PSJC #21 Oct 6 2008

Kevin Stevenson

Secondary Eclipse Photometry of GJ 436b in Six Spitzer Channels

The nearby exoplanet GJ 436b is a hot Neptune with an equilibrium temperature of approximately 700K, assuming uniform redistribution and 0.3 Bond albedo. This eccentric exoplanet is the only known transiting hot Neptune and the only known transiting M dwarf companion. The Spitzer Exoplanet Target of Opportunity program observes secondary eclipses, where the planet passes behind the star, to provide direct measurements of emitted planetary flux, thus constraining atmospheric models. The observations took place in January and February of 2008 for the 3.6, 4.5, 5.8, 16 and 24-micron events, while GJ 436b was observed at 8.0 microns in June of the previous year. Of the channels that yielded eclipse detections, we will present estimates of infrared brightness temperatures and discuss how they can provide insight into atmospheric composition using current models. Spitzer is operated by the Jet Propulsion Laboratory, California Institute of Technology under a contract with NASA, which provided support for this work.
(link to DPS08 abstract)