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Astron. Astrophys. 338, 933-946 (1998)

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5. Conclusion

Phase-resolved HST/GHRS observations of AM Her in a high state have revealed a wealth of previously unobserved details.

  1. We measure a column density [FORMULA] from the interstellar [FORMULA] absorption profile. There is no evidence for a phase-dependence of the absorption column. The present high state spectra also show no evidence for photospheric absorption lines from the white dwarf atmosphere other than shallow [FORMULA].

  2. We confirm our previous findings that the UV continuum flux modulation is due to a hot spot on the white dwarf and we successfully fit the observed light curve, deriving an upper limit on the spot size of [FORMULA]. However, a smaller and hotter spot can not be excluded.

  3. The absence/weakness of strong Lyman absorption lines in our GHRS data as well as in the ORFEUS-I data can be understood if the hot spot radiates as a blackbody. The contribution of the unheated parts of the white dwarf is sufficient to explain the shallow [FORMULA] absorption in the GHRS spectra.

  4. The Doppler tomograms computed from the emission lines show that, while the narrow emission of Si IV originates from the heated face of the secondary, the narrow emission of N V must originate from material between [FORMULA] and the centre of mass. A promising way to keep material co-rotating with the binary is a magnetic prominence located on the secondary star near the [FORMULA] point.

  5. For a distance [FORMULA] pc, the mass of the white dwarf in AM Her is [FORMULA].

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© European Southern Observatory (ESO) 1998

Online publication: September 17, 1998
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