THE FIRST THREE PLANETS
Geoffrey W. Marcy and R. Paul Butler
San Francisco State University
Department of Physics and Astronomy
San Francisco, CA 94132
Berkeley, CA 94720
Copyright: Stuart Kingsley
The first three extrasolar planets orbiting Solar-like stars have recently been discovered. All three were inferred from a periodicity in the optical Doppler measurements of their host stars, indicating a reflex motion in response to the gravitational force exerted by the planets. From such measurements and standard Newtonian physics, one may infer the orbital period and value of Mpl.(sin i) for the planet (where 'Mpl' is its mass and 'i' is orbital inclination). The three planets discovered thus far have Mpl.(sin i) of 0.46, 2.5 and 6.5 Mjup, and orbital periods of 4.2, 117 and 1100 days, respectively. The most massive planet (around 70 Vir) has an eccentricity, e = 0.38, larger than any in our Solar System, and one (around 51 Peg) has an orbital radius of 0.05 AU which is smaller than any in our Solar System. A general theory for the formation of planets must include these new characteristics.