List of nearest terrestrial exoplanet candidates

Last updated

This list of nearest terrestrial exoplanet candidates contains possible terrestrial ("rocky") exoplanets spaced at a distance of up to 50 light-years from the Solar System, ordered by increasing distance. [1] [2] [3]

Contents

They may be composed primarily of silicate rocks and/or metals. Within the Solar System, the terrestrial planets are the inner planets closest to the Sun.

Exoplanets discovered (incomplete)

This list is incomplete, currently containing 34 exoplanets, 11 of which probably lie inside their star's habitable zone.

There are roughly 2,000 stars at a distance of up to 50 light-years from the Solar System [4] (64 of them are yellow-orange "G" stars like the Sun [5] ). As many as 15% of them could have Earth-sized planets in the habitable zones. [6]

On November 4, 2013, astronomers reported, based on Kepler space mission data, that there could be as many as 40 billion Earth-sized planets orbiting in the habitable zones of Sun-like stars and red dwarf stars within the Milky Way galaxy. [7] [8] Eleven billion of these estimated planets may be orbiting Sun-like stars. [9] The nearest such planet was then as close as 12 light-years away [7] [8] but (see below) is now estimated slightly above four light-years away.

On August 24, 2016, astronomers announced the discovery of a rocky planet in the habitable zone of Proxima Centauri, the closest star to Earth (not counting the Sun). Called Proxima b, the planet is 1.3 times the mass of Earth and has an orbital period of roughly 11.2 Earth days. [10] However, Proxima Centauri's classification as a red dwarf casts doubts on the habitability of any exoplanets in its orbit due to low stellar flux, high probability of tidal locking, small circumstellar habitable zones and high stellar variation. Another likely candidate is Alpha Centauri, Earth's nearest Sun-like star system 4.37 light-years away. Estimates place the probability of finding a habitable planet around Alpha Centauri A or B at roughly 75%. [11] Alpha Centauri is the target of several exoplanet-finding missions, including Breakthrough Starshot and Mission Centaur, the latter of which is chronicled in the 2016 documentary film The Search for Earth Proxima. [12]

In 2023, astronomers used the radial velocity method to confirm that the exoplanet Wolf 1069 b sits in the habitable zone of Wolf 1069. Located 31 light years from Earth, this planet is 1.26 times the mass of Earth and has a radius of 1.08 times the Earth's. Though Wolf 1069 b is likely tidally locked, its daylight side may still be habitable. It has similar characteristics to Proxima Centauri b and is one of the nearest discovered potentially habitable exoplanets to Earth. Wolf 1069 b is likely rocky, with an Earth-like composition, and climate models suggest that it is habitable for a broad range of possible atmospheres although the nature of its true atmosphere is unknown. Characterizing its atmosphere is more difficult than with a transiting exoplanet as transmission spectroscopy is inapplicable, and instruments for alternative techniques such as analysis of thermal emission and reflected light are not yet available. The angular separation between Wolf 1069 b and its star is also small, which further complicates these measurements. [13] [14] [15]

Data Table

Note: There is no scientific consensus about terrestrial composition of most of the planets in the list. Sources in the "Main source" column confirm the possibility of terrestrial composition.

In September 2012, the discovery of two planets orbiting Gliese 163 [40] was announced. [41] [42] One of the planets, Gliese 163 c, about 6.9 times the mass of Earth and somewhat hotter, was considered to be within the habitable zone, but is probably not terrestrial. [41] [42]

In May 2016, the finding of three Earth-like planets of ultracool dwarf TRAPPIST-1 has been released.

The existence of the planet Gliese 832 c was refuted in 2022, when a study found that the radial velocity signal shows characteristics of a signal originating from stellar activity, and not from a planet.

Statistics

Distance from the Solar System
DistanceLying within
the habitable zone		All
< 10 light-years0 (2?)2
< 20 light-years615
< 30 light-years822
< 40 light-years1024
< 50 light-years1131

Note: in most cases the composition of the atmosphere and atmosphere pressure of exoplanets are unknown, so surface temperatures are estimates based on computer models and expert opinions.

