High‐State Observations of the Eclipsing AM Herculis Object UZ Fornacis

Abstract

We present high-speed optical photometric observations of the eclipsing AM Her object UZ For that were obtained during 1995 February and October at the Cerro Tololo Inter-American Observatory. On both occasions, UZ For was in its high-luminosity state. In 1995 February, UZ had peak visual magnitude mV ≈ 15.9 ± 0.1 mag, which is roughly 0.5-1 mag brighter than previous reports of its high-state brightness level. In 1995 October, UZ For had peak magnitude mV ≈ 16.75 ± 0.25 mag, which is more similar to earlier reports of its high-state brightness level. The 1995 February light curves and eclipses are different in appearance from those for the lower luminosity states of UZ For reported in the literature. The eclipses are, however, similar to those of other AM Her systems, e.g., they are similar in shape to the eclipses of RE 2107-05 (HU Aqr) and to the ultraviolet eclipses of UZ For. The significance of the last statement is that in both of these systems, the accretion stream contributes a significant fraction of the overall luminosity of the system. In the low-luminosity state of UZ For, the accretion hot spot and the white dwarf photosphere dominate the optical emission. Here, we conclude that in the high-luminosity state, the accretion stream makes a significant contribution (and sometimes dominates) the optical emission from UZ For.