Alpha Centauri - wikipedia Alpha Centauri This article is about `` α Centauri ''. For `` a Centauri '', see HD 125823. For `` A Centauri '', see A Centauri. For other uses, see Alpha Centauri ( disambiguation ). `` Toliman '' redirects here. For other uses, see Toliman ( disambiguation ). Alpha Centauri α Centauri AB is the bright star to the left, with Proxima Centauri circled in red. The bright star to the right is β Centauri Observation data Epoch J2000. 0 Equinox J2000. 0 Constellation Centaurus Alpha Centauri A Right ascension 14 39 36.49400 Declination -- 60 ° 50 ′ 02.3737 '' Apparent magnitude ( V ) + 0.01 Alpha Centauri B Right ascension 14 39 35.06311 Declination -- 60 ° 50 ′ 15.0992 '' Apparent magnitude ( V ) + 1.33 Characteristics Spectral type G2V U − B colour index + 0.24 B − V colour index + 0.71 Spectral type K1V U − B colour index + 0.68 B − V colour index + 0.88 Astrometry Radial velocity ( R ) 2998786000000000000 ♠ − 21.4 ± 0.76 km / s Proper motion ( μ ) RA : − 3679.25 mas / yr Dec. : 473.67 mas / yr Parallax ( π ) 754.81 ± 4.11 mas Distance 4.37 ly Absolute magnitude ( M ) 4.38 Radial velocity ( R ) 2998814000000000000 ♠ − 18.6 ± 1.64 km / s Proper motion ( μ ) RA : − 3614.39 mas / yr Dec. : 802.98 mas / yr Parallax ( π ) 754.81 ± 4.11 mas Distance 4.37 ly Absolute magnitude ( M ) 5.71 Details Alpha Centauri A Mass 1.100 M Radius 7000122340000000000 ♠ 1.2234 ± 0.0053 R Luminosity 1.519 L Surface gravity ( log g ) 4.30 cgs Temperature 5,790 K Metallicity ( Fe / H ) 0.20 dex Rotation 22 days Age ≈ 4.4 Gyr Alpha Centauri B Mass 0.907 M Radius 6999863200000000000 ♠ 0.8632 ± 0.0037 R Luminosity 0.5002 L Surface gravity ( log g ) 4.37 cgs Temperature 5,260 K Metallicity 0.23 Rotation 41 days Age ≈ 6.5 Gyr Orbit Primary Companion Period ( P ) 7001799100000000000 ♠ 79.91 ± 0.011 yr Semi-major axis ( a ) 7001175700000000000 ♠ 17.57 ± 0.022 '' Eccentricity ( e ) 6999517900000000000 ♠ 0.5179 ± 0.000 76 Inclination ( i ) 7001792050000000000 ♠ 79.205 ± 0.041 ° Longitude of the node ( Ω ) 7002204850000000000 ♠ 204.85 ± 0.084 ° Periastron epoch ( T ) 7003187566000000000 ♠ 1875. 66 ± 0.012 Argument of periastron ( ω ) ( secondary ) 7002231650000000000 ♠ 231.65 ± 0.076 ° Other designations Toliman, Bungula, Gliese 559, FK5 538, CD − 60 ° 5483, CCDM J14396 - 6050, GC 19728 α Cen A : Rigil Kentaurus, Rigil Kent, α Centauri, HR 5459, HD 128620, GCTP 3309.00, LHS 50, SAO 252838, HIP 71683 α Cen B : α Centauri, HR 5460, HD 128621, LHS 51, HIP 71681 Database references SIMBAD AB Exoplanet Archive data ARICNS data Extrasolar Planets Encyclopaedia data Alpha Centauri ( α Centauri, abbreviated Alf Cen, α Cen ) is the closest star system to the Solar System, being 4.37 light - years ( 1.34 pc ) from the Sun. It consists of three stars : Alpha Centauri A ( also named Rigil Kentaurus ) and Alpha Centauri B, which form the binary star Alpha Centauri AB, and a small and faint red dwarf, Alpha Centauri C ( also named Proxima Centauri ), which is loosely gravitationally bound and orbiting the other two at a current distance of about 13,000 astronomical units ( 0.21 ly ). To the unaided eye, the two main components appear as a single point of light with an apparent visual magnitude of − 0.27, forming the brightest star in the southern constellation of Centaurus and is the third - brightest star in the night sky, outshone only by Sirius and Canopus. Alpha Centauri A ( α Cen A ) has 1.1 times the mass and 1.519 times the luminosity of the Sun, while Alpha Centauri B ( α Cen B) is smaller and cooler, at 0.907 times the Sun 's mass and 0.445 times its visual luminosity. During the pair 's 79.91 - year orbit about a common centre, the distance between them varies from nearly that between Pluto and the Sun ( 35.6 AU ) to that between Saturn and the Sun ( 11.2 AU ). Proxima Centauri ( α Cen C ) is at the slightly smaller distance of 4.24 light - years ( 1.30 pc ) from the Sun, making it the closest star to the Sun, even though it is not visible to the naked eye. The separation of Proxima from Alpha Centauri AB is about 13,000 astronomical units ( 0.21 ly ), equivalent to about 430 times the size of Neptune 's orbit. Proxima Centauri b, an Earth - sized exoplanet in the habitable zone of Proxima Centauri, was discovered in 2016. Contents 1 Nomenclature 2 Nature and components 2.1 Alpha Centauri A 2.2 Alpha Centauri B 2.3 Alpha Centauri C ( Proxima Centauri ) 3 Observation 4 Observational history 5 Binary system 5.1 Proxima Centauri 6 Kinematics 6.1 Predicted future changes 7 Planets 7.1 Proxima Centauri b 7.2 Alpha Centauri Bb & Bc 7.3 Possible detection of another planet 7.4 Possibility of additional planets 7.5 Theoretical planets 7.6 Circumstellar discs 8 View from this system 8.1 From Proxima Centauri b 8.2 From a hypothetical A or B planet 9 Other names 10 Exploration 11 Distance 12 See also 13 Notes 14 References 15 External links 15.1 Hypothetical planets or exploration Nomenclature α Centauri ( Latinised to Alpha Centauri ) is the system 's Bayer designation. It bore the traditional name Rigil Kentaurus, which is a latinisation of the Arabic name رجل القنطورس ‎ Rijl al - Qanṭūris, meaning `` Foot of the Centaur ''. Alpha Centauri C was discovered in 1915 by the Scottish astronomer Robert Innes, Director of the Union Observatory in Johannesburg, South Africa, who suggested that it be named Proxima Centauri ( actually Proxima Centaurus ). The name is from Latin, meaning ' nearest ( star ) of Centaurus '. In 2016, the International Astronomical Union organized a Working Group on Star Names ( WGSN ) to catalog and standardize proper names for stars. The WGSN states that in the case of multiple stars the name should be understood to be attributed to the brightest component by visual brightness. The WGSN approved the name Proxima Centauri for Alpha Centauri C on 21 August 2016 and the name Rigil Kentaurus for Alpha Centauri A on 6 November 2016. They are now both so included in the List of IAU - approved Star Names. Nature and components The relative sizes and colours of stars in the Alpha Centauri system, compared to the Sun Alpha Centauri is the name given to what appears as a single star to the naked eye and the brightest star in the southern constellation of Centaurus. At − 0.27 apparent visual magnitude ( calculated from A and B magnitudes ), it is fainter only than Sirius and Canopus. The next - brightest star in the night sky is Arcturus. Alpha Centauri is a multiple - star system, with its two main stars being Alpha Centauri A ( α Cen A ) and Alpha Centauri B ( α Cen B ), usually defined to identify them as the different components of the binary α Cen AB. A third companion -- Proxima Centauri ( or Proxima or α Cen C ) -- is much further away than the distance between stars A and B, but is still gravitationally associated with the AB system. As viewed from Earth, it is located at an angular separation of 2.2 ° from the two main stars. Proxima Centauri would appear to the naked eye as a separate star from α Cen AB if it were bright enough to be seen without a telescope. Alpha Centauri AB and Proxima Centauri form a visual double star. Together, the three components make a triple star system, referred to by double - star observers as the triple star ( or multiple star ), α Cen AB - C. Together, the bright visible components of the binary star system are called Alpha Centauri AB ( α Cen AB ). This `` AB '' designation denotes the apparent gravitational