See also

Related Research Articles

<span class="mw-page-title-main">Proxima Centauri</span> Nearest star to the Solar System

Proxima Centauri is the nearest star to Earth after the Sun, located 4.25 light-years away in the southern constellation of Centaurus. This object was 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. Its Latin name means the 'nearest [star] of Centaurus'. 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.

GJ 1061 is a red dwarf star located 12 light-years from Earth in the southern constellation of Horologium. Even though it is a relatively nearby star, it has an apparent visual magnitude of about 13, so it can only be seen with at least a moderately-sized telescope.

Gliese 581 is a red dwarf star of spectral type M3V which hosts a planetary system, 20.5 light-years away from Earth in the Libra constellation. Its estimated mass is about a third of that of the Sun, and it is the 101st closest known star system to the Sun. Gliese 581 is one of the oldest, least active M dwarfs known. Its low stellar activity improves the likelihood of its planets retaining significant atmospheres, and lessens the sterilizing impact of stellar flares.

<span class="mw-page-title-main">Gliese 581d</span> Contested super-Earth orbiting Gliese 581

Gliese 581d is a doubtful, and frequently disputed, exoplanet candidate orbiting within the Gliese 581 system, approximately 20.4 light-years away in the Libra constellation. It was the third planet claimed in the system and the fourth or fifth in order from the star. Multiple subsequent studies found that the planetary signal in fact originates from stellar activity, and thus the planet does not exist, but this remains disputed.

<span class="mw-page-title-main">Super-Earth</span> Type of exoplanet

A Super-Earth or super-terran or super-tellurianis a type of exoplanet with a mass higher than Earth's, but substantially below those of the Solar System's ice giants, Uranus and Neptune, which are 14.5 and 17.1 times Earth's, respectively. The term "super-Earth" refers only to the mass of the planet, and so does not imply anything about the surface conditions or habitability. The alternative term "gas dwarfs" may be more accurate for those at the higher end of the mass scale, although "mini-Neptunes" is a more common term.

Gliese 433 is a dim red dwarf star with multiple exoplanetary companions, located in the equatorial constellation of Hydra. The system is located at a distance of 29.6 light-years from the Sun based on parallax measurements, and it is receding with a radial velocity of +18 km/s. Based on its motion through space, this is an old disk star. It is too faint to be viewed with the naked eye, having an apparent visual magnitude of 9.81 and an absolute magnitude of 10.07.

<span class="mw-page-title-main">Discoveries of exoplanets</span> Detecting planets located outside the Solar System

An exoplanet is a planet located outside the Solar System. The first evidence of an exoplanet was noted as early as 1917, but was not recognized as such until 2016; no planet discovery has yet come from that evidence. What turned out to be the first detection of an exoplanet was published among a list of possible candidates in 1988, though not confirmed until 2003. The first confirmed detection came in 1992, with the discovery of terrestrial-mass planets orbiting the pulsar PSR B1257+12. The first confirmation of an exoplanet orbiting a main-sequence star was made in 1995, when a giant planet was found in a four-day orbit around the nearby star 51 Pegasi. Some exoplanets have been imaged directly by telescopes, but the vast majority have been detected through indirect methods, such as the transit method and the radial-velocity method. As of 24 July 2024, there are 7,026 confirmed exoplanets in 4,949 planetary systems, with 1007 systems having more than one planet. This is a list of the most notable discoveries.

<span class="mw-page-title-main">Gliese 163</span> Red dwarf star in the constellation Dorado

Gliese 163 is a faint red dwarf star with multiple exoplanetary companions in the southern constellation of Dorado. Other stellar catalog names for it include HIP 19394 and LHS 188. It is too faint to be visible to the naked eye, having an apparent visual magnitude of 11.79 and an absolute magnitude of 10.91. This system is located at a distance of 49.4 light-years from the Sun based on parallax measurements. Judging by its space velocity components, it is most likely a thick disk star.

