Absolute dimensions of TT hydrae

Abstract

The photometric elements of the Algol type binary TT Hydrae derived by the authors from their UBV observations during 1973-77 have been combined with the spectroscopic elements given by Sanford (1937) and Sahade and Cesco (1946) to obtain the absolute dimensions of the system. It is found that the spectroscopic orbital elements given by Sanford represent the evolutionary status of the secondary component better than those of Sahade and Cesco. The primary appears to be an Al v main sequence star of mass ~ 3 to 4m_⊙ and radius ~2.3R_⊙. The secondary fills its Roche lobe; it can be represented by a K0III star of mass ~0.8m_⊙ and radius ~6.0Rm_⊙. Better spectroscopic data are needed for confirmation of these results.