centre of the main binary system relative to other companion star ( s ) in any multiple star system. `` AB - C '' refers to the orbit of Proxima around the central binary, being the distance between the centre of gravity and the outlying companion. Some older references use the confusing and now discontinued designation of A × B. Because the distance between the Sun and Alpha Centauri AB does not differ significantly from either star, gravitationally this binary system is considered as if it were one object. Asteroseismic studies, chromospheric activity, and stellar rotation ( gyrochronology ), are all consistent with the α Cen system being similar in age to, or slightly older than, the Sun, with typical ages quoted between 4.5 and 7 billion years ( Gyr ). Asteroseismic analyses that incorporate the tight observational constraints on the stellar parameters for α Cen A and / or B have yielded age estimates of 7000484999999999999 ♠ 4.85 ± 0.5 Gyr, 7000500000000000000 ♠ 5.0 ± 0.5 Gyr, 5.2 -- 7.1 Gyr, 6.4 Gyr, and 7000652000000000000 ♠ 6.52 ± 0.3 Gyr. Age estimates for stars A and B based on chromospheric activity ( Calcium H & K emission ) yield 4.4 -- 6.5 Gyr, whereas gyrochronology yields 7000500000000000000 ♠ 5.0 ± 0.3 Gyr. Alpha Centauri a Alpha Centauri A, also known as Rigil Kentaurus, is the principal member, or primary, of the binary system, being slightly larger and more luminous than the Sun. It is a solar - like main - sequence star with a similar yellowish colour, whose stellar classification is spectral type G2 V. From the determined mutual orbital parameters, Alpha Centauri A is about 10 percent more massive than the Sun, with a radius about 22 percent larger. The projected rotational velocity ( v sin i ) of this star is 7003270000000000000 ♠ 2.7 ± 0.7 km / s, resulting in an estimated rotational period of 22 days, which gives it a slightly faster rotational period than the Sun 's 25 days. When considered among the individual brightest stars in the sky ( excluding the Sun ), Alpha Centauri A is the fourth brightest at an apparent visual magnitude of + 0.01, being fractionally fainter than Arcturus at an apparent visual magnitude of − 0.04. Alpha Centauri B Alpha Centauri B is the companion star, or secondary, of the binary system, and is slightly smaller and less luminous than the Sun. It is a main - sequence star of spectral type K1 V, making it more an orange colour than the primary star. Alpha Centauri B is about 90 percent the mass of the Sun and 14 percent smaller in radius. The projected rotational velocity ( v sin i ) is 7003110000000000000 ♠ 1.1 ± 0.8 km / s, resulting in an estimated rotational period of 41 days. ( An earlier, 1995 estimate gave a similar rotation period of 36.8 days. ) Although it has a lower luminosity than component A, star B emits more energy in the X-ray band. The light curve of B varies on a short time scale and there has been at least one observed flare. Alpha Centauri B at an apparent visual magnitude of 1.33 would be twenty - first in brightness if it could be seen independently of Alpha Centauri A. Alpha Centauri C ( Proxima Centauri ) Alpha Centauri C, also known as Proxima Centauri, is of spectral class M6 Ve, a small main - sequence star ( Type V ) with emission lines. Its B − V colour index is + 1.82 and its mass is about 0.123 solar masses ( M ), or 129 Jupiter masses. Observation Location of Alpha Centauri in Centaurus The two stars of the binary Alpha Centauri AB are too close together to be resolved by the naked eye, as apparent angular separation varies over about 80 years between 2 and 22 arcsec ( the naked eye has a resolution of 60 arcsec ), but through much of the orbit, both are easily resolved in binoculars or small 5 cm ( 2 in ) telescopes. In the southern hemisphere, Alpha Centauri forms the outer star of The Pointers or The Southern Pointers, so called because the line through Beta Centauri ( Hadar / Agena ), some 4.5 ° west, points directly to the constellation Crux -- the Southern Cross. The Pointers easily distinguish the true Southern Cross from the fainter asterism known as the False Cross. The two bright stars at the lower right are Alpha ( right ) and Beta Centauri ( left, above antenna ). A line drawn through them points to the four bright stars of the Southern Cross, just to the right of the dome of La Silla Observatory. Alpha Centauri taken in daylight by holding a Canon Powershot S100 behind the eyepiece of a 110mm refractor. The photo is one of the best frames of a video. The double star is clearly visible. South of about 29 ° S latitude, Alpha Centauri is circumpolar and never sets below the horizon. Both stars and Crux are too far south to be visible for mid-latitude northern observers. Below about 29 ° N latitude to the equator ( roughly Hermosillo, Chihuahua City in Mexico, Galveston, Texas, Ocala, Florida and Lanzarote, the Canary Islands of Spain ) during the northern summer, Alpha Centauri lies close to the southern horizon. The star culminates each year at midnight on 24 April or 9 p.m. on 8 June. As seen from Earth, Proxima Centauri is 2.2 ° southwest from Alpha Centauri AB. This is about four times the angular diameter of the Full Moon, and almost exactly half the distance between Alpha Centauri AB and Beta Centauri. Proxima usually appears as a deep - red star of an apparent visual magnitude of 11.1 in a sparsely populated star field, requiring moderately sized telescopes to see. Listed as V645 Cen in the General Catalogue of Variable Stars ( G.C.V.S. ) Version 4.2, this UV Ceti - type flare star can unexpectedly brighten rapidly by as much as 0.6 magnitudes at visual wavelengths, then fade after only a few minutes. Some amateur and professional astronomers regularly monitor for outbursts using either optical or radio telescopes. In August 2015 the largest recorded flares of the star occurred, with the star becoming 8.3 times brighter than normal on 13 August, in the B band ( blue light region ). Observational History View of Alpha Centauri from the Digitized Sky Survey 2 Alpha Centauri was listed in the 2nd - century star catalog of Ptolemy. He gives the ecliptic coordinates, but texts differ as to whether the ecliptic latitude reads 44 ° 10 ′ South or 41 ° 10 ′ South. ( Presently the ecliptic latitude is 43.5 ° South but it has decreased by a fraction of a degree since Ptolemy 's time due to proper motion. ) In Ptolemy 's time Alpha Centauri was visible from his city of Alexandria, Egypt, at 31 ° N, but due to precession its declination is now -- 60 ° 51 ′ South and it can no longer be seen at that latitude. English explorer Robert Hues brought Alpha Centauri to the attention of European observers in his 1592 work Tractatus de Globis, along with Canopus and Achernar, noting `` Now, therefore, there are but three Stars of the first magnitude that I could perceive in all those parts which are never seene here in England. The first of these is that bright Star in the sterne of Argo which they call Canobus. The second is in the end of Eridanus. The third ( Alpha Centauri ) is in the right foote of the Centaure. '' The binary nature of Alpha Centauri AB was first recognized in December 1689 by astronomer and Jesuit priest Jean Richaud. The finding was made incidentally while observing a passing comet from his station in Puducherry. Alpha Centauri was only the second binary star system to be discovered, preceded by Alpha Crucis. By 1752, French