A huge, dense planet, more than twice Earth’s size, is intriguing scientists due to its minimal atmosphere. Named GJ 523b, this planet should theoretically have amassed a thick gas layer given its mass. The University of Wisconsin-Madison’s research highlights its unusual properties.
Planetary Characteristics
GJ 523b is approximately 170 million years old, measuring over 2.5 times Earth’s size. It has a mass 23 times that of Earth, roughly 60% of Neptune’s size. Researchers from the university describe it as primarily dense rock surrounding a vast core. Max Kroft, a lead researcher, remarked on the surprising nature of such a large, dense planet having minimal atmosphere.
Understanding Mega-Earths
A Mega-Earth is a large, dense planet located outside our solar system, comprised mostly of solid rock and metal. The planet GJ 523b offers a clearer definition of this category. According to Professor Thomas Beatty, this discovery assists in defining what qualifies as a Mega-Earth.
Beatty emphasized the need for interdisciplinary expertise. Geologists are crucial to comprehend rock and iron behavior under extraterrestrial pressures, while atmospheric scientists help determine its composition. NASA’s Transiting Exoplanet Survey Satellite (TESS) first identified GJ 523b through observed dips in a star’s brightness, hinting at an orbiting planet.
Investigation Techniques
Researchers observed periodic dimming in the star’s light, suggesting a planetary transit. Max Kroft used the WIYN telescope in Arizona to study the candidate further. Additional data from the James Webb Space Telescope helped analyze the planet’s atmosphere and density.
Reasons for Minimal Atmosphere
Typically, planets with a rocky core attract a hydrogen-rich atmosphere once reaching 20 times Earth’s mass. Planets like Jupiter and Saturn followed this developmental path. However, GJ 523b’s small atmosphere puzzled scientists.
Possible reasons include proximity to its star, where heat stripped the atmosphere away, or a past collision with another planet generating heat that dispersed the atmosphere. Kroft explains that extreme heat prevents atmosphere retention, leading to a rocky body without much atmospheric cover.