We explore the possible evolutionary status of the primary component of the binary 85 Pegasi , listed as a target for asteroseismic observations by the MOST satellite .
In spite of the assessed ‘ subdwarf ’ status , and of the accurate distance determination from the Hipparcos data , the uncertainties in the metallicity and age , coupled with the uncertainty in the theoretical models , lead to a range of predictions on the oscillation frequency spectrum .
Nevertheless , the determination of the ratio between the small separation in frequency modes , and the large separation as suggested by Roxburgh ( 2004 ) , provides a very good measure of the star age , quite independent of the metallicity in the assumed uncertainty range .
In this range , the constraint on the dynamical mass and the further constraint provided by the assumption that the maximum age is 14 Gyr limit the mass of 85 Peg A to the range from 0.75 to 0.82 M _ { \odot } .
This difference of a few hundreths of solar masses leads to well detectable differences both in the evolutionary stage ( age ) and in the asteroseismic properties .
We show that the age determination which will be possible through the asteroseismic measurements for this star is independent either from the convection model adopted or from the microscopic metal diffusion .
The latter conclusion is strengthened by the fact that , although metal diffusion is still described in an approximate way , recent observations suggest that the real stars suffer a smaller metal sedimentation with respect to the models .