Astronomers have discovered an extraordinary Super-Earth, K2-360 b, boasting a density comparable to lead. This rocky exoplanet, located light-years away, is a cosmic anomaly—packing 7.7 times Earth’s mass into a size just 1.6 times larger than our planet. Its density, measured at 11 grams per cubic centimeter, surpasses almost every known exoplanet in its class.
K2-360 b falls into the ultra-short-period (USP) Super-Earth category, with an orbital “year” lasting just 21 Earth hours. This extreme proximity to its host star not only makes it easier to observe but also sheds light on its unique formation and composition.
Discovered in 2016 through NASA’s K2 mission, the planet’s shadow was initially detected as it passed in front of its star. Recent follow-up studies allowed astronomers to measure its mass and radius, leading to its astonishing density calculations.
The Making of a Dense World
K2-360 b’s incredible density likely stems from its interior structure. Models suggest the planet is dominated by a massive iron core, comprising approximately 48% of its mass. Researchers hypothesize that K2-360 b might be the stripped core of a former gas giant. Over time, the planet likely migrated closer to its host star, where intense radiation stripped away its gaseous envelope, leaving behind a rocky, lava-covered remnant.
K2-360 b shares its system with a larger companion, K2-360 c, resembling Neptune in size and density. The gravitational interaction between the two planets may have driven K2-360 b into its close orbit through a process known as high-eccentricity migration, where an initially elongated orbit was gradually circularized due to tidal forces.
A Universe of Curiosities
K2-360 b joins the ranks of some of the densest exoplanets ever discovered, standing out even among other extreme worlds like TOI-1853b. Its discovery not only expands the catalog of exotic planets but also offers insights into planetary evolution under intense stellar conditions.
The findings, published in Scientific Reports, highlight the staggering variety of planetary systems across the cosmos, many of which rival the imagination of science fiction.