astronomer Nicolas Louis de Lacaille made astrometric positional measurements using state - of - the - art instruments of that time. Its large proper motion was discovered by Manuel John Johnson, observing from Saint Helena, who informed Thomas Henderson at the Royal Observatory, Cape of Good Hope of it. The parallax of Alpha Centauri was subsequently determined by Henderson from many exacting positional observations of the AB system between April 1832 and May 1833. He withheld his results, however, because he suspected they were too large to be true, but eventually published them in 1839 after Friedrich Wilhelm Bessel released his own accurately determined parallax for 61 Cygni in 1838. For this reason, Alpha Centauri is sometimes considered as the second star to have its distance measured because Henderson 's work was not fully recognized at first. ( The distance of Alpha is now reckoned at 4.396 ly or 41.59 trillion km. ) Later, John Herschel made the first micrometrical observations in 1834. Since the early 20th century, measures have been made with photographic plates. Compared to the Sun, Alpha Centauri A is of the same stellar type G2, while Alpha Centauri B is a K1 - type star. By 1926, South African astronomer William Stephen Finsen calculated the approximate orbit elements close to those now accepted for this system. All future positions are now sufficiently accurate for visual observers to determine the relative places of the stars from a binary star ephemeris. Others, like the Belgian astronomer D. Pourbaix ( 2002 ), have regularly refined the precision of any new published orbital elements. Alpha Centauri is inside the G - cloud, and the nearest known system to it is the binary brown dwarf system Luhman 16 at 3.6 ly ( 1.1 pc ). Scottish astronomer Robert T.A. Innes discovered Proxima Centauri in 1915 by blinking photographic plates taken at different times during a dedicated proper motion survey. This showed the large proper motion and parallax of the star was similar in both size and direction to those of Alpha Centauri AB, suggesting immediately it was part of the system and slightly closer to Earth than Alpha Centauri AB. Lying 4.24 ly ( 1.30 pc ) away, Proxima Centauri is the nearest star to the Sun. All current derived distances for the three stars are from the parallaxes obtained from the Hipparcos star catalogue ( HIP ) and the Hubble Space Telescope. Binary system Apparent and true orbits of Alpha Centauri. The A component is held stationary and the relative orbital motion of the B component is shown. The apparent orbit ( thin ellipse ) is the shape of the orbit as seen by an observer on Earth. The true orbit is the shape of the orbit viewed perpendicular to the plane of the orbital motion. According to the radial velocity vs. time the radial separation of A and B along the line of sight had reached a maximum in 2007 with B being behind A. The orbit is divided here into 80 points, each step refers to a timestep of approx. 0.99888 years or 364.84 days. With the orbital period of 79.91 years, the A and B components of this binary star can approach each other to 11.2 AU ( 1.68 billion km ), or about the mean distance between the Sun and Saturn ; and may recede as far as 35.6 AU ( 5.33 billion km ), approximately the distance from the Sun to Pluto. This is a consequence of the binary 's moderate orbital eccentricity e = 0.5179. From the orbital elements, the total mass of both stars is about 2.0 M -- or twice that of the Sun. The average individual stellar masses are 1.09 M and 0.90 M, respectively, though slightly higher masses have been quoted in recent years, such as 1.14 M and 0.92 M, or totalling 2.06 M. Alpha Centauri A and B have absolute magnitudes of + 4.38 and + 5.71, respectively. Stellar evolution theory implies both stars are slightly older than the Sun at 5 to 6 billion years, as derived by both mass and their spectral characteristics. Viewed from Earth, the apparent orbit of this binary star means that its separation and position angle ( PA ) are in continuous change throughout its projected orbit. Observed stellar positions in 2010 are separated by 6.74 arcsec through the PA of 245.7 °, reducing to 6.04 arcsec through 251.8 ° in 2011. The closest recent approach was in February 2016, at 4.0 arcsec through 300 °. The observed maximum separation of these stars is about 22 arcsec, while the minimum distance is 1.7 arcsec. The widest separation occurred during February 1976 and the next will be in January 2056. In the true orbit, closest approach or periastron was in August 1955, and next in May 2035. Furthest orbital separation at apastron last occurred in May 1995 and the next will be in 2075. The apparent distance between the two stars is rapidly decreasing, at least until 2019. Proxima Centauri Main article : Proxima Centauri The much fainter red dwarf Proxima Centauri, or simply Proxima, is about 13,000 astronomical units ( AU ) away from Alpha Centauri AB. This is equivalent to 0.21 ly or 1.9 trillion km -- about 5 % the distance between Alpha Centauri AB and the Sun. Due to the large distance between Proxima and Alpha, it was long unknown whether they were gravitationally bound. The true orbital speed is necessarily small, and it was necessary to measure the speeds of Proxima and Alpha with a great precision. Otherwise it was impossible to ascertain whether Proxima is bound to Alpha or whether it is a completely unrelated star that happens to be undergoing a close approach at a low relative speed. Probability suggested that such low speed approaches would be rare and unlikely, but it could not be ruled out. It was only in 2017 that a paper by Kervella, et al., showed that, based on high precision radial velocity measurements and with a high degree of confidence, Proxima and Alpha Centauri are in fact gravitationally bound. The orbital period of Proxima is approximately 550,000 years, with an eccentricity of 6999500000000000000 ♠ 0.50 + 0.08 − 0.09. Proxima comes within 7014643270844010000 ♠ 4300 + 1100 − 900 AU of Alpha Centauri AB at periastron, and the apastron occurs at 7015194477231910000 ♠ 13 000 + 300 − 100 AU. Relative positions of Sun, Alpha Centauri AB and Proxima Centauri. Grey dot is projection of Proxima Centauri, located at the same distance as Alpha Centauri AB. Proxima is a red dwarf of spectral class M6 Ve with an absolute magnitude of + 15.60, which is only a small fraction of the Sun 's luminosity. By mass, Proxima is calculated as 6999123000000000000 ♠ 0.123 ± 0.06 M ( rounded to 0.12 M ) or about one - eighth that of the Sun. Kinematics Stars closest to the Sun, including Alpha Centauri ( 25 April 2014 ). All components of Alpha Centauri display significant proper motions against the background sky, similar to the first - magnitude stars Sirius and Arcturus. Over the centuries, this causes the apparent stellar positions to slowly change. Such motions define the high - proper - motion stars. These stellar motions were unknown to ancient astronomers. Most assumed that all stars were immortal and permanently fixed on the celestial sphere, as stated in the works of the philosopher Aristotle. Edmond Halley in 1718 found that some stars had significantly moved from their ancient astrometric positions. For example, the bright star Arcturus ( α Boo ) in the constellation of Boötes showed an almost 0.5 ° difference in 1800 years, as did the brightest star, Sirius, in Canis Major ( α CMa ). Halley 's positional comparison was Ptolemy 's catalogue of stars contained in the Almagest whose original data included portions from an earlier catalogue by Hipparchos during the 1st century BCE. Halley 's proper motions were mostly for northern stars, so the southern star Alpha Centauri was not determined until the early 19th century. Scottish - born observer Thomas Henderson in the 1830s at the Royal Observatory at the Cape of Good Hope discovered the true distance to Alpha Centauri. He soon realized this system was likely to have a high proper motion, In this case, the apparent stellar motion was found using Nicolas Louis de Lacaille 's astrometric observations of 1751 -- 1752, by the observed differences between the two measured positions in different epochs. The proper motion of the centre of mass is about 3620 mas ( milli - arcseconds per year toward the west and 694 mas / y towoard the north, giving an overall motion of 3686 mas / y in a direction 11 ° north of west. The motion of Alpha Centauri is about 6.1 arcmin each century, or 1.02 ° each millennium. These motions are about one - fifth and twice, respectively, the diameter of the full Moon. The velocity in the western direction is 23.0 km / s and in the northerly direction 4.4 km / s. Using spectroscopy the mean radial velocity has been determined to be around 22.4 km / s towards the Solar System. Since α Centauri A and B are almost exactly in the plane of the Milky Way as viewed from here, there are many stars behind them. In early May, 2028, α Centauri A will pass between us and a distant red star. There is a 45 % probability that an Einstein ring may be observed. Other near conjunctions will also happen in the coming decades. These will allow very accurate measurements of the proper motions of the components and may give information on planets. Predicted future changes Distances of the nearest stars from 20,000 years ago until 80,000 years in the future Animation showing the motion of α Centauri through the sky. ( The other stars are held fixed for didactic reasons. ) `` Oggi '' means today. As the stars of Alpha Centauri approach the Solar System, measured common proper motions and trigonometric parallaxes slowly increase. These smaller effects will change until the star system becomes closest to Earth, and begin reversing as the distance increases again. Furthermore, other small changes also occur with the binary star 's orbital elements. For example, in the size of the semi-major axis of the orbital ellipse will increasing by 0.03 arcsec per century. Also the observed position angles of the stars are also subject to small cumulative changes ( additional to position angle changes caused by the Precession of the Equinoxes ), as first determined by W.H. van den Bos in 1926. Apparent motion of Alpha Centauri relative to Beta Centauri. The minimum separation will actually be greater than shown in this figure. Based on knowing these common proper motions and radial velocities, Alpha Centauri will continue to gradually brighten, passing just north of the Southern Cross or Crux, before moving northwest and up towards the present celestial equator and away from the galactic plane. By about 29,700 AD, in the present - day constellation of Hydra, Alpha Centauri will be 1.00 pc or 3.3 ly away., though later calculations suggest 0.90 pc or 2.9 ly in 29,000 AD. Then it will reach the stationary radial velocity ( RVel ) of 0.0 km / s and the maximum apparent magnitude of − 0.86 v ( which is comparable to present - day magnitude of Canopus ). Even during the time of this nearest approach, however, the apparent magnitude of Alpha Centauri will still not surpass that of Sirius, which will brighten incrementally over the next 60,000 years, and will continue to be the brightest star as seen from Earth for the next 210,000 years. About 28,000 years from now, the Alpha Centauri system will then begin to move away from the Solar System, showing a positive radial velocity. Because of visual perspective, these stars will reach a final vanishing point and slowly disappear among the countless stars of the Milky Way. Viewed from the Earth in about AD 6200 Alpha Centaui will appear only about 43 arcmin ( or one and a half diameters of the Moon ) north of Beta Centauri. This will form a brilliant feature in the southern sky. Such a close approach of two first - magnitude stars will not occur again for a very long time. Beta Centauri is in reality far more distant than Alpha Centauri. Planets Proxima Centauri B Main article : Proxima Centauri b In August 2016, the European Southern Observatory announced the discovery of a planet slightly larger than the Earth orbiting Proxima Centauri. Proxima Centauri b was found using the radial velocity method, where periodic Doppler shifts of spectral lines of the host star suggest an orbiting object. From these readings, the radial velocity of the parent star relative to the Earth is varying with an amplitude of about 2 metres ( 6.6 ft ) per second. The planet lies in the habitable zone of Proxima Centauri, but it is possible that the planet is tidally locked to the star, resulting in temperature extremes that would be difficult for life to overcome. Alpha Centauri Bb & Bc Main article : Alpha Centauri Bb In 2012, a planet around Alpha Centauri B was announced, but in 2015 a new analysis concluded that it almost certainly does not exist and was just a spurious artefact of the data analysis. Alpha Centauri Bc was first announced in 2013 by Demory et al. It has an estimated orbital period of approximately 12 Earth days -- smaller than that of Mercury -- with a semimajor axis of 0.10 AU and an eccentricity smaller than 0.24. Possible detection of Another planet On 25 March 2015, a scientific paper by Demory and colleagues published transit results for Alpha Centauri B using the Hubble Space Telescope for a total of 40 hours. They evidenced a transit event possibly corresponding to a planetary body with a radius around 0.92 R. This planet would most likely orbit Alpha Centauri B with an orbital period of 20.4 days or less, with only a 5 percent chance of it having a longer orbit. The median average of the likely orbits is 12.4 days with an impact parameter of around 0 -- 0.3. Its orbit would likely have an eccentricity of 0.24 or less. Like the probably spurious Alpha Centauri Bb, it likely has lakes of molten lava and would be far too close to Alpha Centauri B to harbour life. Possibility of additional planets The discovery of planets orbiting other star systems, including similar binary systems ( Gamma Cephei ), raises the possibility that additional planets may exist in the Alpha Centauri system. Such planets could orbit Alpha Centauri A or Alpha Centauri B individually, or be on large orbits around the binary Alpha Centauri AB. Because both the principal stars are fairly similar to the Sun ( for example, in age and metallicity ), astronomers have been especially interested in making detailed searches for planets in the Alpha Centauri system. Several established planet - hunting teams have used various radial velocity or star transit methods in their searches around these two bright stars. All the observational studies have so far failed to find any evidence for brown dwarfs or gas giants. In 2009, computer simulations showed that a planet might have been able to form near the inner edge of Alpha Centauri B 's habitable zone, which extends from 0.5 to 0.9 AU