About this world
YZ Cet b is an Earth-sized planet orbiting YZ Cet, a cool red dwarf (type M4.5V) 12.1 light-years from Earth. It is about 0.91 times the size of Earth (its size estimated from its mass), with at least 0.7 Earth masses (a minimum, measured by radial velocity). It completes an orbit every 2.02 days at 0.016 AU from its star, closer than Mercury is to the Sun.
Its equilibrium temperature is about 471 K (198 °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 2017 by radial velocity with La Silla Observatory. The star wobbles toward and away from us, Doppler-shifting its spectrum. YZ Cet has 3 known planets; the others are YZ Cet c and YZ Cet d.