About this world
TOI-2458 c is a sub-Neptune orbiting TOI-2458, a yellow-white F-type star (type F9-F9.5) 368 light-years from Earth. It is about 3.2 times the size of Earth (its size estimated from its mass), with at least 10 Earth masses (a minimum, measured by radial velocity). It completes an orbit every 16.6 days at 0.13 AU from its star, closer than Mercury is to the Sun, on a strongly elongated orbit (e = 0.29).
Its equilibrium temperature is about 923 K (650 °C): far too hot for liquid water on its surface. At its size it almost certainly keeps a deep envelope of hydrogen and helium.
It was discovered in 2024 by radial velocity with La Silla Observatory. The star wobbles toward and away from us, Doppler-shifting its spectrum. TOI-2458 has 2 known planets; the others are TOI-2458 b.