K2-141 b

K2-141b (also designated EPIC 246393474.01) is a massive rocky exoplanet orbiting extremely close to a K Type orange main-sequence star K2-141. The planet was first discovered by the Kepler space telescope during its K2 “Second Light” mission and later observed by the HARPS-N spectrograph. It is classified as an ultra-short period planet (USP) and is confirmed to be terrestrial in nature. Its high density implies a massive iron core taking up between 30% and 50% of the planet's total mass.

==Characteristics== ===Mass and radius=== Like the majority of known exoplanets, K2-141b was detected using the transit method, where a planet blocks a tiny fraction of its star's light as it passed between our line of the sight and its host. This method is only able to determine the radius of the planet, not its mass. However, K2-141b was also detected by the radial velocity method using the HARPS-N spectrograph. Therefore, its mass could also be determined along with its radius. The planet is classified as a Super-Earth, being significantly larger and more massive than Earth but not as large as the ice giants Uranus and Neptune. K2-141b has a radius of 1.51 , below the 1.6 threshold where most planets are expected to accumulate thick hydrogen and helium atmospheres, transforming them into mini-Neptunes. The planet's mass confirms that it is rocky. It has a mass of 5.08 , which gives K2-141b a high density of 8.2 g/cm3, about 1.48 times the density of Earth. This high density implies a composition with a large iron core taking up about 30% to 50% of the planet's total mass.