ECLIPSE MAPPING OF THE ACCRETING MAGNETIC WHITE-DWARF IN DP-LEONIS WITH HST

We present time-resolved ultraviolet spectrophotometry of the AM Her s ystem DP Leo (E1114+182), obtained with the Faint Object Spectrograph on the Hubble Space Telescope (HST) in 1991 October. During this perio d, the binary was in a low-activity state. Complementary optical spect rophotometry and spectropolarimetry were obtained in 1991 October and December, as well as in 1992 April when the object had entered a high- accretion state. The HST spectrophotometry reveals two UV-emitting com ponents-a hot ''spot'' (T approximately 50,000 K, very approximately) near the magnetic pole into which most material is accreted, and the w hite dwarf photosphere (T approximately 16,000 K), which dominates whe n the spot is not in view. Both components appear as rapid and gradual components in the ingress and egress of secondary eclipse, the latter indicating a normal white dwarf radius of 0.8 x 10(9) cm. The fractio nal area of the spot (f approximately 0.006) implied by the eclipse da ta is consistent with the observed UV flux and a minimum distance of 3 80 pc and is similar to those found in other AM Her systems. The nearl y identical eclipse light curves from the HST and earlier optical obse rvations imply that the UV-emitting reprocessing area is not more exte nded than the cyclotron source of optical radiation in the accretion f unnel. The timing of the onset of the bright phase indicates that the spot leads the secondary in orbital azimuth by approximately 3-degrees .