ARRAY CONFIGURATIONS FOR A SPACE INFRARED NULLING INTERFEROMETER DEDICATED TO THE SEARCH FOR EARTHLIKE EXTRASOLAR PLANETS

Recent studies show that an infrared nulling interferometer dedicated to the detection and spectroscopy of exoplanetary systems must fulfill three main requirements. It must provide very strong suppression of t he Fight originating from tile target star and good spectral coverage (from 6 to 18 mu m) with a fixed baseline and must be able to distingu ish planets from local dust disc emission without any ambiguity. We pr esent here a solution with five 1.5 m class telescopes deployed in an elliptical array that meets all these constraints. The telescope array , whose dimensions are about 50 by 25 m, has been optimized so that th e exozodiacal emission is strongly estinguished, very weakly modulated by rotation about the line of sight, and concentrated at a few even f requencies. The planet's signal, in contrast, is strongly modulated at many distinctive frequencies, A simple cross-correlation method recov ers a single image of a solar system twin al 10 pc distance after abou t 30 hr of integration time, The spectroscopy of the planets can then be undertaken with the same baseline and would reveal absorption featu res of water, ozone, and carbon dioxide for an Earthlike planet at 10 pc in less than 1 mo. (C) 1997 Academic Press.