IUE observations of the contact binary XY Leonis.

Abstract

IUE observations (FES light curves, LWR Mg II emission data, and an SWP spectrum) obtained on June 11, 1982 are reported for XY Leo. The Mg II fluxes were measured at two primary minima, one secondary minimum, and one orbital quadrature. The data are presented in tables and spectra and analyzed. The orbital-average relative flux f(Mg II)/f(bol) is found to be 0.000176 + or - 0.000006, indicating that the two components are equally covered with active regions, while the mean fluxes of the chromospheric Mg II and C II lines and the transition-region N V and C IV lines are shown to be similar to those of very-short-period G-K-type contact binaries.