The Hyades K2V+WD system 471 Tau is a prototype post-common envelope system and a likely cataclysmic binary progenitor .
We present 10 days of nearly continuous optical photometry by the MOST ( Microvariability & Oscillations of STars ) satellite and partly simultaneous optical spectroscopy from DDO ( David Dunlap Observatory ) of the binary .
The photometric data indicate that the spot coverage of the K dwarf component was less than observed in the past , suggesting that we monitored the star close to a minimum in its activity cycle .
Despite the low spot activity , we still detected seven flare-like events whose estimated energies are among the highest ever observed in V471 Tau and whose times of occurrence do not correlate with the binary orbital phase .
A detailed O - C analysis of the times of eclipse over the last \sim 35 years reveals timing variations which could be explained in several ways , including perturbations by an as-yet-undetected third body in the system or by a small orbital eccentricity inducing slow apsidal motion .
The DDO spectra result in improved determinations of the K dwarf projected rotation velocity , V _ { K } \sin i = 92 km s ^ { -1 } , and the orbital amplitude , K _ { K } = 150.5 km s ^ { -1 } .
The spectra also allow us to measure changes in H \alpha emission strength and radial velocity ( RV ) variations .
We measure a larger H \alpha velocity amplitude than found previously suggesting that the source of the emission in V471 Tau was less concentrated around the sub-white-dwarf point on the K star than had been observed in previous studies .