We have revisited the calibration of the visual binary system \zeta Herculis with the goal to give the seismological properties of the G0 IV sub-giant \zeta Her A .
The sum of masses and the mass fraction are derived from the most recent astrometric data mostly based on the hipparcos ones .
We have derived the effective temperatures , the luminosities and the metallicities from available spectroscopic data and tycho photometric data and calibrations .
For the calculations of evolutionary models we have used updated physics and the most recent physical data .
A \chi ^ { 2 } minimization is performed to approach the most reliable modeling parameters which reproduce the observations within their error bars .
For the age of the \zeta Her binary system we have obtained t _ { \zeta Her } = 3 387 Myr , for the masses m _ { \zeta Her A } = 1.45 M _ { \odot } and m _ { \zeta Her B } = 0.98 M _ { \odot } , for the initial helium mass fraction Y _ { i } = 0.243 , for the initial mass ratio of heavy elements to hydrogen ( \frac { Z } { X } ) _ { i } = 0.0269 and for the mixing-length parameters \Lambda _ { \zeta Her A } = 0.92 and \Lambda _ { \zeta Her B } = 0.90 using the Canuto & Mazitelli ( [ 1991 ] , [ 1992 ] ) convection theory .
Our results do not exclude that \zeta Her A is itself a binary sub-system has been suspected many times in the past century ; the mass of the hypothetical unseen companion would be m _ { \zeta Her a } \loa 0.05 M _ { \odot } , a value significantly smaller than previous determinations .
A calibration made with an overshoot of the convective core of \zeta Her A leads to similar results but with a slight increase of \approx + 250 Myr for the age .
The adiabatic oscillation spectrum of \zeta Her A is found to be a complicated superposition of acoustic and gravity modes .
Some of these waves have a dual character .
This greatly complicates the classification of the non-radial modes .
For \ell = 1 the modes all have both energy in the core and in the envelope ; they are mixed modes .
For \ell = 2 , 3 there is a succession of modes with energy either in the core or in the envelope with a few mixed modes .
The echelle diagram used by the observers to extract the frequencies will work for \ell = 0 , 2 , 3 .
The large difference is found to be of the order of \overline { \Delta \nu _ { 0 } } \approx 42 \mu Hz , in agreement with the Martić et al .
( [ 2001 ] ) seismic observations .