A huge, unusually dense planet more than twice the size of Earth is puzzling scientists because it has very little atmosphere, despite being massive enough that researchers would expect it to have accumulated a thick layer of gas. The planet, named GJ 523b, is around 170 million years old and more than 2.5 times the size of Earth. It has approximately 23 times Earth’s weight and is about 60 percent the size of Neptune, according to researchers at the University of Wisconsin-Madison.
A release from the university described it as mostly dense rock surrounding a massive core. This planet is two and a half times bigger than the Earth.” A Mega-Earth is an exceptionally large and dense terrestrial planet outside our solar system. It is more massive than a typical “super-Earth” and is thought to consist largely of solid material such as rock and metal.
Beatty said GJ 523b could help scientists define the category more clearly. Researchers need geologists who can understand how iron and rock behave under pressures that cannot be reproduced in laboratories on Earth, as well as atmospheric scientists who can help determine how much of the planet is actually rock, Beatty said. GJ 523b was first identified as a candidate by NASA’s Transiting Exoplanet Survey Satellite, or TESS.
The satellite searches for planets by monitoring stars for regular dips in brightness, which may happen when an orbiting planet crosses in front of its star. It’s blocking some of the light from the star, and the star gets dimmer.” Kroft followed up on the candidate using the WIYN telescope in Arizona. The team also used data collected by the James Webb Space Telescope to investigate the planet’s density and atmosphere.
The release noted that scientists generally expect a growing core of rock and metal to pull in a hydrogen-rich atmosphere. In our solar system, planets such as Jupiter and Saturn developed massive atmospheres after reaching around 20 times Earth’s mass. The researchers have proposed several possible explanations, the university said.
GJ 523b may once have orbited so close to its star that extreme heat stripped away much of its atmosphere. Alternatively, it could have formed when two planets collided, with the impact heat stripping away the atmosphere. Contact Newsweek editors on this story: Matthew Robinson and Sam Wilson.
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