Direct Detection of the L-Dwarf Donor in WZ Sagittae

Abstract

Analysis of a large set of phase-resolved $K$-band spectra of the cataclysmic variable WZ Sge shows that the secondary star of this system appears to be an L-dwarf. Previous $K$-band spectra of WZ Sge found that the CO overtone bandheads were in emission. We show that absorption from the ${}^{12}$CO${}_{(2,0)}$ bandhead of the donor star creates a dip in the ${}^{12}$CO${}_{(2,0)}$ emission feature. Measuring the motion of this feature over the orbital period, we construct a radial velocity curve that gives a velocity amplitude of K${}_{\mathrm{abs}}$ = 520 $\pm$ 35 km s${}^{-1}$, consistent with the previously published values for this parameter.

16 pages, 7 figures. Accepted for publication in the Astrophysical Journal

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• On the Radii of Brown Dwarfs Measured with AKARI Near-Infrared Spectroscopy
• A Near-Infrared Spectroscopic Study of the Accreting Magnetic White Dwarf SDSS J121209.31+013627.7 and its Substellar Companion
• Quantifying the Carbon Abundances in the Secondary Stars of SS Cygni, RU Pegasi, and GK Persei
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