Pierre Kervella
INTERFEROMETRY AND ASTEROSEISMOLOGY OF MAIN SEQUENCE STARS (Poster)

INTERFEROMETRY AND ASTEROSEISMOLOGY OF MAIN SEQUENCE STARS

Pierre Kervella
LESIA, Observatoire de Paris

The interferometric measurement of the angular diameter of a number of nearby main sequence (MS) stars with the VLTI Test Instrument VINCI has allowed to retrieve their linear radii within 1-2% or better, thanks to their accurate Hipparcos parallaxes.

For several stars ($\alpha$ Cen A & B, Procyon A, $\delta$ Eri, $\xi$ Hya, $\eta$ Boo), asteroseismic oscillation frequencies are also available, in addition to the classical photometric and spectrographic observations. The combination of these data allows to constrain precisely the evolutionary status of each star (mass, internal structure and age). The figure below shows a comparison of different evolutionary tracks for Procyon A in the HR diagram. The interferometric measurement reduces significantly the classical error domain (rectangular box) to the shaded parallelogram. Model $a$ fits the observed large frequency spacing the best. It corresponds to a mass of 1.42M$_{\odot}$ and an age of 2.3Gyr.

High accuracy interferometric measurements from the VLTI combined with SIM or GAIA parallaxes will enable a great improvement of our understanding of the internal structure and evolution of MS stars. I will give a panorama of the nearby MS stars whose diameter is already within reach of such measurements with the VLTI.