SIMBAD references

We present the first detection of the mass donor star in the cataclysmic variable WZ Sagittae. Phase-resolved spectroscopy reveals narrow Balmer emission components from the irradiated secondary star during the 2001 outburst. Its radial velocity curve indicates a systemic velocity of -72±3 km.s^–1 and an apparent velocity amplitude of K'₂=493±10 km.s^–1. Doppler tomography reveals a highly asymmetric accretion disk including a significant bright spot contribution 20 days into the outburst. We estimate the apparent primary radial velocity using the Hα tomogram and find K'₁=37±5 km.s^–1. Accounting for the likely systematic errors affecting both K₁ and K₂ measurements, we conservatively derive 493 km.s^–1<K₂<585 km.s^–1 and K₁<37 km.s^–1. The measured phase offset between bright spot eclipse and inferior conjunction of the secondary star brackets the allowed mass ratio (q=M₂/M₁) to lie between 0.040 and 0.075. These constraints imply a white dwarf with M₁>0.70 M_☉ and a low-mass secondary with M₂<0.11 M_☉. A nondegenerate mass donor, implying WZ Sge has not yet evolved through its minimum period, is therefore not ruled out by our observations. This would require an improved estimate of K₁.