Astronomers say they’ve confirmed the presence of water vapor and carbon monoxide in the atmosphere of a giant planet beyond our solar system, thanks to the most detailed spectroscopic scan ever made.
The observations, detailed Thursday on the journal Science’s website, uses a method that could someday be used to sample the air of an alien Earth from light-years away, the researchers said.
Image: An artist’s rendering shows the HR 8799 planetary system at an early stage in its evolution, with HR 8799c in the foreground. That giant planet orbits its parent star at a distance comparable to Pluto’s distance from our sun. Credit: Dunlap Institute for Astronomy and Astrophysics; Mediafarm
“The big surprise was actually that we could do it,” one of the study’s co-authors, Travis Barman of the Lowell Observatory in Arizona, told reporters. “We can actually see the individual lines of these molecules. … I personally felt like we would not be able to do what we have done.”
This isn’t the first time scientists have studied the atmosphere of HR 8799c, a planet about seven times as massive as Jupiter that orbits a star 130 light-years from Earth. The HR 8799 system is special because astronomers can actually pick up the light of several giant planets that orbit outside the glare of their parent star. HR 8799c, for example, follows an orbit similar to the one Pluto traces around our own sun.
That’s what makes it possible for astronomers to get the “chemical fingerprint” of the planet’s atmosphere. One team did it three years ago with an instrument on the European Southern Observatory’s Very Large Telescope in Chile. Another team reported just this week that they did it for four planets in the HR 8799 system using an instrument known as Project 1640 on the Palomar Observatory’s Hale Telescope in California.