EXTRASOLAR PLANETS IN DOUBLE AND MULTIPLE STELLAR SYSTEMS

A. Eggenberger, S. Udry, M. Mayor, G. Chauvin, B. Markus,
J.-L. Beuzit, A.-M. Lagrange, T. Mazeh, S. Zucker, D. Segransan

The majority of nearby G and K dwarfs belong to double or multiple
stellar systems, making these a common environment in which planets
may form. But close binaries are systematically rejected from most
radial velocity searches for extrasolar planets because they present
observational difficulties. Planet formation and survival in binaries
is thus a poorly known issue, though interesting in several aspects.
In particular, stellar duplicity could be used to test planet
formation models, and possibly discriminate between them. For a few
years we have been conducting two observational programmes aiming at:
(1) quantifying the occurrence of extrasolar planets in close binaries,
and (2) quantifying the global effect of stellar duplicity on planet
formation and survival for binaries with various separations. In this
contribution we will present interesting results from these two
programmes which are nearing completion.