Infrared spectroscopy of cataclysmic variables -- II. Intermediate polars

Abstract
We present infrared (0.97–2.45 μm) spectra of the intermediate polars PQ Gem (RE 0751 + 14), BG CMi and EX Hya. The spectra show strong Paschen, Brackett and He i emission lines from the accretion disc/stream. The infrared continua of PQ Gem and BG CMi can be represented by blackbodies of temperatures 4500 and 5100 K, respectively, or by power laws of the form fvv0.6,0.9, respectively, and show no evidence of secondary star features. The continuum of EX Hya is dominated by water bands from the red dwarf secondary star, which has a spectral type of ∼ M3. Despite showing circular polarization, PQ Gem and BG CMi show no evidence for cyclotron humps, and hence we are unable to measure their magnetic field strengths; any cyclotron emission present must contribute less than ∼ 3 per cent of the infrared continuum flux.
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