Narrow-Angle Astrometry with the Space Interferometry Mission: The Search for Extra-solar Planets. I. Detection and Characterization of Single Planets

摘要

(abridged) We present results from a detailed set of end-to-end numericalsimulations of SIM narrow-angle astrometric measurements and data analysis toillustrate the enormous potential that SIM has for the discovery andcharacterization of planets outside the Solar System. Utilizing a templateobserving scenario, we quantify SIM sensitivity to single planets orbitingsingle normal nearby stars as function of measurement errors and properties ofthe planet: SIM will detect over 95% of the planets with periods between a fewdays and the 5-year nominal mission lifetime that produce astrometricsignatures $sim 2.2$ times larger than the single-measurement accuracy. Weprovide accuracy estimates of full-orbit reconstruction and planet massdetermination: at twice the discovery limit, orbital elements will bedetermined with a typical accuracy of 20-30%; the astrometric signature must be$sim 10$ and $sim 15$ times the minimum signal required for detection toderive mass and inclination angle estimates accurate to 10%. We quantify theimpact of different observing strategies on the boundaries for secure detectionand accurate orbit estimation: the results scale with the square root of boththe number of observations and the number of reference stars. We investigateSIM discovery space, to gauge the instrument ability in detecting very low-massplanets: around the nearest stars, SIM will find planets as small as Earth, ifthey are present. Some of these might be orbiting inside the parent star'sHabitable Zone. (abridged)