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Follow-Up Study Examines Weather of “Lonely Planet”

Michael Liu

Michael Liu

Beth Biller

Beth Biller

In 2013, a team led by IfA astronomer Michael Liu published a study about a planet called PSO J318.5-22 that did not orbit a star. Now a follow-up study led by Beth Biller, formerly a Hubble Fellow in Liu’s group and now at University of Edinburgh, shows that this planet’s weather includes hot dust and molten rain.

Liu, as well as other researchers based in the US, Germany, France, and Spain, participated in the study. They used a telescope in Chile to study the weather systems in the distant world, which is estimated to be around 20 million years old.

The researchers captured hundreds of infrared images of the object as it rotated over a 5-hour period. By comparing the brightness of PSO J318.5-22 with neighboring bodies, the team discovered that it is covered in multiple layers of thick and thin clouds. These cause changes to the brightness of the distant world as it rotates. The far-off world is around the same size as Jupiter, the largest planet in our solar system, but is roughly eight times more massive. Temperatures inside clouds on PSO J318.5-22 exceed 800° C (about 1,500° F).

The scientists were able to accurately measure changes in brightness on PSO J318.5-22 because it does not orbit a star. Stars like our Sun emit huge amounts of light, which can complicate measurements made of the brightness of objects orbiting them. The team hopes to adapt the technique so they can study planets that do orbit stars. Such techniques may eventually be applicable to cooler, lower mass planets, which are more likely to be capable of supporting life.

the lonely planet

Pan-STARRS1 telescope multicolor image of the free-floating planet PSO J318.5-2, in the constellation of Capricornus. Credit: N. Metcalfe & Pan-STARRS 1 Science Consortium.

Findings from the study could improve scientists’ ability to find out if conditions in far-off planets are capable of sustaining life. Said Biller, “This discovery shows just how ubiquitous clouds are in planets and planet-like objects. We’re working on extending this technique to giant planets around young stars, and eventually we hope to detect weather in Earth-like exoplanets that may harbor life.”