The Rotation Effect in the Radial-Velocity Curves of AI Dra and V505 Sgr
Session 47 -- Binary Stars
Display presentation, Thursday, June 15, 1995, 9:20am - 4:00pm

## [47.04] The Rotation Effect in the Radial-Velocity Curves of AI Dra and V505 Sgr

T.F. Worek (Community College of Allegheny County)

CCD spectra were obtained for the late B and early A type Algol binaries AI Dra and V505 Sgr during their May, 1991 primary eclipses using the coud\'{e}-feed telescope and spectrograph at KPNO . With these spectra, the Rossiter-McLaughlin rotation effect was observed in the radial-velocity curves of these stars. The least-squares fit to the rotation effect yielded projected rotational velocities of $85.6 \pm2.1$ and $131\pm2.8$ km\ $s^{-1}$ and barycentric velocities $+5.5 \pm 0.4$ and $-0.8 \pm 0.6$ km\ $s^{-1}$ for AI Dra and V505 Sgr, respectively. Compared to their synchronous values, AI Dra appears to be rotating slower while V505 Sgr is rotating faster than expected. The eclipse spectra were also inspected for signs of secondary and/or tertiary companions. The third star belonging to the V505 Sgr system was easily recognized thus confirming its discovery by Tomkin (1992, ApJ. 387, 631). No obvious absorption features directly attributed to the secondary in either system could be found. However, the CaK line in AI Dra was at times slightly distorted but this could be due to circumstellar contamination.