Narrow-Angle Astrometry with the Space Interferometry Mission The Search for Extra-solar Pl.pdf

a r X i v : a s t r o - p h / 0 2 0 7 2 2 2 v 1 1 0 J u l 2 0 0 2 Narrow-Angle Astrometry with the Space Interferometry Mission: The Search for Extra-solar Planets. I. Detection and Characterization of Single Planets A. Sozzetti1,2,4 alex@ S. Casertano3 and R. A. Brown3 stefano@; rbrown@ and M. G. Lattanzi4 lattanzi@to.astro.it ABSTRACT A decade after the publication of the Hipparcos Catalogue, the Space Interfer- ometry Mission (SIM) will be capable of making selected high-precision astrometric measurements about three orders of magnitude more accurate than the Hipparcos survey. We present results from a detailed set of end-to-end numerical simulations of SIM narrow-angle astrometric measurements and data analysis to illustrate the enormous potential that SIM has for the discovery and characterization of planets outside the Solar System. Utilizing a template observing scenario, we quantify SIM sensitivity to single planets orbiting single normal nearby stars as function of measurement errors and properties of the planet: SIM will detect over 95% of the planets with periods between a few days and the 5-year nominal mission lifetime that produce astrometric signatures ～ 2.2 times larger than the single-measurement accuracy. We provide accuracy estimates of full-orbit reconstruction and planet mass determination: at twice the discovery limit, orbital elements will be determined with a typical accuracy of 20- 30%; the astrometric signature must be ～ 10 and ～ 15 times the minimum signal 1University of Pittsburgh, Dept. of Physics Astronomy, Pittsburgh, PA 15260, USA 2Smithsonian Astrophysical Observatory, Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cam- bridge, MA 02138 3Space Telescope Science Institute, Baltimore, MD 21218, USA 4Osservatorio Astronomico di Torino, 10025 Pino Torinese, Italy – 2 – required for detection to derive mass and inclination angle estimates accurate to 10%. We quantify the impact of different observing strategies on th