University of Wisconsin

Space Astronomy Laboratory

ASTRO - 2

WUPPE

OBJECT: U Cepheus (U-CEP)
Other names: HD 5679
ID # 3306

UW Astronomer: Geoff Fox


U-Cep is a binary system located 1,000 light years away in the constellation of Cepheus. Cepheus is a circumpolar constellation located just west of Cassiopeia. Its stars' diameters are 2.9 times and 4.7 times the diameter of our Sun, with masses corresponding to 4.7 times and 1.9 times the mass of our Sun. The system's orbital revolution is just under 2.5 days, but it is gradually increasing due to the change in relative mass from the expanding secondary star to the bright primary star. This mass transfer occurs over the 6.5 million miles separating the two stars.