Red dwarf in the context of "Extrasolar planet"

An exoplanet or extrasolar planet is a planet outside of the Solar System. The first confirmed detection of an exoplanet was in 1992 around a pulsar, and the first detection around a main-sequence star was in 1995. A different planet, first detected in 1988, was confirmed in 2003. In 2016, it was recognized that the first possible evidence of an exoplanet had been noted in 1917. As of 30 October 2025, there are 6,042 confirmed exoplanets in 4,501 planetary systems, with 1,020 systems having more than one planet.

There are many methods of detecting exoplanets. Transit photometry and Doppler spectroscopy have found the most, but these methods suffer from a clear observational bias favoring the detection of planets near the star; thus, 85% of the exoplanets detected are inside the tidal locking zone. About 1 in 5 Sun-like stars are estimated to have an "Earth-sized" planet in the habitable zone. Assuming there are 200 billion stars in the Milky Way, it can be hypothesized that there are 11 billion potentially habitable Earth-sized planets in the Milky Way, rising to 40 billion if planets orbiting the numerous red dwarfs are included.

Stellar evolution is the process by which a star changes over the course of time. Depending on the mass of the star, its lifetime can range from a few million years for the most massive to trillions of years for the least massive, which is considerably longer than the current age of the universe. The table shows the lifetimes of stars as a function of their masses. All stars are formed from collapsing clouds of gas and dust, often called nebulae or molecular clouds. Over the course of millions of years, these protostars settle down into a state of equilibrium, becoming what is known as a main sequence star.

Nuclear fusion powers a star for most of its existence. Initially the energy is generated by the fusion of hydrogen atoms at the core of the main-sequence star. Later, as the preponderance of atoms at the core becomes helium, stars like the Sun begin to fuse hydrogen along a spherical shell surrounding the core. This process causes the star to gradually grow in size, passing through the subgiant stage until it reaches the red-giant phase. Stars with at least half the mass of the Sun can also begin to generate energy through the fusion of helium at their core, whereas more-massive stars can fuse heavier elements along a series of concentric shells. Once a star like the Sun has exhausted its nuclear fuel, its core collapses into a dense white dwarf and the outer layers are expelled as a planetary nebula. Stars with around ten or more times the mass of the Sun can explode in a supernova as their inert iron cores collapse into an extremely dense neutron star or black hole. Although the universe is not old enough for any of the smallest red dwarfs to have reached the end of their existence, stellar models suggest they will slowly become brighter and hotter before running out of hydrogen fuel and becoming low-mass white dwarfs.

This list covers all known stars, white dwarfs, brown dwarfs, and sub-brown dwarfs/rogue planets within 20 light-years (6.13 parsecs) of the Sun. So far, 131 such objects have been found. Only 22 are bright enough to be visible without a telescope, for which the star's visible light needs to reach or exceed the dimmest brightness visible to the naked eye from Earth, which is typically around 6.5 apparent magnitude.

The known 131 objects are bound in 94 stellar systems. Of those, 103 are main sequence stars: 80 red dwarfs and 23 "typical" stars having greater mass. Additionally, astronomers have found 6 white dwarfs (stars that have exhausted all fusible hydrogen), 21 brown dwarfs, as well as 1 sub-brown dwarf, WISE 0855−0714 (possibly a rogue planet). The closest system is Alpha Centauri, with Proxima Centauri as the closest star in that system, at 4.2465 light-years from Earth. The brightest, most massive and most luminous object among those 131 is Sirius A, which is also the brightest star in Earth's night sky; its white dwarf companion Sirius B is the hottest object among them. The largest object within the 20 light-years is Procyon.

An exoplanet or extrasolar planet is a planet outside of the Solar System. The first confirmed detection of an exoplanet was in 1992 around a pulsar, and the first detection around a main-sequence star was in 1995. A different planet, first detected in 1988, was confirmed in 2003. In 2016, it was recognized that the first possible evidence of an exoplanet had been noted in 1917. As of 4 December 2025, there are 6,053 confirmed exoplanets in 4,510 planetary systems, with 1,022 systems having more than one planet.

There are many methods of detecting exoplanets. Transit photometry and Doppler spectroscopy have found the most, but these methods suffer from a clear observational bias favoring the detection of planets near the star; thus, 85% of the exoplanets detected are inside the tidal locking zone. About 1 in 5 Sun-like stars are estimated to have an "Earth-sized" planet in the habitable zone. Assuming there are 200 billion stars in the Milky Way, it can be hypothesized that there are 11 billion potentially habitable Earth-sized planets in the Milky Way, rising to 40 billion if planets orbiting the numerous red dwarfs are included.

Proxima Centauri, the nearest star to Earth after the Sun, is located 4.25 light-years (1.3 parsecs) away in the southern constellation of Centaurus. Discovered in 1915 by Robert Innes, it is a small, low-mass star, too faint to be seen with the naked eye, with an apparent magnitude of 11.13. Proxima Centauri is a member of the Alpha Centauri star system, being identified as component Alpha Centauri C, and is 2.18° to the southwest of the Alpha Centauri AB pair. It is currently 12,950 AU (0.2 ly) from AB, which it orbits with a period of about 550,000 years. Its Latin name means the 'nearest star of Centaurus'.

Proxima Centauri is a red dwarf star with a mass about 12.5% of the Sun's mass (M_☉), and average density about 33 times that of the Sun. Because of Proxima Centauri's proximity to Earth, its angular diameter can be measured directly. Its actual diameter is about one-seventh (14%) the diameter of the Sun. Although it has a very low average luminosity, Proxima Centauri is a flare star that randomly undergoes dramatic increases in brightness because of magnetic activity. The star's magnetic field is created by convection throughout the stellar body, and the resulting flare activity generates a total X-ray emission similar to that produced by the Sun. The internal mixing of its fuel by convection through its core and Proxima's relatively low energy-production rate, mean that it will be a main-sequence star for another four trillion years.

The company ASTELCO Systems is a manufacturer of telescopes, telescope control systems, domes/enclosures and related technology for professional astronomical research or public use. ASTELCO is located in Sauerlach near Munich and was founded in 2004.

The company built the telescope and mount of the TRAPPIST Telescopes, famous for the discovery of the TRAPPIST-1 system, a red dwarf with seven terrestrial planets. The company also built the telescopes and mounts for the SPECULOOS Southern and Northern Observatory, which are searching for terrestrial planets around ultracool dwarfs and brown dwarfs in the habitable zone. Other projects include the 60 cm Robotic Telescope BOOTES-5 in Mexico, the COATLI robotic 50 cm telescope in Sierra San Pedro Mártir and the prototype for ESO VLT Laser Guide Star Telescope.

The following nearest bright stars are found within 15.0 parsecs (48.9 ly) of the closest star, the Sun, and have an absolute magnitude of +8.5 or brighter, which is approximately comparable to a listing of stars more luminous than a red dwarf. Right ascension and declination coordinates are for the epoch J2000. The distance measurements are based on the Hipparcos Catalogue and other astrometric data. In the event of a spectroscopic binary, the combined spectral type and absolute magnitude are listed in italics.