Future Astrometry with ALMA to characterise extra-solar planet orbits

Abstract

The most complete catalogue of nearby stars (Gliese and Jarheiss, 1991) has been used to search for the stars whose photospheric thermal emission can be detected by the future millimeter array ALMA. We found that 446 nearby stars with spectral types ranging from A to M are detectable. A long-term astrometric observation programme (> 10 yr) of these stars with ALMA (theoretical astrometric precision = 0.1 milliarcsecond) would be sensitive to wobbles caused by the gravitational pull of possible unseen planets. Such a programme would probe minimum planetary masses as low as 0.1 Jupiter for an orbital period of 10 years. We provide histogrammes of these minimum masses and of ALMA integration times for these 446 ALMA stars.