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Close Binaries with Mass Transfer

F. Soydugan, PhD student of the Ege University of Izmir (Turkey) visiting researcher at OACt in 2003-2004, has studied spectroscopically some Algol systems. He has presented at the 13th Cool Star Workshop (), together with A. Frasca and S. Catalano, new high-resolution (R $\simeq$ 22000) optical spectra of three Algol binaries, namely KO Aql, S Equ and AT Peg, obtained with the echelle spectrograph of Catania Astrophysical Observatory. Thanks to the cross-correlation procedure, they were able to obtain, for the first time, radial velocity curves also for the cool secondary components of KO Aql and S Equ that allowed them to improve the physical parameters of the components of these binaries (Fig. 1.15). They have also measured, with a rather good accuracy (2-4 km/s), the rotational velocity of the hotter components of these three systems and found that, with the exception of AT Peg, the primary stars are rotating faster than the synchronization velocity, consistently with a mass transfer scenario. Preliminary results on the mass-transfer effects displayed by the H$\alpha$ and H$\beta$ extra-absorption/emission components are also discussed.

Figure: Radial velocity curves of the primary (filled circles) and secondary components (open circles) of KO Aql and S Equ and their best fits (solid and dashed lines).
\begin{figure}\centerline{\psfig{file=stars/fsoyduganf1a.ps,width=8cm}}
\centerline{\psfig{file=stars/fsoyduganf1b.ps,width=8cm}}\end{figure}

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Next: Stellar oscillations and asteroseismology Up: Magnetic activity and variability Previous: Evolution of stellar magnetic   Contents   Index
Innocenza Busa' 2005-11-14