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Astrophysics Luncheon Seminar

Transmission Spectroscopy for Comparative Planetology
Presented by Jonathan Fraine
California Institute of Technology / University of Maryland / Pontificia Universidad Católica de Chile

Monday, February 2, 2015
12:00 noon in 169-336

Abstract
We used the Kepler, Hubble, and Spitzer Space Telescopes to probe the diversity of exoplanetary atmospheres with transmission spectroscopy, constraining atomic and molecular absorption in Jupiter- and Neptune-sized exoplanets. The detections and non-detections of molecular species such as water, methane, and carbon monoxide lead to greater understanding of planet formation and evolution. Recent significant advances in both theoretical and observational discoveries from planets like HD189733b, HD209458b, GJ436, as well as our own work with HAT-P-11b and GJ1214b, have shown that the range of measurable atmospheric properties spans from clear, molecular absorption dominated worlds to opaque worlds, with cloudy, hazy, or high mean molecular weight atmospheres. Characterization of these significant non-detections allows us to infer the existence of cloud compositions at high altitudes, or mean molecular weights upwards of ~1000x solar. Neither scenario was expected from extrapolations of solar system analogs. I will present our published results from GJ1214b and HAT-P-11b, as well as our recent work using Spitzer. Transmission spectroscopy reveals evidence of atmospheric hazes and clouds, and places constraints on the relative abundance of water vapor, methane, and carbon monoxide-- in the case of cloud-free atmospheres. I will discuss how our results compare to transmission spectra obtained for other similar planets, and use these combined data to develop a better understanding for the nature of these distant and alien worlds.

JPL Contact: Neal Turner (3-0049)


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