People involved at OAB: Bonifazi, Lolli.
The study of binary systems is of basic importance to derive fundamental stellar parameters (M, L, R) and therefore to test stellar structure and evolution. For this purpose we have collected light curves of many binary systems observed with the Loiano 60 and 152cm telescopes. We have also derived the precise timing of light minima of the eccentric systems DR Vul, V380 Cyg, RR Lyn, AK Her, ER Vul, BF Aur, exibiting apsidal motion that can be correlated to the mass distribution in the stellar interior. We have observed with the Loiano 152cm telescope the interesting W UMa-type systems RW Com and XY Leo along with the pre-CV NN Ser and the CV TT Ari. Spectra for NN Ser were also collected at the 6m BAT.
Light curve analyses are performed with the Wilson-Price program (Barone et al. 1988) based on the Wilson-Devinney (1971) model. After many tests of the code and some preliminary solutions we proceeded with the study of the binary star XY Leo. This very intriguing W UMa-type system - possibly a triple system - shows unequal maxima. This is explained by the presence of spots on the surface. One of the best solutions is showed in Fig.7, that displays the observed (open circles) and computed (solid line) light curves.
Figure 7:
Comparison of observations and solution model for XY Leo,
a W UMa binary star possibly consisting of a triple system.
Our team includes Guarnieri, Bartolini, Piccioni and Cosentino (Univ. Bologna), Beskin (SAO), Milano (Univ. Napoli) and Barone (Univ. Salerno).