About this world
TOI-799 b is a sub-Neptune orbiting TOI-799, a yellow, Sun-like star 517 light-years from Earth. It is about 2.1 times the size of Earth. It completes an orbit every 5.55 days at 0.061 AU from its star, closer than Mercury is to the Sun.
Its equilibrium temperature is about 959 K (686 °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 2026 by transit with Transiting Exoplanet Survey Satellite (TESS). A planet crosses its star and dims it by a tiny, periodic fraction.