T. Mazeh

SS 433: Intensive 4 month light curves

Photometry covering 100 nights during 1979 July--November is reported; in an unfiltered band (effectively 5200--8000 A), in a V band; in a far-red band; and with a few measures in B. We find (1) correlation with the 13 day period of Crampton, Cowley, and Hutchings, in the form of a double-peak light curve; and (2) a more tentative connection with the 164 day precession period (Margon et al.), suggested by a broad light minimum near a critical phase in the long cycle.

A Radial-Velocity Search for Brown Dwarfs and the Low-Mass Companion of HD114762

For the past four years we have monitored the radial velocities of a sample of 24 M dwarfs in order to search for low-amplitude periodic velocity variations that might indicate orbital motion due to low-mass companions. To monitor systematic errors we chose for every star of the sample a comparison star, to be observed next to its project star. We have not yet found a convincing evidence for a periodic modulation in the data of the M stars, nor in those of the comparison stars. However, a few candidates for low-amplitude radial-velocity variations can be seen in the data. The best case for a low-mass companion discovered using radial velocities is still HD114762; we briefly report on the status of our study of this IAU standard star. We conclude that substellar companions may be rare compared to stellar companions, but there exist more than one candidate for brown dwarf companions.