UW Today

May 17, 2017

Visiting astronomer at UW part of ‘Styrofoam’ planet discovery

News and Information

David James, a visiting scientist with the University of Washington Department of Astronomy, assisted in the just-announced Lehigh University-led discovery of an exoplanet 320 light-years away with a density so light it is being called a “Styrofoam planet.”

This “puffy planet,” as it is also called, is KELT-11b, an extreme version of a gas giant like Jupiter or Saturn but which orbits so close to its host star it completes an orbit in five days.

“It is highly inflated, so that while it’s only a fifth as massive as Jupiter, it is nearly 40 percent larger, making it about as dense as Styrofoam,” said Joshua Pepper, assistant professor of physics at Lehigh. The research team’s paper was published this month in the Astronomical Journal.

An artist's rendering of KELT-11b, a "Styrofoam"-density exoplanet orbiting a bright star in the southern hemisphere.

An artist’s rendering of KELT-11b, a “Styrofoam”-density exoplanet orbiting a bright star in the southern hemisphere.Walter Robinson/Lehigh University

The host star, KELT-11, is named for the telescope used to discover it, KELT, the Kilodegree Extremely Little Telescope, which uses two small robotic telescopes, one in Arizona and the other in South Africa. James helped Pepper build and install the South Africa telescope, which he also helps operate. The telescope detects exoplanets by the dimming of light when the planets transit, or pass in front of, their host star.

“Because the new exoplanet’s host star is extremely bright, we can perform precise observations of its atmospheric properties, directly comparing its fundamental physical nature to that of Jupiter and Saturn, making it a prime benchmark for measuring the atmospheres of other planets,” James said.

Such observations help astronomers develop tools to see the types of gases in atmospheres, which will be necessary in the next 10 years when they apply similar techniques to Earth-like exoplanets with next-generation telescopes now under construction.

Planets discovered by the KELT survey will be observed in detail by large space telescopes such as Hubble and Spitzer and the James Webb Space Telescope, scheduled to launch in 2018.

James is among more than 30 contributors to the research. Coauthors include researchers at NASA, Harvard University, the University of Pennsylvania and the University of California, Berkeley, among others in the United States and abroad. About 40 “citizen scientists” in 10 countries across four continents also contributed to the project and several contributed directly to the discovery of KELT-11b and are co-authors on the paper.

The discovery caused Pepper and coauthors to muse that school children who for generations have created Styrofoam models of the solar system “may have had the right idea.”


This is based on a release from Lehigh University and comments from James. Read more about the discovery here. For more information about his work, contact him at 914-320-0084 or djames44@gmail.com.