from the star. Certain special assumptions, such as considering that Alpha Centauri A and B may have initially formed with a wider separation and later moved closer to each other ( as might be possible if they formed in a dense star cluster ) would permit an accretion - friendly environment farther from the star. Bodies around A would be able to orbit at slightly farther distances due to A 's stronger gravity. In addition, the lack of any brown dwarfs or gas giants in close orbits around A or B make the likelihood of terrestrial planets greater than otherwise. Theoretical studies on the detectability via radial velocity analysis have shown that a dedicated campaign of high - cadence observations with a 1 - meter class telescope can reliably detect a hypothetical planet of 1.8 M in the habitable zone of B within three years. Radial velocity measurements of Alpha Centauri B with High Accuracy Radial Velocity Planet Searcher spectrograph ruled out planets of more than 4 M to the distance of the habitable zone of the star ( orbital period P = 200 days ). Current estimates place the probability of finding an earth - like planet around Alpha Centauri A or B at roughly 85 %, although this number remains uncertain. The observational thresholds for planet detection in the habitable zones via the radial velocity method are currently ( 2017 ) estimated to be about 50 M for Alpha Centauri A, 8 M for B, and 0.5 M for Proxima. Theoretical planets Early computer - generated models of planetary formation predicted the existence of terrestrial planets around both Alpha Centauri A and B, but most recent numerical investigations have shown that the gravitational pull of the companion star renders the accretion of planets very difficult. Despite these difficulties, given the similarities to the Sun in spectral types, star type, age and probable stability of the orbits, it has been suggested that this stellar system could hold one of the best possibilities for harbouring extraterrestrial life on a potential planet. In the Solar System both Jupiter and Saturn were probably crucial in perturbing comets into the inner Solar System. Here, the comets provided the inner planets with their own source of water and various other ices. In the Alpha Centauri system, Proxima Centauri may have influenced the planetary disk as the Alpha Centauri system was forming, enriching the area around Alpha Centauri A and B with volatile materials. This would be discounted if, for example, Alpha Centauri B happened to have gas giants orbiting Alpha Centauri A ( or conversely, Alpha Centauri A for Alpha Centauri B ), or if the stars B and A themselves were able to perturb comets into each other 's inner system as Jupiter and Saturn presumably have done in the Solar System. Such icy bodies probably also reside in Oort clouds of other planetary systems, when they are influenced gravitationally by either the gas giants or disruptions by passing nearby stars many of these icy bodies then travel starwards. Such ideas also apply to the close approach of Alpha Centauri or other stars to the Solar System, when in the distant future of our Oort Cloud may be disrupted enough to see increased numbers of active comets. To be in the star 's habitable zone, any suspected planet around Alpha Centauri A would have to be optimally placed about 1.25 AU away -- about halfway between the distances of Earth 's orbit and Mars 's orbit in the Solar System -- so as to have similar planetary temperatures and conditions for liquid water to exist. For the slightly less luminous and cooler Alpha Centauri B, the habitable zone would lie closer at about 0.7 AU ( 100 million km ), approximately the distance that Venus is from the Sun. With the goal of finding evidence of such planets, both Proxima Centauri and Alpha Centauri AB were among the listed `` Tier 1 '' target stars for NASA 's Space Interferometry Mission ( SIM ). Detecting planets as small as three Earth - masses or smaller within two astronomical units of a `` Tier 1 '' target would have been possible with this new instrument. The SIM mission, however, was cancelled due to financial issues in 2010. Circumstellar discs Based on observations between 2007 and 2012, a study found a slight excess of emissions in the 24 μm ( mid / far - infrared ) band surrounding α Centauri AB, which may be interpreted as evidence for a sparse circumstellar disc or dense interplanetary dust. The total mass was estimated to be between 10 to 10 the mass of the Moon, or 10 -- 100 times the mass of the Solar System 's zodiacal cloud. If such a disc existed around both stars, α Centauri A 's disc would likely be stable to 2.8 AU, and α Centauri B 's would likely be stable to 2.5 AU. This would put A 's disc entirely within the frost line, and a small part of B 's outer disc just outside. View from this system Looking towards the sky around Orion from Alpha Centauri with Sirius near Betelgeuse, Procyon in Gemini, and the Sun between Perseus and Cassiopeia generated by Celestia Viewed from near the Alpha Centauri system, the sky would appear very much as it does for an observer on Earth, except that Centaurus would be missing its brightest star. The Sun would be a yellow star of an apparent visual magnitude of + 0.5 in eastern Cassiopeia, at the antipodal point of Alpha Centauri 's current right ascension and declination, at 02 39 35 + 60 ° 50 ′ ( 2000 ). This place is close to the 3.4 - magnitude star ε Cassiopeiae. Because of the placement of the Sun, an interstellar or alien observer would find the / / of Cassiopeia had become a / / / shape nearly in front of the Heart Nebula in Cassiopeia. Sirius lies less than a degree from Betelgeuse in the otherwise unmodified Orion and with a magnitude of − 1.2 is a little fainter than from Earth but still the brightest star in the Alpha Centauri sky. Procyon is also displaced into the middle of Gemini, outshining Pollux, whereas both Vega and Altair are shifted northwestward relative to Deneb ( which barely moves, due to its great distance ), giving the Summer Triangle a more equilateral appearance. From Proxima Centauri B From Proxima Centauri b, Alpha Centauri AB would appear like two close bright stars with the combined apparent magnitude of − 6.8. Depending on the binary 's orbital position, the bright stars would appear noticeably divisible to the naked eye, or occasionally, but briefly, as a single unresolved star. Based on the calculated absolute magnitudes, the visual apparent magnitudes of Alpha Centauri A and B would be − 6.5 and − 5.2, respectively. From a hypothetical a or B planet Artist 's rendition of the view from a hypothetical airless planet orbiting Alpha Centauri A An observer on a hypothetical planet orbiting around either Alpha Centauri A or Alpha Centauri B would see the other star of the binary system as an intensely bright object in the night sky, showing a small but discernible disk while near periapse : A up to 210 arc seconds, B up to 155 arc seconds. Near apoapse, the disc would shrink to 60 arc seconds for A, 43 arc seconds for B, being too small to resolve by naked eye. In any case, the dazzling surface brightness could make the discs harder to resolve than a similarly sized less bright object. For example, some theoretical planet orbiting about 1.25 AU from Alpha Centauri A ( so that the star appears roughly as bright as the Sun viewed from the Earth ) would see Alpha Centauri B orbit the entire sky once