About this world
TOI-1728 b is a Neptune-like planet orbiting TOI-1728, a cool red dwarf (type M0) 198 light-years from Earth. It is about 5 times the size of Earth and holds 27 Earth masses. It completes an orbit every 3.49 days at 0.039 AU from its star, closer than Mercury is to the Sun.
Its equilibrium temperature is about 767 K (494 °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 2020 by transit with Transiting Exoplanet Survey Satellite (TESS). A planet crosses its star and dims it by a tiny, periodic fraction.