NOAO >   Observing Info >   Approved Programs >   2013A-0422

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Proposal Information for 2013A-0422


PI: Geraldine J. Peters, University of Southern California, gjpeters@mucen.usc.edu
Address: Space Sciences Center/Dept. of Physics & Astronomy, 835 W. 37th Street, Los Angeles, CA 90089-1341, USA

CoI: Todd R. Vaccaro, St. Cloud State University
CoI: Robert E. Wilson, University of Florida

Title: Orbital and Systemic Parameters for Algol Binaries in the Field-of-View of the Kepler Spacecraft

Abstract: We propose observations of seven Algol-type binaries with the 4m Echelle spectrograph necessary for the interpretation of ongoing photometry from the \it Kepler spacecraft and archival \it Kepler data being analyzed for an approved NASA/ADAP project. These Algols are direct-impact systems (periods range from 1.3-4.5\rm^d) in which the gas stream strikes the photosphere of the gainer, producing a shock. The \it Kepler light curves reveal striking long and short-term variability never before seen in ground-based observations. Especially interesting is a long-term oscillation in the relative brightness of the quadrature light that we call L/T variability, which appears to be caused from a migrating variable hot spot. The \it Kepler photometry is being interpreted with an updated version of the Wilson & Devinney (WD) program. The KPNO spectra will supply \it critical input parameters (e.g. temperatures) and yield radial velocity curves from which we will determine the masses of the stars and absolute dimensions of the systems. Currently there are \it no published spectra of most of the program binaries, including WX Dra, the prototype L/T variable and our primary target. We request 4 nights of observing time to cover one orbital cycle in the binaries with the longest periods. This project will yield information on the detailed physics of mass transfer, especially the roles of accretion hot spots and magnetic fields, and also test the new WD program for future applications by others working with the \it Kepler database.


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