roughly every one year and three months ( or 1.3 ( 4 ) a ), the planet 's own orbital period. Added to this would be the changing apparent position of Alpha Centauri B during its long eighty - year elliptical orbit with respect to Alpha Centauri A. ( The average speed, at 4.5 degrees per Earth year, is comparable in speed to Uranus here. With the eccentricity of the orbit, the maximum speed near periapse, about 18 degrees per Earth year, is faster than Saturn, but slower than Jupiter. The minimum speed near apoapse, about 1.8 degrees per Earth year, is slower than Neptune. ) Depending on its and the planet 's position on their respective orbits, Alpha Centauri B would vary in apparent magnitude between − 18.2 ( dimmest ) and − 21.0 ( brightest ). These visual apparent magnitudes are much dimmer than the apparent magnitude of the Sun as viewed from the Earth ( − 26.7 ). The difference of 5.7 to 8.6 magnitudes means Alpha Centauri B would appear, on a linear scale, 2500 to 190 times dimmer than Alpha Centauri A ( or the Sun viewed from the Earth ), but also 190 to 2500 times brighter than the full Moon as seen from the Earth ( − 12.5 ). Also, if another similar planet orbited at 0.71 AU from Alpha Centauri B ( so that in turn Alpha Centauri B appeared as bright as the Sun seen from the Earth ), this hypothetical planet would receive slightly more light from the more luminous Alpha Centauri A, which would shine 4.7 to 7.3 magnitudes dimmer than Alpha Centauri B ( or the Sun seen from the Earth ), ranging in apparent magnitude between − 19.4 ( dimmest ) and − 22.1 ( brightest ). Thus Alpha Centauri A would appear between 830 and 70 times dimmer than the Sun but some 580 to 6900 times brighter than the full Moon. During the orbital period of such a planet of 0.6 ( 3 ) a, an observer on the planet would see this intensely bright companion star circle the sky just as humans see with the Solar System 's planets. Furthermore, Alpha Centauri A 's sidereal period of approximately eighty years means that this star would move through the local ecliptic as slowly as Uranus with its eighty - four year period, but as the orbit of Alpha Centauri A is more elliptical, its apparent magnitude will be far more variable. Although intensely bright to the eye, the overall illumination would not significantly affect climate nor influence normal plant photosynthesis. An observer on the hypothetical planet would notice a change in orientation to very - long - baseline interferometry reference points commensurate with the binary orbit periodicity plus or minus any local effects such as precession or nutation. Assuming this hypothetical planet had a low orbital inclination with respect to the mutual orbit of Alpha Centauri A and B, then the secondary star would start beside the primary at `` stellar '' conjunction. Half the period later, at `` stellar '' opposition, both stars would be opposite each other in the sky. As a net result, both the local sun and the other star would each be in the sky for half a day, like Sun and Moon are both above the horizon for half a day. But during stellar conjunction, the other star being `` new '' would be in the sky during daytime, while during the opposition, the other star being `` full '' would be in the sky for the whole night. In an Earth - like atmosphere, the light of the other star would be appreciably scattered, causing the sky to be perceptibly blue though darker than during daytime, like during twilight or total solar eclipse. Humans could easily walk around and clearly see the surrounding terrain, and reading a book would be quite possible without any artificial light. Over the following half period, the secondary star would be in the sky for a progressively decreasing part of the night ( and an increasing part of the day ) until at the next conjunction the secondary star would only be in the sky during daytime near the primary star. From a planet orbiting Alpha Centauri A or B, Proxima Centauri would appear as a fourth to fifth magnitude star, as bright as the faint stars of the constellation of Ursa Minor. Other names In modern literature, Rigil Kent ( also Rigel Kent and variants ; / ˈraɪdʒəl ˈkɛnt / ) and Toliman, were cited as colloquial alternative names of Alpha Centauri. Rigil Kent is short for Rigil Kentaurus, which is sometimes further abbreviated to Rigil or Rigel, though that is ambiguous with Beta Orionis, which is also called Rigel. Although the short form Rigel Kent is often cited as an alternative name, the star system is most widely referred to by its Bayer designation Alpha Centauri. The name Toliman originates with Jacobus Golius ' edition of Al - Farghani 's Compendium ( published posthumously in 1669 ). Tolimân is Golius ' latinization of the Arabic name الظلمان ‎ al - Ẓulmān `` the ostriches '', the name of an asterism of which Alpha Centauri formed the main star. During the 19th century, the northern amateur popularist Elijah H. Burritt used the now - obscure name Bungula, possibly coined from `` β '' and the Latin ungula ( `` hoof '' ). Together, Alpha and Beta Centauri form the `` Southern Pointers '' or `` The Pointers '', as they point towards the Southern Cross, the asterism of the constellation of Crux. In Standard Mandarin Chinese, 南 門 Nán Mén, meaning Southern Gate, refers to an asterism consisting of α Centauri and ε Centauri. Consequently, α Centauri itself is known as 南 門 二 Nán Mén Èr, the Second Star of the Southern Gate. To the Australian aboriginal Boorong people of northwestern Victoria, Alpha and Beta Centauri are Bermbermgle, two brothers noted for their courage and destructiveness, who speared and killed Tchingal `` The Emu '' ( the Coalsack Nebula ). The form in Wotjobaluk is Bram - bram - bult. Exploration The Very Large Telescope and star system Alpha Centauri. See also : 2069 Alpha Centauri mission Alpha Centauri is envisioned as a likely first target for manned or unmanned interstellar exploration. Crossing the huge distance between the Sun and Alpha Centauri using current spacecraft technologies would take several millennia, though the possibility of nuclear pulse propulsion or laser light sail technology, as considered in the Breakthrough Starshot program, could reduce the journey time to a matter of decades. Breakthrough Starshot is a proof - of - concept initiative to send a fleet of ultra-fast light - driven nanocraft to explore the Alpha Centauri system, which could pave the way for a first launch within the next generation. An objective of the mission would be to make a fly - by of, and possibly photograph, any planets that might exist in the system. Proxima Centauri b, announced by the European Southern Observatory ( ESO ) in August 2016, would be a target for the Starshot program. In January 2017, Breakthrough Initiatives and the ESO entered a collaboration to enable and implement a search for habitable planets in the Alpha Centauri system. The agreement involves Breakthrough Initiatives providing funding for an upgrade to the VISIR ( VLT Imager and Spectrometer for mid-Infrared ) instrument on ESO 's Very Large Telescope ( VLT ) in Chile. This upgrade will greatly increase the likelihood of planet detection in the system. Distance Alpha Centauri AB distance estimates Source Parallax, mas Distance, pc Distance, ly Distance, Pm Ref. Henderson ( 1839 ) 7003116000000000000 ♠ 1160 ± 110 6999860000000000000 ♠ 0.86 + 0.09 − 0.07 7000281000000000000 ♠ 2.81 + 0.29 − 