About this world
K2-321 b is a sub-Neptune orbiting K2-321, a cool red dwarf 253 light-years from Earth. It is about 2.1 times the size of Earth. It completes an orbit every 2.3 days at 0.028 AU from its star, closer than Mercury is to the Sun, on a strongly elongated orbit (e = 0.44).
Its equilibrium temperature is about 830 K (557 °C): far too hot for liquid water on its surface. By the "cosmic shoreline", its star has probably stripped its atmosphere away, leaving bare rock.
It was discovered in 2020 by transit with K2. A planet crosses its star and dims it by a tiny, periodic fraction.