Extrasolar Planets around Main Sequence Stars

The mass distribution of substellar companions exhibits a steep rise for masses below 5 MJ. Thus, the 14 companions having Msin i = 0.5 { 5 MJ are considered the best candidate planets around main sequence stars. The occurrence of such planets within 3 AU is 4%, but 2/3 of them orbit within just 0.3 AU. This \pile up" of planets near stars suggests that inward orbital migration occurred after formation. The planet candidates orbiting within 0.1 AU have nearly circular orbits, but all 9 orbiting outside 0.2 AU have e > 0.1, i.e., greater than that of Jupiter, eJUP = 0.048. Thus, eccentric orbits predominate for jupiter{mass companions from 0.2{2.5 AU, and may arise from gravitational interactions with other planets, stars, or the proto-planetary disk. The planet{bearing stars are systematically metal{rich, as is the Sun, compared to the Solar neighborhood. The occurrence of \brown dwarf" companions in the next higher mass decade, 5 { 50 MJ , is at most 1% within 3 AU, based on surveys of 600 stars. Thus, brown dwarfs represent a minimum in the mass function of companions, between the masses of stars and of planets.