Determination of Masses and Other Properties of Extrasolar Planetary Systems with More than One Planet

Recent analysis of the Doppler-shift oscillations of the light from extrasolar planetary systems indicates that some of these systems have more than one large planet. In this case, it has been shown that the masses of these planets can be determined without the familiar ambiguity due to the unknown inclination angle of the plane of the orbit of the central star provided, however, that the star mass is known. A method is presented here that also determines a lower limit to the mass of this star from these observations. As an illustration, our method is applied to the Keck and Lick data for GJ 876.