The mid-infrared spectrum of the short orbital period polar EF Eridani from the Spitzer Space Telescope

We present the first mid-infrared (5.5-14.5 μm) spectrum of a highly magnetic cataclysmic variable, EF Eridani, obtained with the Infrared Spectrograph (IRS) on the Spitzer Space Telescope. The spectrum displays a relatively flat, featureless continuum. A spectral energy distribution model consisting of a 9500 K white dwarf, an L5 secondary star, cyclotron emission corresponding to a B ≈ 13 MG white dwarf magnetic field, and an optically thin circumbinary dust disk is in reasonable agreement with the extant Two Micron AU Sky Survey (2MASS), Infrared Array Camera (IRAC), and IRS observations of EF Eri. Cyclotron emission is ruled out as a dominant contributor to the infrared flux density at wavelengths ≳3 μm. The spectral energy distribution longward of ∼5 μm is dominated by dust emission. Even longer wavelength observations would test the model's prediction of a continuing gradual decline in the circumbinary disk-dominated region of the spectral energy distribution.