Gliese 180, is a small red dwarf star in the equatorial constellation of Eridanus. It is invisible to the naked eye with an apparent visual magnitude of 10.9. The star is located at a distance of 39 light years from the Sun based on parallax, and is drifting closer with a radial velocity of −14.6 km/s. It has a high proper motion, traversing the sky at the rate of 0.765 arcseconds per year.

Mikko Tuomi is a Finnish astronomer from the University of Hertfordshire, most known for his contributions to the discovery of a number of exoplanets, among them the Proxima Centauri b which orbits the closest star to the Sun. Mikko Tuomi was the first to find indications of the existence of Proxima Centauri b in archival observation data. Other exoplanets to whose discovery or study Tuomi has contributed include HD 40307, HD 154857 c, Kapteyn c, Gliese 682 c, HD 154857, Gliese 221, Gliese 581 g and the planetary system orbiting Tau Ceti. He has led the development of new data analysis techniques for distinguishing observations caused by natural activity of the star and those caused by planets orbiting them.

Gliese 536 b also known as GJ 536 b is a nearby Super-Earth sized exoplanet orbiting interior to the circumstellar habitable zone of the red dwarf (M1) star Gliese 536 every 8.7 days. Due to its short orbital period it could help with future studies of biological activity on exoplanets.

Luyten b is a confirmed exoplanet, likely rocky, orbiting within the habitable zone of the nearby red dwarf Luyten's Star. It is the fourth-closest potentially habitable exoplanet known, at a distance of 12 light-years. Only Proxima Centauri b, Ross 128 b, and GJ 1061 d are closer. Discovered alongside Gliese 273c in June 2017, Luyten b is a super-Earth of around 2.89 times the mass of Earth and receives only 6% more starlight than Earth, making it one of the best candidates for habitability.

Teegarden's Star c is an exoplanet found orbiting in the habitable zone of Teegarden's Star, an M-type red dwarf star 12.5 light years away from the Solar System. It orbits in the conservative habitable zone around its star. Along with Teegarden's Star b, it is among the closest known potentially habitable exoplanets. It was discovered in June 2019.

<span class="mw-page-title-main">Gliese 357</span> Red dwarf with low starspot activity in the Hydra constellation

GJ 357 is an M-type main sequence star with an unusually low star spot activity. It is located 31 light-years from the Solar System, in the Hydra constellation.

<span class="mw-page-title-main">HD 189567</span> Star in the constellation Pavo

HD 189567 is a star with a pair of orbiting exoplanets, located in the southern constellation of Pavo. It is also known as Gliese 776, CD-67 2385, and HR 7644. The star has an apparent visual magnitude of 6.07, which is bright enough for it to be dimly visible to the naked eye. It lies at a distance of 58 light years from the Sun based on parallax measurements, but is drifting closer with a radial velocity of −10.5 km/s.

<span class="mw-page-title-main">GJ 1002</span> Red dwarf star in the constellation Cetus

GJ 1002 is a nearby red dwarf star, located 15.8 light-years away from the Solar System in the constellation of Cetus. The star has 12% the mass and 14% the radius of the Sun, and a temperature of 3,024 K. It hosts a system of two known exoplanets.

LP 890-9, also known as SPECULOOS-2 or TOI-4306, is a high proper motion red dwarf star located 105 light-years (32 pc) away from the Solar System in the constellation of Eridanus. The star has 12% the mass and 15% the radius of the Sun, and a temperature of 2,871 K. It is extremely faint and, with an apparent magnitude of 18, is the faintest star with exoplanets discovered by the Transiting Exoplanet Survey Satellite.

<span class="mw-page-title-main">Wolf 1069</span> Red dwarf star in the constellation Cygnus

Wolf 1069 is a red dwarf star located 31.2 light-years away from the Solar System in the constellation of Cygnus. The star has 17% the mass and 18% the radius of the Sun, a temperature of 3,158 K, and a slow rotation period of 150–170 days. It hosts one known exoplanet called Wolf 1069 b which could possibly sustain life.

References

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