reason to study the Struve-Sahade Effect is to determine what, if any, changes to the derived physical parameters of the star can arise. Massive binary stars are critical to our understanding of the upper left corner of the Hertzsprung-Russell diagram, as they are objects where we can actually measure their components and compare them to stellar structure and evolution theory. Errors in the measurements, and the derived physical parameters, can have a wide ranging effect in astrophysics, so any possible complications due to winds or gas in the systems need to be examined and understood.
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The author(s) of this abstract have provided an email address for comments about the abstract: riddle@iastate.edu