A scorching-hot exoplanet has such extreme conditions that molten iron rains down from the sky. WASP-76 b is an “ultrahot Jupiter” that’s located in the constellation Pisces approximately 640 light-year away from us. Discovered in 2013, WASP-76 b is about as large as Jupiter but almost twice as wide.
The exoplanet is in such a tight orbit with its host star (WASP-76) that it completes its orbit in just 1.8 Earth days which is an incredibly short amount of time as it takes Mercury (the closest planet to our sun) 88 days to complete an orbit. Additionally, WASP-76 b is “tidally locked” to its host star which means that only one side of the exoplanet is facing the star at all times.
The side that continuously faces the star (called the dayside) has extreme temperatures that are high enough to vaporize metals at 4,350 degrees Fahrenheit (2,400 degrees Celsius). The nightside of the planet is a bit cooler, but still exceptionally hot, at 2,730 degrees Fahrenheit (1,500 degrees Celsius).
David Ehrenreich, who is an associate professor of astronomy at the University of Geneva in Switzerland as well as the lead author of the study (which can be read here), told Space.com, “These are likely the most extreme climates we could ever find on a planet.”
The researchers used the Echelle Spectrograph for Rocky Exoplanets and Stable Spectroscopic Observations (or ESPRESSO) to study WASP-76 b and noticed that there was a large amount of iron vapor located at the “evening” border which separates the exoplanet’s dayside from the nightside. On the other hand, there were no signs of iron at the “morning” border which is located on the opposite side of the planet.
“Something must be happening on the nightside that makes iron disappear,” Ehrenreich stated. The most logical explanation is that the strong winds carry the vaporized iron from the dayside to the nightside where it condenses into clouds full of iron droplets and begins raining iron. “One could say that this planet gets rainy in the evening – except it rains iron,” he said, adding that the winds blow at an exceptionally high speed of approximately 11,000 mph.
Ehrenreich finished off by saying, “Exoplanets are a real treasure trove full of surprises,” adding, “The more you look, the more you find.” “What we have now is a whole new way to trace the climate of the most extreme exoplanets.” And WASP-76 b is certainly an extreme exoplanet as it’s hot enough to vaporize metal. Now that’s hot!