The orbit and physical parameters of the previously unsolved eclipsing binary V432 Aur , discovered by Hipparcos , have been derived with errors better than 1 % from extensive Echelle spectroscopy and B , V photometry .
Synthetic spectral analysis of both components has been performed , yielding T _ { eff } and \log g in close agreement with the orbital solution , a metallicity [ Z/Z _ { \odot } ] = - 0.6 and rotational synchronization for both components .
Direct comparison on the theoretical L,T _ { eff } plane with the Padova evolutionary tracks and isochrones for the masses of the two components ( 1.22 and 1.08 M _ { \odot } ) provides a perfect match and a 3.75 Gyr age .
The more massive and cooler component is approaching the base of the giant branch and displays a probable pulsation activity with an amplitude of \Delta V =0.075 mag and \Delta rad.vel.=1.5 km sec ^ { -1 } .
With a T _ { eff } =6080 K it falls to the red of the nearby instability strip populated by \delta Sct and \gamma Dor types of pulsating variables .
Orbital modeling reveals a large and bright surface spot on it .
The pulsations activity and the large spot ( s ) suggest the presence of macro-turbulent motions in its atmosphere .
They reflect in a line broadening that at cursory inspection could be taken as indication of a rotation faster than synchronization , something obviously odd for an old , expanding star .