Direct detection of water in the thermal emission spectra of hot jupiters

Abstract

Over the past nearly 30 years, over 3500 planets have been discovered orbiting stars other than the Sun. The discovery of these other worlds has revolutionized the field of planetary science from studying the few and distinct planets within the solar system to studying planetary populations in a statistical sense. With this vast new data, we can ask and begin to answer questions about planetary formation and evolution, and what it means for a planet to be habitable. Water is a key component of these answers. Because liq. water is crucial to life on Earth, it has become a std. of whether an exoplanet has the potential to sustain life. Gaseous water in the atmospheres of planets, specifically gas giant planets, can provide a clue to their formation and evolutionary history. Here, we describe a technique that we have pioneered to directly detect the thermal emission from hot Jupiters, gaseous Jupiter-sized planets that orbit their stars in only 3-5 day periods. Historically, hot Jupiters have been assumed to form at large orbital radii, like where our Jupiter exists today, and then migrate in to their current positions. More recent theories have suggested that it may actually be possible for hot Jupiters to have formed in their current orbits. An atm. carbon-to-oxygen (C/O) ratio, obtained from relative measurements of a carbon bearing species, most likely CO or CH_4, and water, could clue us in to where in the protoplanetary disk the planet formed. We will describe how we have used our technique to detect water in hot Jupiter atmospheres and our current approaches to try to simultaneously detect a carbon-bearing species. With these detections made in the same atm., we will be able to constrain the hot Jupiter's C/O ratio and est. where in the disk it formed. Furthermore, our technique promises to be particularly well adaptable for future studies of smaller, terrestrial, habitable zone planets. Water is a key component of planetary atmospheres and our detection of water in hot Jupiters paves the way for future studies of planetary formation and habitability alike.

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