Discovered by: Luca Malavolta et al. and Barragán et al. using NASA's Kepler telescope
Date: January 18, 2018
Key Facts: This discovery includes a super Earth five times Earth's mass, that orbits an orange Sun-like star. This planet takes only six hours to orbit its K-type star, a journey that takes Mercury 88 days, making it a hot inferno world! K2-141 b is denser than Earth because of its greater mass and its larger iron core. It also has a Neptune-size companion that takes about eight days to orbit the same star.
What's new: The super Earth K2-141 b is what's known as an ultra-short period planet, a class of planet that takes less than one day to orbit its star. The origin of these planets is still a mystery. Similar short-orbit rocky planets might be lava-ocean worlds, because of their scorching heat from their nearby star. The discovery of the rocky K2-141 b may help explain how these planets form.
See details and check the official NASA planet count at the NASA Exoplanet Archive
Paper: "An ultra-short period rocky super-Earth with a secondary eclipse and a Neptune-like companion around K2-141"