About this world
HD 115404 A b is a Neptune-like planet orbiting HD 115404 A, an orange dwarf (type K2V) 35.8 light-years from Earth. It is about 0.54 times the size of Jupiter (its size estimated from its mass), with at least 0.097 Jupiter masses (a minimum, measured by radial velocity). It completes an orbit every 10.5 days at 0.088 AU from its star, closer than Mercury is to the Sun, on a strongly elongated orbit (e = 0.23).
Its equilibrium temperature is about 696 K (423 °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 2022 by radial velocity with Multiple Observatories. The star wobbles toward and away from us, Doppler-shifting its spectrum. HD 115404 A has 2 known planets; the others are HD 115404 A c.