Abstract

The EVRIS experiment is an exploratory mission devoted to stellar seismology. It will observe approximately ten bright stars, for 20 days each, during the cruise of the Russian MARS 94 mission. The photometer will be able to detect amplitudes of modes as small as a few 10−6 magnitude. Some objects of masses lower than the solar one will allow to test the thermodynamics.

EVRIS est la première expérience dévouée à la sismologie des étoiles. Elle sera lancée par la mission Russe MARS 94. Elle observera une dizaine d'objets, chacun pendant une vingtaine de jours, avec un seuil de détection de quelques 10−6 magnitude. Plusieurs étoiles de masse plus faible que celle du Soleil devraient permettre des tests significatifs de leur thermody-namique.

An exploratory instrument for asteroseismology.

Scientific objectives and strategy.

After the success of detection, measurements and interpretation of the eigemodes of the Sun, it is tempting to try to achieve similar progress on other stars and to allow for a comparative and differential study of the seismical stellar behavior.

The major difficulties when going from the Sun to stars is the lack of photons and the lack of spatial resolution. The rationale for such an aim has already been developed several times (i.e. Hudson et al. 1986, Praderie et al. 1988).

The need to go to space has also been extensively documented (see i.e. Mangeney and Praderie 1984, Hudson et al. 1986, Baglin 1990, Weiss 1992).