Spectroscopic observations of the eclipsing polar MN Hya (RX J0929-24)

We present low-medium resolution optical spectroscopy of the eclipsing AM H er system MN Hya (RX J0929-24). We determine the magnetic field strength at the primary accretion region of the white dwarf to be 42 MG from the spaci ng of cyclotron features visible during phi similar to 0.4-0.7. From spectr a taken during the eclipse we find that the secondary has an M3-4 spectral type. Combined with the eclipse photometry of Sekiguchi, Nakada & Bassett a nd an estimate of the interstellar extinction we find a distance of similar to 300-700pc. We find unusual line variations at phi similar to 0.9: H alp ha is seen in absorption and emission. This is at the same point in the orb ital phase at which a prominent absorption dip is seen in soft X-rays.