My Research: Heather A. Knutson

My Research:

First longitudinal temperature profile for an extrasolar planet.  This image shows the day-night temperature profile on the hot Jupiter HD 189733b (Image credit: H. Knutson, NASA/JPL-Caltech).

 "I am interested in characterizing the atmospheres of planets orbiting nearby stars, including their temperatures, compositions, and atmospheric circulation patterns.  The planets I study are too far and too faint to resolve directly, therefore I use observations of eclipsing systems, where the planet periodically passes in front of and then behind its parent star, to infer their properties.

Many of these unique worlds have characteristics that differ substantially from those of the solar system planets.  For example, there is an entire class of hot, Jupiter-like planets that orbit at a fraction of the earth-sun distance.  Observations of these systems allow us to study the potential diversity of planetary atmospheres and provide an important testing ground for our models of these atmospheres."

WHAT IS A HOT JUPITER?

“Hot Jupiters” are a class of massive, gas-giant planets with primarily hydrogen/helium compositions similar to that of Jupiter.  Unlike Jupiter, they orbit extremely close to their parent stars and have temperatures between 1000-2500 K.  As a result of their short orbital periods we expect that these planets should be tidally locked (meaning that just like the earth-moon system, the same side of the planet always faces the star).  In 2007 I measured the day-night temperature gradient for the hot Jupiter HD 189733b and found that the day side is a scorching 1200 K while the night side is a relatively balmy 1000 K.  The image on top shows the resulting brightness temperature map for the planet; the hottest region on the planet is located 30 degrees east of the substellar point.  The image on bottom is an artist’s impression of what a hot Jupiter might look like (Image credit ESA/C. Carreau).

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