Proxima Centauri c (also called Proxima c or Alpha Centauri Cc) is a controversial

exoplanet An exoplanet or extrasolar planet is a planet outside the Solar System. The first possible evidence of an exoplanet was noted in 1917 but was not recognized as such. The first confirmation of detection occurred in 1992. A different planet, init ...

candidate claimed to be orbiting the

red dwarf ''Red Dwarf'' is a British science fiction comedy franchise created by Rob Grant and Doug Naylor, which primarily consists of a television sitcom that aired on BBC Two between 1988 and 1999, and on Dave since 2009, gaining a cult following. T ...

star

Proxima Centauri Proxima Centauri is a small, low-mass star located away from the Sun in the southern constellation of Centaurus. Its Latin name means the 'nearest tarof Centaurus'. It was discovered in 1915 by Robert Innes and is the nearest-kno ...

, which is the closest star to the Sun and part of a triple

star system A star system or stellar system is a small number of stars that orbit each other, bound by gravitational attraction. A large group of stars bound by gravitation is generally called a '' star cluster'' or '' galaxy'', although, broadly speak ...

. It is located approximately from Earth in the constellation of Centaurus, making it, Proxima b, and Proxima d the closest known exoplanets to the Solar System. Proxima Centauri c is a super-Earth or mini-Neptune about 7 times as massive as Earth, orbiting at roughly every . Due to its large mass and its distance from Proxima Centauri, the exoplanet is uninhabitable, with an equilibrium temperature of approximately . The planet is not transiting its parent star from the point of view of an Earth-based observer. The planet was first reported by Italian astrophysicist Mario Damasso and his colleagues in April 2019. Damasso's team had noticed minor movements of Proxima Centauri in the

radial velocity The radial velocity or line-of-sight velocity, also known as radial speed or range rate, of a target with respect to an observer is the temporal rate of change, rate of change of the distance or Slant range, range between the two points. It is e ...

data from the ESO's HARPS instrument, indicating a possible second planet orbiting Proxima Centauri. The discovery was published in January 2020. In June 2020, the planet's existence was initially confirmed using

Hubble The Hubble Space Telescope (often referred to as HST or Hubble) is a space telescope that was launched into low Earth orbit in 1990 and remains in operation. It was not the first space telescope, but it is one of the largest and most versa ...

astrometry Astrometry is a branch of astronomy that involves precise measurements of the positions and movements of stars and other celestial bodies. It provides the kinematics and physical origin of the Solar System and this galaxy, the Milky Way. His ...

data from , allowing its inclination and true mass to be determined. Also in June 2020, a possible directly imaged counterpart of Proxima c was detected in the infrared with SPHERE, but the authors admit that they "did not obtain a clear detection". If their candidate source is in fact Proxima Centauri c, it is too bright for a planet of its mass and age, implying that the planet may have a ring system with a radius of around 5 . However, a 2022 study questioned the planetary nature of the observed

signal corresponding to Proxima c, attributing it to systematic effects. If this is the case, it is unclear why astrometric observations detected what appeared to be a similar planetary signature.

References

{{Sky, 14, 29, 42.9487, -, 62, 40, 46.141, 4.243 Exoplanets discovered in 2020 Exoplanets detected by radial velocity Exoplanets detected by astrometry Proxima Centauri Planetary rings Exoplanet candidates

See also

References