Hipparcos Data Analysis of the Eclipsing Binary II UMa

Two light curve solutions for the close eclipsing binary II UMa, using Hipparcos data, are presented. The analysis was made using the PHOEBE program. The first solution was derived adopting the spectroscopic value q = 0.172 while the presence of third light was considered too. The second solution is based on the mass ratio value q = 0.13, derived by a q‐search. It was found that II UMa is an A sub‐class W UMa‐type binary, and belongs to a class of systems with very low mass ratio that is expected to evolve in a single rapidly rotating star.