This exoplanet has metal rain and 2,400C temperatures

Ultra-hot Jupiters — named as such because of their physical similarities to the planet Jupiter — are exoplanets that orbit stars other than the sun with temperatures so high that the molecules in their atmospheres are completely torn apart. They are among the most extreme environments in our galaxy.

They also whip around their parent stars in orbits that only last a few days, and astronomers still aren’t sure how it’s possible for them to form.

While these harsh conditions might sound like they’re as extreme as it gets, astronomers are starting to realize they may just be the tip of the (very hot) iceberg. In a recent study published in The Astrophysical Journal Letters, my colleagues and I discovered that one of these exotic worlds in particular is even more extreme than we’d ever thought.

Ultra-hot worlds

Discovered in 2016, WASP-76b is perhaps the most well-known of these ultra-hot worlds. At double the size of our own planet Jupiter, WASP-76b has day-side temperatures reaching a whopping 2,400 C, and takes less than two days to orbit its parent star. Its claim to fame, however, is a 2020 study suggesting that liquid iron might literally be raining down from its skies.

More recent research, yet to be peer-reviewed, has called this result into question. But there’s no doubt that the conditions on WASP-76b are totally unlike anything here on Earth. WASP-76b can therefore offer us a window into the most extreme physical and chemical processes in our galaxy, and studying its harsh alien conditions can help us place our own solar system into context.

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