The Relative Contributions to the Near‐Infrared Emission in Short‐Period Cataclysmic Variables

We present phase-resolved near-infrared broadband photometry of four short-period cataclysmic variables (HU Aqr, WZ Sge, TY Psc, and V592 Cas). Coupled with ultraviolet and optical data obtained from the literature, we have modeled the spectral energy distributions of these four cataclysmic variables, as well as that of the twin of WZ Sge, AL Com. The secondary stars contribute no more than 20%-50% of the near-infrared flux except for the polar HU Aqr, where the secondary contributes ~75% of the near-infrared flux. For the systems located above the orbital period minimum, the temperatures of the secondary stars match those for the expected main-sequence secondary stars. However, our modeling places WZ Sge below the orbital period minimum and shows it containing a secondary star of less than 1700 K—the coldest "star" yet identified.