Expected Planet and False Positive Detection Rates for the Transiting Exoplanet Survey Satellite

The proposed Transiting Exoplanet Survey Satellite (TESS) will survey the entire sky to locate the nearest and brightest transiting extrasolar planets with orbital periods up to about 36 days. Here we estimate the number and kind of astrophysical false positives that TESS will report, along with the number of extrasolar planets. These estimates are then used to size the groundbased follow-up observing efforts needed to confirm and characterize the planets. We estimate that the needed observing resources will be about 1400 telescope-nights of imaging with 0.5m to 1m-class telescopes, 300 telescope-nights with 1m to 2m-class telescopes for the classification of the host stars and for radial velocity measurements with roughly 1 km s precision, and 380 telescope-nights with 2m to 4m-class telescopes for radial velocity studies with precision of a few m s. Follow-up spectroscopy of the smallest planets discovered by TESS at the best possible velocity precision will be limited by the number of telescope nights available on 4m to 10-m class telescopes with instruments such as HARPS and HIRES, but the pay-off of such efforts will be the determination of masses for Super Earths with sufficient accuracy to distinguish rocky desert planets from water worlds. Subject headings: extrasolar planets, astronomical techniques 1. History and Motivation Photometric surveys to detect transits by extrasolar planets have recently become a productive means of locating these objects (e.g., Koch et al. 1998; Alonso et al. 2004; Bakos et al. 2004; Baglin et al. 2007; Walker et al. 2003). All such surveys must deal with astrophysical false positives, i.e., periodic transit-like decreases in stellar brightness that arise from stars orbited by other stars, as opposed to stars orbited by planets. In most surveys these false positives outnumber those from planetary transits, often by factors of ten or more. The proposed Transiting Exoplanet Survey Satellite (TESS) seeks to use an orbiting array of 6 small-aperture, wide-field CCD cameras (190 mm focal length f/1.5, with 18-degree square field of view) to survey the entire sky in a 2-year observing campaign, yielding a comprehensive list of transiting planets orbiting 2.5 million of the nearest stars. From a near-equatorial orbit, TESS will be able to observe the whole sky, and to detect objects with transit depths as small as 3×10 of the brightness of the parent star, with periods up to 36 days. These sensitivities will allow detection of Neptune-sized planets transiting Sun-like stars, and Super Earths around stars with radii some-