Ultra-Hot Jupiter Sets Fire to Everything We Thought We Knew About Exoplanets


Astronomers have discovered that a sweltering exoplanet 650 light years from Earth that carries a lot of game-changing superlatives. KELT-9b, which is three times the mass and twice the diameter of Jupiter, is not only hotter than most stars but contains heavy metals and other atmospheric elements never before seen outside of our solar system.

While KELT-9b was first discovered in 2017, new observations from a team of researchers in Europe reveal that the gas giant has an atmosphere of vaporized iron and titanium, heavy metals that have never been detected in an exoplanet’s atmosphere before. These discoveries were published in the journal Nature on Wednesday.

Artist rendering of KELT-9b and its parent star.


Known as an “ultra hot Jupiter” for being a gas giant like our own solar system’s Jupiter, KELT-9b was already the hottest exoplanet ever recorded, reaching temperatures of up to 7,800 degrees Fahrenheit. While the existence of iron and titanium in an exoplanet’s formation was a previously held theory, neither metal had been detected. But thanks to KELT-9b’s extreme heat, iron and titanium atoms don’t condense into atmospheric clouds, but rather float around as standalone atoms, making them identifiable to scientists.

“As more ultra hot Jupiters continue to be discovered and characterised (by, for example, the TESS space mission), we will obtain a statistical sample of gas-giant exoplanets with a corresponding inventory of metals,” Kevin Heng, an astrophysicist at the University of Bern in Switzerland who participated in the study, said in a blog post. But Heng also warns that given these recent discoveries, scientists need to avoid sticking to theories that may easily be thrown out with the latest surveillance.

“With ultra hot Jupiters, the simplicity of their atmospheric chemistry means there is no place for the theorist to hide her/his free parameters, and theory may be decisively confronted by observations,” Heng explains. His team’s observations show that KELT-9b orbits perpendicular to its star, much like a top that spins closer and closer. While this could mean an inevitable collision, Heng’s team is open to other possibilities.

“It is funny sometimes how science works,” Heng mused. “One can learn a lot by simply assimilating information without having an agenda.” While KELT-9b continues to melt old theories in its fiery equilibrium temperature of 6,830 degrees Fahrenheit, Heng’s team will continue to monitor exoplanets for heavy metals and possible biosignatures that might overturn previously held notions.

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