Discovery and Characterization of Transiting Super Earths Using an All-Sky Transit Survey and Follow-up by the<i>James Webb Space Telescope</i>

Abstract

Doppler and transit surveys are finding extrasolar planets of ever smaller\nmass and radius, and are now sampling the domain of superEarths (1-3 Earth\nradii). Recent results from the Doppler surveys suggest that discovery of a\ntransiting superEarth in the habitable zone of a lower main sequence star may\nbe possible. We evaluate the prospects for an all-sky transit survey targeted\nto the brightest stars, that would find the most favorable cases for\nphotometric and spectroscopic characterization using the James Webb Space\nTelescope (JWST). We use the proposed Transiting Exoplanet Survey Satellite\n(TESS) as representative of an all-sky survey. We couple the simulated TESS\nyield to a sensitivity model for the MIRI and NIRSpec instruments on JWST. We\nfocus on the TESS planets with radii between Earth and Neptune. Our simulations\nconsider secondary eclipse filter photometry using JWST/MIRI, comparing the 11-\nand 15-micron bands to measure CO2 absorption in superEarths, as well as\nJWST/NIRSpec spectroscopy of water absorption from 1.7-3.0 microns, and CO2\nabsorption at 4.3-microns. We project that TESS will discover about eight\nnearby habitable transiting superEarths. The principal sources of uncertainty\nin the prospects for JWST characterization of habitable superEarths are\nsuperEarth frequency and the nature of superEarth atmospheres. Based on our\nestimates of these uncertainties, we project that JWST will be able to measure\nthe temperature, and identify molecular absorptions (water, CO2) in one to four\nnearby habitable TESS superEarths.\n