Exoplanet GJ 523b discovered with 23 times Earth's mass

Astronomers have discovered an unusual exoplanet, GJ 523b, which possesses a mass approximately 23.5 times that of Earth. Despite its significant size, the planet appears to be primarily rocky rather than a gas giant, challenging existing models of planetary formation.

Initially identified by NASA’s TESS satellite, the planet is roughly 2.55 times wider than Earth. High density suggests it has a relatively thin atmosphere. Follow-up measurements were conducted by researchers from the University of Wisconsin-Madison using the WIYN 3.5-meter telescope at the Kitt Peak National Observatory in Arizona.

GJ 523b orbits its star every 17.75 days within a planetary system estimated to be 170 million years old. While planets of this mass in our solar system, such as Jupiter, typically accumulate thick layers of hydrogen and helium, GJ 523b remains a “mega-Earth.” Scientists hypothesize that the planet may have lost its original thick atmosphere due to stellar radiation or a massive collision between two planets.