HST/FOS Eclipse mapping of IP Pegasi in outburst

Abstract

IP Pegasi is a deeply eclipsing dwarf nova (P_orb= 3.8 hr) which shows 1-2 weeks-long, ≃ 2 mag outbursts every 60-120 days. During outbursts, tidally induced spiral shocks form in its accretion disc as the disc expands and its outer parts feel more effectively the gravitational attraction of the companion star (Steeghs, Harlaftis & Horne 1997). Here we present the first results of a time-resolved ultraviolet (UV) spectral mapping experiment of IP~Pegasi 9-13 days after onset of the May 1993 outburst.