About this world
BD+05 4868 A b is a sub-Neptune orbiting BD+05 4868 A, an orange dwarf (type KV) 142 light-years from Earth. It is about 2.4 times the size of Earth (its size estimated from its mass) and holds 6.2 Earth masses. It completes an orbit every 1.27 days at 0.021 AU from its star, closer than Mercury is to the Sun.
Its equilibrium temperature is about 1,820 K (1,547 °C): far too hot for liquid water on its surface. At its size it almost certainly keeps a deep envelope of hydrogen and helium. Its atmosphere has already been studied in one spectroscopic observation by the James Webb Space Telescope.
It was discovered in 2025 by transit with Transiting Exoplanet Survey Satellite (TESS). A planet crosses its star and dims it by a tiny, periodic fraction.