About this world
TOI-1203 c is a sub-Neptune orbiting TOI-1203, a yellow, Sun-like star (type G3V) 212 light-years from Earth. It is about 2.2 times the size of Earth (its size estimated from its mass), with at least 5.5 Earth masses (a minimum, measured by radial velocity). It completes an orbit every 13.1 days at 0.1 AU from its star, closer than Mercury is to the Sun.
Its equilibrium temperature is about 929 K (656 °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 2025 by radial velocity with La Silla Observatory. The star wobbles toward and away from us, Doppler-shifting its spectrum. TOI-1203 has 4 known planets; the others are TOI-1203 b, TOI-1203.01 and TOI-1203 e.