2015 AAAS Annual Meeting (12-16 February 2015)

February 12 - 16, 2015

Exoplanets: New Worlds Aplenty

Discoveries of thousands of planets orbiting other stars (exoplanets) have excited the science community and the public by determining that most stars have planets and that exoplanets similar in size to the Earth are common. This session provides recent results for planets orbiting both single stars and binary systems. The combination of Doppler velocity measurements and transit photometry and variations of transit timing allow the deduction of whether the planet is rocky, an ice/water planet, or mostly gas. The condition for a planet to be considered in the habitable zone seems simple: the planet must have a stellar flux level consistent with the possibility of having liquid water on its surface. However, determination of whether this condition is fulfilled depends not only on estimates of the distance of the planet from its host star and the size, temperature, and spectra of the star, but also on model assumptions for the atmosphere and cloud properties. Results from one-dimensional and three-dimensional models are discussed. An important result of exoplanet surveys will be the determination of the frequency of Earth-size planets (eta-Earth) in the habitable zone of solar-like stars. However, observations provide a very biased sample. Current work is presented showing our progress toward accurate and reliable estimates of eta-Earth. Capabilities of missions under development that can find the nearest planets and characterize their atmospheres are also discussed.