Wednesday, February 20, 2013
Hunt for Distant Planets Intensifies
When astronomers discovered planet GJ 1214b circling a star more than 47 light-years from Earth in 2009, their data presented two possibilities. Either it was a mini-Neptune shrouded in a thick atmosphere of hydrogen and helium, or it was a water world nearly three times the size of Earth.
Along came Jacob Bean, now an assistant professor in astronomy & astrophysics at the University of Chicago, who used a new method called multi-object spectroscopy to analyze the planet’s atmosphere from large, ground-based telescopes. Aided by technology, Bean and his colleagues are surmounting the challenge of inferring the atmospheric composition of planets that were invisible to humans just a few years ago.
“We’re trying to distinguish whether it’s like the gas giants we know about, or something fundamentally different from what we’ve seen in our solar system — an atmosphere predominantly composed of water,” Bean said.
The search for exoplanets - planets beyond our own solar system - has taken off over the last decade, and is now a growing component of UChicago’s research agenda in astronomy. One estimate published in January calculated that our Milky Way galaxy alone contains at least 17 billion Earth-sized planets, with a vast potential for life-sustaining worlds. Pursuing the exoplanet search via complementary methods are Bean and Daniel Fabrycky, another assistant professor in astronomy & astrophysics.
Bean has received a 60-orbit allocation on the Hubble Space Telescope to continue his observations on GJ 1214b, a sign of the work’s importance. Previous HST studies of planetary atmospheres encompassed 10 to 20 orbits. Bean will use a technique called transmission spectroscopy to measure the chemical composition of the planet’s atmosphere with unprecedented precision.