About this world
HD 39194 d is a sub-Neptune orbiting HD 39194, an orange dwarf (type K0V) 86.1 light-years from Earth. It is about 2.1 times the size of Earth (its size estimated from its mass), with at least 5.2 Earth masses (a minimum, measured by radial velocity). It completes an orbit every 33.9 days at 0.19 AU from its star, closer than Mercury is to the Sun.
Its equilibrium temperature is about 503 K (230 °C): far too hot for liquid water on its surface. By the "cosmic shoreline", it has likely held on to an atmosphere.
It was discovered in 2021 by radial velocity with La Silla Observatory. The star wobbles toward and away from us, Doppler-shifting its spectrum. HD 39194 has 3 known planets; the others are HD 39194 b and HD 39194 c.