0.24 7001266000000000000 ♠ 26.6 + 2.8 − 2.3 Henderson ( 1842 ) 7002912800000000000 ♠ 912.8 ± 64 7000110000000000000 ♠ 1.10 + 0.08 − 0.07 7000357000000000000 ♠ 3.57 + 0.27 − 0.23 7001338000000000000 ♠ 33.8 + 2.5 − 2.2 Maclear ( 1851 ) 7002918700000000000 ♠ 918.7 ± 34 7000109000000000000 ♠ 1.09 ± 0.04 7000355000000000000 ♠ 3.55 + 0.14 − 0.13 7001336000000000000 ♠ 33.6 + 1.3 − 1.2 Moesta ( 1868 ) 7002880000000000000 ♠ 880 ± 68 7000113999999999999 ♠ 1.14 + 0.10 − 0.08 7000371000000000000 ♠ 3.71 + 0.31 − 0.27 7001351000000000000 ♠ 35.1 + 2.9 − 2.5 Gill & Elkin ( 1885 ) 7002750000000000000 ♠ 750 ± 10 7000133300000000000 ♠ 1.333 ± 0.018 7000434999999999999 ♠ 4.35 ± 0.06 7001411000000000000 ♠ 41.1 + 0.6 − 0.5 Roberts ( 1895 ) 7002710000000000000 ♠ 710 ± 50 7000141000000000000 ♠ 1.41 + 0.11 − 0.09 7000459000000000000 ♠ 4.59 + 0.35 − 0.30 7001435000000000000 ♠ 43.5 + 3.3 − 2.9 Woolley et al. ( 1970 ) 7002743000000000000 ♠ 743 ± 7 7000134600000000000 ♠ 1.346 ± 0.013 7000438999999999999 ♠ 4.39 ± 0.04 7001415000000000000 ♠ 41.5 ± 0.4 Gliese & Jahreiß ( 1991 ) 7002749000000000000 ♠ 749.0 ± 4.7 7000133500000000000 ♠ 1.335 ± 0.008 7000435500000000000 ♠ 4.355 ± 0.027 7001412000000000000 ♠ 41.20 ± 0.26 van Altena et al. ( 1995 ) 7002749900000000000 ♠ 749.9 ± 5.4 7000133400000000000 ♠ 1.334 ± 0.010 7000434900000000000 ♠ 4.349 + 0.032 − 0.031 7001411500000000000 ♠ 41.15 + 0.30 − 0.29 Perryman et al. ( 1997 ) ( A and B) 7002742120000000000 ♠ 742.12 ± 1.40 7000134749999999999 ♠ 1.3475 ± 0.0025 7000439499999999999 ♠ 4.395 ± 0.008 7001415800000000000 ♠ 41.58 ± 0.08 Söderhjelm ( 1999 ) 7002747100000000000 ♠ 747.1 ± 1.2 7000133850000000000 ♠ 1.3385 + 0.0022 − 0.0021 7000436599999999999 ♠ 4.366 ± 0.007 7001413000000000000 ♠ 41.30 ± 0.07 van Leeuwen ( 2007 ) ( A ) 7002754810000000000 ♠ 754.81 ± 4.11 7000132500000000000 ♠ 1.325 ± 0.007 7000432100000000000 ♠ 4.321 + 0.024 − 0.023 7001408800000000000 ♠ 40.88 ± 0.22 van Leeuwen ( 2007 ) ( B ) 7002796920000000000 ♠ 796.92 ± 25.90 7000125000000000000 ♠ 1.25 ± 0.04 7000409000000000000 ♠ 4.09 + 0.14 − 0.13 7001387000000000000 ♠ 38.7 + 1.3 − 1.2 RECONS TOP100 ( 2012 ) 7002747230000000000 ♠ 747.23 ± 1.17 7000133830000000000 ♠ 1.3383 ± 0.0021 7000436500000000000 ♠ 4.365 ± 0.007 7001412900000000000 ♠ 41.29 ± 0.06 See also Alpha Centauri in fiction List of nearest stars and brown dwarfs Project Longshot Notes Jump up ^ The coordinates of the Sun would be diametrically opposite Alpha Centauri AB, at α = 02 39 36.4951, δ = + 60 ° 50 ′ 02.308 '' Jump up ^ Spellings include Rigjl Kentaurus, Hyde T., `` Ulugh Beighi Tabulae Stellarum Fixarum '', Tabulae Long. ac Lat. Stellarum Fixarum ex Observatione Ulugh Beighi, Oxford, 1665, p. 142., Hyde T., `` In Ulugh Beighi Tabulae Stellarum Fixarum Commentarii '', op. cit., p. 67., Portuguese Riguel Kentaurus da Silva Oliveira, R., `` Crux Australis : o Cruzeiro do Sul '', Artigos : Planetario Movel Inflavel AsterDomus. Jump up ^ Weighted parallax based on parallaxes from van Altena et al. ( 1995 ) and Söderhjelm ( 1999 ). References ^ Jump up to : Van Leeuwen, F. ( 2007 ). `` Validation of the new Hipparcos reduction ''. Astronomy and Astrophysics. 474 ( 2 ) : 653. arXiv : 0708.1752. Bibcode : 2007A&A... 474... 653V. doi : 10.1051 / 0004 - 6361 : 20078357. ^ Jump up to : Ducati, J.R. ( 2002 ). `` VizieR Online Data Catalog : Catalogue of Stellar Photometry in Johnson 's 11 - color system ''. CDS / ADC Collection of Electronic Catalogues. 2237 : 0. Bibcode : 2002yCat. 2237... 0D. ^ Jump up to : Torres, C.A.O. ; Quast, G.R. ; da Silva, L. ; de la Reza, R. ; Melo, C.H.F. ; Sterzik, M. ( 2006 ). `` Search for associations containing young stars ( SACY ) ''. Astronomy and Astrophysics. 460 ( 3 ) : 695 -- 708. arXiv : astro - ph / 0609258. Bibcode : 2006A&A... 460... 695T. doi : 10.1051 / 0004 - 6361 : 20065602. ISSN 0004 - 6361. ^ Jump up to : Valenti, Jeff A. ; Fischer, Debra A. ( 2005 ). `` Spectroscopic Properties of Cool Stars ( SPOCS ). I. 1040 F, G, and K Dwarfs from Keck, Lick, and AAT Planet Search Programs ''. The Astrophysical Journal Supplement Series. 159 ( 1 ) : 141 -- 166. Bibcode : 2005ApJS... 159... 141V. doi : 10.1086 / 430500. ISSN 0067 - 0049. ^ Jump up to : Wilkinson, John ( 2012 ). `` The Sun and Stars ''. New Eyes on the Sun. Astronomers ' Universe. pp. 219 -- 236. doi : 10.1007 / 978 - 3 - 642 - 22839 - 1_10. ISBN 978 - 3 - 642 - 22838 - 4. ISSN 1614 - 659X. ^ Jump up to : P.A. Wiegert ; M.J. Holman ( 1997 ). `` The stability of planets in the Alpha Centauri system ''. The Astronomical Journal. 113 : 1445 -- 1450. arXiv : astro - ph / 9609106. Bibcode : 1997AJ... 113.1445 W. doi : 10.1086 / 118360. ^ Jump up to : Thévenin, F. ; Provost, J. ; Morel, P. ; Berthomieu, G. ; Bouchy, F. ; Carrier, F. ( 2002 ). `` Asteroseismology and calibration of alpha Cen binary system ''. Astronomy & Astrophysics. 392 : L9. arXiv : astro - ph / 0206283. Bibcode : 2002A&A... 392L... 9T. doi : 10.1051 / 0004 - 6361 : 20021074. ^ Jump up to : Kervella, P. ; Bigot, L. ; Gallenne, A. ; Thévenin, F. ( January 2017 ). `` The radii and limb darkenings of α Centauri A and B. Interferometric measurements with VLTI / PIONIER ''. Astronomy & Astrophysics. 597. A137. arXiv : 1610.06185. Bibcode : 2017A&A... 597A. 137K. doi : 10.1051 / 0004 - 6361 / 201629505. ^ Jump up to : Gilli G. ; Israelian G. ; Ecuvillon A. ; Santos N.C. ; Mayor M. ( 2006 ). `` Abundances of Refractory Elements in the Atmospheres of Stars with Extrasolar Planets ''. Astronomy and Astrophysics. 449 ( 2 ) : 723 -- 36. arXiv : astro - ph / 0512219. Bibcode : 2006A&A... 449... 723G. doi : 10.1051 / 0004 - 6361 : 20053850. libcode 2005astro. ph. 12219G. ^ Jump up to : Kervella, P. ; Thévenin, F. ; Ségransan, D. ; Berthomieu, G. ; Lopez, B. ; Morel, P. ; Provost, J. ( 2003 ). `` The diameters of α Centauri A and B ''. Astronomy and Astrophysics. 404 ( 3 ) : 1087 -- 1097. arXiv : astro - ph / 0303634. Bibcode : 2003A&A... 404.1087 K. doi : 10.1051 / 0004 - 6361 : 20030570. ISSN 0004 - 6361. ^ Jump up to : E.E. Mamajek ; L.A. Hillenbrand ( 2008 ). `` Improved Age Estimation for Solar - Type Dwarfs Using Activity - Rotation Diagnostics ''. Astrophysical Journal. 687 ( 2 ) : 1264 -- 1293. arXiv : 0807.1686. Bibcode : 2008ApJ... 687.1264 M. doi : 10.1086 / 591785. ^ Jump up to : Pourbaix, D. ; et al. ( 2002 ). `` Constraining the difference in convective blueshift between the components of alpha Centauri with precise radial velocities ''. Astronomy and Astrophysics. 386 ( 1 ) : 280 -- 85. arXiv : astro - ph / 0202400. Bibcode : 2002A&A... 386... 280P. doi : 10.1051 / 0004 - 6361 : 20020287. ^ Jump up to : `` Naming Stars ''. IAU.org. Retrieved 16 December 2017. Jump up ^ Kervella, Pierre ; Thevenin, Frederic ( 15 March 2003 ). `` A Family Portrait of the Alpha Centauri System ''. European Southern Observatory. eso0307, PR 05 / 03. ^ Jump up to : Hartkopf, W. ; Mason, D.M. ( 2008 ). `` Sixth Catalog of Orbits of Visual Binaries ''. U.S. Naval Observatory. ^ Jump up to : Kervella, P. ; Thévenin, F. ; Lovis, C. ( January 2017 ). `` Proxima 's orbit around α Centauri ''. Astronomy & Astrophysics. 598. L7. arXiv : 1611.03495. Bibcode : 2017A&A... 598L... 7K. doi : 10.1051 / 0004 - 6361 / 201629930. ^ Jump up to : Kunitzsch P., & Smart, T., A Dictionary of Modern star Names : A Short Guide to 254 Star Names and Their Derivations, Cambridge, Sky Pub. Corp., 2006, p. 27 Jump up ^ Davis, George R., Jr. ( October 1944 ). `` The pronunciations, derivations, and meanings of a selected list of star names ''. Popular Astronomy. 