PHOTOMETRIC AND H-ALPHA OBSERVATIONS OF LSI-DEGREES-303 - DETECTION OF A SIMILAR-TO-26-DAY V-BAND AND JHK-BAND MODULATION(61)

We present new optical and infrared photometric observations and high resolution Ha spectra of the periodic radio star LSI +61-degrees-303. The optical photometric data set covers the time interval 1985-1993 an d amounts to about a hundred nights. A period of approximately 26 days is found in the V band. The infrared data also present evidence for a similar periodicity, but with higher amplitude of variation (0.2m). T he spectroscopic observations include 16 intermediate and high dispers ion spectra of LSI +61-degrees-303 collected between January 1989 and February 1993. The Ha emission line profile and its variations are ana lyzed. Several emission line parameters - among them the Halpha EW and the width of the Halpha red hump - change strongly at or close to rad io maximum, and may exhibit periodic variability. We also observe a si gnificant change in the peak separation. The Halpha profile of LSI +61 -degrees-303 does not seem peculiar for a Be star. However, several of the observed variations of the Halpha profile can probably be associa ted with the presence of the compact, secondary star.