Several attempts have been made to detect solar-like oscillations in the G0 IV star $ η $ ~Boo .
We present here new observations on this star simultaneously conducted with two spectrographs : Coralie mounted on the 1.2-m Swiss telescope at the ESO La Silla Observatory ( Chile ) and Elodie based on the 1.93-m telescope at the Observatoire de Haute Provence ( France ) .
In total , 1239 spectra were collected over 13 nights .
The power spectrum of the high precision velocity time series clearly presents several identifiable peaks between 0.4 and 1.0 mHz showing regularity with a large and small separations of \Delta \nu = 39.9 \mu Hz and \delta \nu _ { 02 } = 3.95 \mu Hz respectively .
Twenty-two individual frequencies have been identified .
Detailed models based on these measurements and non–asteroseismic observables were computed using the Geneva evolution code including shellular rotation and atomic diffusion .
By combining these seismological data with non–asteroseismic observations , we determine the following global parameters for $ η $ ~Boo : a mass of 1.57 \pm 0.07 M _ { \odot } , an age t = 2.67 \pm 0.10 Gyr and an initial metallicity ( Z / X ) _ { \mathrm { i } } = 0.0391 \pm 0.0070 .
We also show that the mass of $ η $ Boo is very sensitive to the choice of the observed metallicity , while the age of $ η $ Boo depends on the input physics used .
Indeed , a higher metallicity favours a higher mass , while non–rotating models without overshooting predict a smaller age .