Planets orbiting red dwarf stars, often with short orbital periods.Red dwarf stars are the most common stars in the galaxy, and their planets are prime targets for exoplanet searches. These planets often orbit very close to their dim, cool parent stars, resulting in short orbital periods of days or even hours. Because the habitable zone around a red dwarf is so close, planets there are frequently tidally locked, with one hemisphere permanently facing the star and the other in eternal darkness. This creates extreme temperature contrasts and unique atmospheric circulation patterns.
The first confirmed exoplanet around a red dwarf, Gliese 876 b, was discovered in 1998 by a team led by Geoffrey Marcy and Paul Butler. Since then, surveys like MEarth and TRAPPIST have revealed many more, including the famous TRAPPIST-1 system with seven Earth-sized planets.
Red dwarfs are small and faint, so their gravitational pull is weaker than that of Sun-like stars, allowing planets to orbit very close without being destroyed. The close orbit means the planet's year is short, and tidal forces from the star can cause significant internal heating, a process called tidal dissipation. This heating can melt planetary interiors, drive volcanic activity, and even sustain subsurface oceans, as seen in some of the most intriguing exoplanet models.
Red dwarf planets are the primary targets for upcoming missions like the James Webb Space Telescope, which will analyze their atmospheres for biosignatures, and they are also studied to understand tidal heating and orbital dynamics in extreme environments.
Because red dwarfs are so dim, a planet in their habitable zone would have its star appearing as a large, glowing red disk in the sky, and the planet would be in perpetual twilight on its day side.


























