Astronomers getting better idea of makeup of distant exoplanets

PASADENA, Calif., May 9 (UPI) -- U.S. astronomers say advances in technology, including direct imaging, will give them the ability to probe the makeup of planets outside our solar system.

While ground-based telescopes have begun taking infrared pictures of the planets around distant stars, astronomers say such images will yield even more information if that infrared light can be broken apart into a rainbow of different wavelengths.

As part of Project 1640, partly funded by NASA's Jet Propulsion Laboratory in Pasadena, Calif., researchers are beginning to install infrared cameras on ground-based telescopes equipped with spectrographs, instruments that spread an object's light apart, revealing signatures of molecules.

One such setup has been completed at the Palomar Observatory near San Diego, JPL reported Thursday.

Using it, the researchers examined HR 8799, a large star orbited by at least four known giant red planets.

"In just one hour, we were able to get precise composition information about four planets around one overwhelmingly bright star," JPL's Gautam Vasisht, co-author of a study appearing in the Astrophysical Journal, said. "The star is a hundred thousand times as bright as the planets, so we've developed ways to remove that starlight and isolate the extremely faint light of the planets."

Their study found all four planets, though nearly the same in temperature, have different compositions. Some, unexpectedly, do not have methane in them, and there may be hints of ammonia or other compounds that would also be surprising, they said.