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K. E. Belle, S. B. Howell (Planetary Science Inst.), E. M. Sion (Villanova Univ.), K. S. Long (STScI)
EX Hydrae is a unique intermediate polar (IP) with a white dwarf spin period close to the orbital period; Pspin/Porb=0.68 for EX Hya compared with Pspin/Porb~.1 for other IPs. We have recently shown that the current IP model, in which magnetic accretion occurs from the inner edge of an annular accretion disk, does not necessarily hold true for EX Hya. The unique spin equilibrium state of EX Hya results in a partially corotating accretion disk which allows material at the outer edge of the disk to become magnetically controlled. Here we report on HST/STIS data that was obtained as part of a large coordinated multi-wavelength campaign. The six orbits of time-tagged, high resolution, ~.02Å/pixel, spectra provides an excellent opportunity to study the UV properties of this system. We review our analysis of the narrow and broad emission lines present in the UV spectra and show that the broad lines likely originate from the accretion curtains while the narrow components are formed close to the white dwarf surface. We also present a new analysis of the continuum flux by fitting theoretical accretion disk and white dwarf models created by TLUSTY and SYNSPEC to the UV spectra.
We would like to thank the director of the Hubble Space Telescope for the allocation of Director's time to participate in the EX Hydrae multi-wavelength campaign. This research was partially supported by NASA grant NAG5-8644 and HST grant GO-08807.01-A to SBH.
The author(s) of this abstract have provided an email address for comments about the abstract: keb@psi.edu
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Bulletin of the American Astronomical Society, 34
© 2002. The American Astronomical Soceity.