Bizarre super-puffy exoplanet hosts rare 'thermometer molecule'

By Robert Lea published 43 minutes ago

The molecule chromium hydride is usually found in stars but was discovered in the atmosphere of the hot Jupiter WASP-31b, which is one of the lightest exoplanets ever seen.



An illustration of an orange jupiter-like planet with a bright yellow-white star in the distance
An illustration shows a hot Jupiter exoplanet orbiting close to its parent star. (Image credit: NASA, ESA, and J. Olmsted (STScI))


Astronomers have discovered a rare temperature-sensitive molecule that is usually associated with stars in the atmosphere of an exoplanet for the first time.

The "thermometer molecule" chromium hydride is abundant in a narrow range of temperatures between 1,700 degrees Fahrenheit to 3,140 degrees Fahrenheit (926 to 1,730 degrees Celsius). It was discovered in the atmosphere of the "hot Jupiter" exoplanet WASP-17b, which orbits an F-type star located around 1,250 light-years from Earth.

The discovery of such a metal hydride — a metal bonded to hydrogen to form a new compound — in the atmosphere of an alien planet could allow scientists to gauge the temperatures of worlds outside the solar system in a new way.

"Chromium hydride molecules are very temperature sensitive," research lead author Laura Flagg, a research associate at Cornell University in New York, said in a statement. "At hotter temperatures, you see just chromium alone. And at lower temperatures, it turns into other things. So there’s only a specific temperature range where chromium hydride is seen in large abundances."

More:
https://www.space.com/hot-jupiter-exoplanet-thermometer-molecule