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Session 22 - Binary Stars: New Generation Modeling Developments & Results.
Oral session, Tuesday, June 10
North Main Hall F/G,

[22.08] Simultaneous Fitting of Orbital Elements and Doppler Imaging of Spots Using Photometric and Spectroscopic Data

S. W. Mochnacki, P. D. Hendry (DDO)

We briefly review previous work on Doppler and photometric imaging of starspot distributions on close binary stars, particularly contact binaries. Difficulties involving standard spherical and cylindrical surface element distributions for imaging are discussed. The method of geodesic distribution binary synthesis (GDDSYN) is faster and more accurate for such work.

The Maximum Entropy regularisation method has been extended to include simultaneous photometry and spectroscopy. A further extension allows auxiliary parameters such as mass ratio and fill-out to be determined, as well as the radial velocity amplitude. The spectrum of third light contamination is also obtained, using theoretical spectrum synthesis for the binary as input. Accurate distances act as a powerful constraint on the fitting process.

The procedure has been applied by PDH to the system VW Cephei. The development of spots over a two year period has been studied. The fraction of the surface covered by spots appears to be be very large.

Future developments will be discussed. This type of approach is essential to obtain good models for cool, heavily-spotted binary systems.

Program listing for Tuesday