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Proxima Centauri d (also called Proxima d) is a candidate
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 ...
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 ...
, the closest star to the Sun and part of the
Alpha Centauri Alpha Centauri ( Latinized from α Centauri and often abbreviated Alpha Cen or α Cen) is a triple star system in the constellation of Centaurus. It consists of 3 stars: Alpha Centauri A (officially Rigil Kentaurus), Alpha Centaur ...
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 ...
. Together with two other planets in the Proxima Centauri system, it is the closest known exoplanet to the Solar System, located approximately away in the constellation of Centaurus. The first signs of the exoplanet emerged as a weak 5.15-day signal in
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 taken from the Very Large Telescope during a 2020 study on Proxima b's mass. This signal was formally proposed to be a candidate exoplanet by Faria et al. in a follow-up paper published in February 2022. Proxima d is a
sub-Earth A sub-Earth is a planet "substantially less massive" than Earth and Venus. In the Solar System, this category includes Mercury and Mars. Sub-Earth exoplanets are among the most difficult type to detect because their small sizes and masses prod ...
at least one-quarter of the
mass of Earth An Earth mass (denoted as M_\mathrm or M_\oplus, where ⊕ is the standard astronomical symbol for Earth), is a unit of mass equal to the mass of the planet Earth. The current best estimate for the mass of Earth is , with a relative uncertain ...
(or twice the mass of Mars), orbiting at roughly every 5.1 days. It is the least massive and innermost known planet of the Proxima Centauri system. It is the least massive exoplanet detected with the radial velocity method . Proxima d orbits too close to its star to be habitable, and receives about 190% of Earth's irradiation—assuming an Earth-like reflectivity, its equilibrium temperature may reach .


See also

* List of nearest exoplanets


References

{{Sky, 14, 29, 42.9487, -, 62, 40, 46.141, 4.243 Exoplanets discovered in 2022 Exoplanets detected by radial velocity Proxima Centauri