Astronomers Find a “Thermometer Molecule” that Only Appears When a Planet is Between 1,200 and 2,000 Kelvin

A recent study published in The Astrophysical Journal Letters examines a rare alloy molecule known as chromium hydride (CrH) and its first-time confirmation on exoplanet, WASP-31 b. Traditionally, CrH is only found in large quantities between 1,200 to 2,000 degrees Kelvin (926.85 to 1,726.85 degrees Celsius/1700 to 3,140 degrees Fahrenheit). Therefore, astronomers like Dr. Laura Flagg in the Department of Astronomy and Carl Sagan Institute at Cornell University refer to CrH as a “thermometer for stars”, as CrH is traditionally used to ascertain the temperature of cool stars and brown dwarfs.

For the study, the researchers analyzed the transmission spectrum of WASP-31 b using a combination of data from March 2022 and archival data from 2017 to ascertain that WASP-31 b possessed CrH within its atmosphere. The reason why the 2017 data was included in this current study was because it was initially not used to identify metal hydrides.

While the research team states this is the first confirmed detection of CrH on an exoplanet, this research builds on a 2021 study which reported the first evidence for CrH in the atmosphere of WASP-31 b, but those researchers stopped short of calling it a confirmed finding based on their data at the time.

With this new confirmation of CrH, the team notes this could open doors for using high-resolution observations for studying exoplanet atmospheres, going as far as saying WASP-31 b will not be the last exoplanet where the presence of CrH will be confirmed.

How many more exoplanets will astronomers confirm the presence of CrH throughout the cosmos, and what can CrH teach us about exoplanet atmospheres in the coming years and decades? Only time will tell, and this is why we science!

As always, keep doing science & keep looking up!

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