52 ( 3 ) : 16. Bibcode : 1944PA... 52... 8D. Jump up ^ Innes, R.T.A. ( October 1915 ). `` A Faint Star of Large Proper Motion ''. Circular of the Union Observatory Johannesburg. 30 : 235 -- 236. Bibcode : 1915CiUO... 30... 235I. Jump up ^ Alden, Harold L. ( 1928 ). `` Alpha and Proxima Centauri ''. Astronomical Journal. 39 ( 913 ) : 20 -- 23. Bibcode : 1928AJ... 39... 20A. doi : 10.1086 / 104871. Jump up ^ Innes, R.T.A. ( September 1917 ). `` Parallax of the Faint Proper Motion Star Near Alpha of Centaurus. 1900. R.A. 14 h 22m 55s. - 0s 6t. Dec - 62 ° 15'2 0'8 t ''. Circular of the Union Observatory Johannesburg. 40 : 331 -- 336. Bibcode : 1917CiUO... 40... 331I. Jump up ^ Stevenson, Angus, ed. ( 2010 ), Oxford Dictionary of English, OUP Oxford, p. 1431, ISBN 0 - 19 - 957112 - 0. Jump up ^ IAU Working Group on Star Names ( WGSN ), International Astronomical Union, retrieved 22 May 2016. Jump up ^ `` Bulletin of the IAU Working Group on Star Names, No. 2 '' ( PDF ). Retrieved 12 October 2016. ^ Jump up to : Heintz, W.D. ( 1978 ). Double Stars. D. Reidel. p. 19. ISBN 90 - 277 - 0885 - 1. Jump up ^ Worley, C.E. ; Douglass, G.G. ( 1996 ). Washington Visual Double Star Catalog, 1996.0 ( WDS ). United States Naval Observatory. Archived from the original on 22 April 2000. Jump up ^ Bazot, M. ; Bourguignon, S. ; Christensen - Dalsgaard, J. ( 2012 ). `` A Bayesian approach to the modelling of alpha Cen A ''. MNRAS. 427 ( 3 ) : 1847 -- 1866. arXiv : 1209.0222. Bibcode : 2012MNRAS. 427.1847 B. doi : 10.1111 / j. 1365 - 2966.2012. 21818. x. Jump up ^ Miglio, A. ; Montalbán, J. ( 2005 ). `` Constraining fundamental stellar parameters using seismology. Application to α Centauri AB ''. Astronomy & Astrophysics. 441 ( 2 ) : 615 -- 629. arXiv : astro - ph / 0505537. Bibcode : 2005A&A... 441... 615M. doi : 10.1051 / 0004 - 6361 : 20052988. Jump up ^ Thoul, A. ; Scuflaire, R. ; Noels, A. ; Vatovez, B. ; Briquet, M. ; Dupret, M. - A. ; Montalban, J. ( 2003 ). `` A New Seismic Analysis of Alpha Centauri ''. Astronomy & Astrophysics. 402 : 293 -- 297. arXiv : astro - ph / 0303467. Bibcode : 2003A&A... 402... 293T. doi : 10.1051 / 0004 - 6361 : 20030244. Jump up ^ Eggenberger, P. ; Charbonnel, C. ; Talon, S. ; Meynet, G. ; Maeder, A. ; Carrier, F. ; Bourban, G. ( 2004 ). `` Analysis of α Centauri AB including seismic constraints ''. Astronomy & Astrophysics. 417 : 235 -- 246. arXiv : astro - ph / 0401606. Bibcode : 2004A&A... 417... 235E. doi : 10.1051 / 0004 - 6361 : 20034203. ^ Jump up to : `` The Colour of Stars ''. Australia Telescope, Outreach and Education. Commonwealth Scientific and Industrial Research Organisation. 21 December 2004. Archived from the original on 10 March 2012. Retrieved 16 January 2012. Jump up ^ Bazot, M. ; et al. ( 2007 ). `` Asteroseismology of α Centauri A. Evidence of rotational splitting ''. Astronomy and Astrophysics. 470 ( 1 ) : 295 -- 302. arXiv : 0706.1682. Bibcode : 2007A&A... 470... 295B. doi : 10.1051 / 0004 - 6361 : 20065694. Jump up ^ Guinan, E. ; Messina, S. ( 1995 ). `` IAU Circular 6259, Alpha Centauri B ''. Central Bureau for Astronomical Telegrams. ^ Jump up to : Robrade, J. ; Schmitt, J.H.M.M. ; Favata, F. ( 2005 ). `` X-rays from α Centauri -- The darkening of the solar twin ''. Astronomy and Astrophysics. 442 ( 1 ) : 315 -- 321. arXiv : astro - ph / 0508260. Bibcode : 2005A&A... 442... 315R. doi : 10.1051 / 0004 - 6361 : 20053314. Jump up ^ Van Zyl, Johannes Ebenhaezer ( 1996 ). Unveiling the Universe : An Introduction to Astronomy. Springer. ISBN 3 - 540 - 76023 - 7. ^ Jump up to : Hartung, E.J. ; Frew, David ; Malin, David ( 1994 ). `` Astronomical Objects for Southern Telescopes ''. Cambridge University Press. ^ Jump up to : Norton, A.P. ; Ed. I. Ridpath ( 1986 ). Norton 's 2000.0 : Star Atlas and Reference Handbook. Longman Scientific and Technical. pp. 39 -- 40. Jump up ^ Mitton, Jacquelin ( 1993 ). The Penguin Dictionary of Astronomy. Penguin Books. p. 148. Jump up ^ `` Our Nearest Star System Observed Live ''. Retrieved 27 January 2016. Jump up ^ This is calculated for a fixed latitude by knowing the star 's declination ( δ ) using the formulae ( 90 ° + δ ). Alpha Centauri 's declination is − 60 ° 50 ′, so the observed latitude where the star is circumpolar will be south of − 29 ° 10 ′ S or 29 °. Similarly, the place where Alpha Centauri never rises for northern observers is north of the latitude ( 90 ° + δ ) N or + 29 ° N. Jump up ^ James, Andrew. `` ' The ' '' Constellations : Part 2 Culmination Times `` ' ''. Sydney, New South Wales : Southern Astronomical Delights. Retrieved 6 August 2008. ^ Jump up to : Matthews, R.A.J. ; Gilmore, Gerard ( 1993 ). `` Is Proxima really in orbit about α Cen A / B ? ''. Monthly Notices of the Royal Astronomical Society. 261 : L5. Bibcode : 1993MNRAS. 261L... 5M. doi : 10.1093 / mnras / 261.1. l5. Jump up ^ Benedict, G. Fritz ; et al. ( 1998 ). Donahue, R.A. ; Bookbinder, J.A., eds. Proxima Centauri : Time - resolved Astrometry of a Flare Site using HST Fine Guidance Sensor 3. ASP Conf. Ser. 154, The Tenth Cambridge Workshop on Cool Stars, Stellar Systems and the Sun. p. 1212. Bibcode : 1998ASPC... 154.1212 B. Jump up ^ Page, A.A. ( 1982 ). `` Mount Tamborine Observatory ''. International Amateur - Professional Photoelectric Photometry Communication. 10 : 26. Bibcode : 1982IAPPP... 10... 26P. Jump up ^ `` Light Curve Generator ( LCG ) - aavso.org ''. www.aavso.org. Retrieved 7 June 2017. Jump up ^ Ptolemaeus, Claudius ( 1984 ). Ptolemy 's Almagest ( PDF ). Translated by Toomer, G.J. London : Gerald Duckworth & Co. p. 368, note 136. ISBN 0 - 7156 - 1588 - 2. Jump up ^ Knobel, p. 416. Jump up ^ Kameswara Rao, R. ( 1984 ). `` Father J. Richaud and early telescope observations in India ''. Bulletin of the Astronomical Society of India. 81 : 81. Jump up ^ Glass, I.S. ( 2013 ). Nicolas - Louis de La Caille, Astronomer and Geodesist. Oxford University Press. ^ Jump up to : Pannekoek, Anton ( 1989 ) ( 1961 ). A History of Astronomy. Dover. pp. 345 -- 346. ISBN 0 - 486 - 65994 - 1. Jump up ^ Herschel, J.F.W. ( 1847 ). Results of Astronomical Observations made during the years 1834, 5, 6, 7, 8 at the Cape of Good Hope ; being the completion of a telescopic survey of the whole surface of the visible heavens, commenced in 1825. Smith, Elder and Co, London. ^ Jump up to : Kamper, K.W. ; Wesselink, A.J. ( 1978 ). `` Alpha and Proxima Centauri ''. Astronomical Journal. 83 : 1653. Bibcode : 1978AJ... 83.1653 K. doi : 10.1086 / 112378. Jump up ^ `` Best image of Alpha Centauri A and B ''. www.spacetelescope.org. Retrieved 29 August 2016. Jump up ^ Aitken, R.G. ( 1961 ). The Binary Stars. Dover. pp. 236 -- 237. Jump up ^ `` Sixth Catalogue of Orbits of Visual Binary Stars : Ephemeris ( 2008 ) ''. U.S. Naval Observatory. Retrieved 13 August 2008. Jump up ^ Boffin, Henri M.J. ; et al. ( 4 December 2013 ). `` Possible astrometric discovery of a substellar companion to the closest binary brown dwarf system WISE J104915. 57 -- 531906.1 ''. Astronomy and Astrophysics. 561 : L4. arXiv : 1312.1303. Bibcode : 2014A&A... 561L... 4B. doi : 10.1051 / 0004 - 6361 / 201322975. Jump up ^ `` The Hipparcos Catalogue -- R.A. 14h - 19h, HIP : 68301 - 93276 '' ( PDF ). ESA. Retrieved 6 August 2008. Jump up ^ `` Hipparcos Data Vol. 8. ( 1997 ) ''. ESA. Archived from the original on 24 December 2009. Retrieved 1 August 2008. Jump up ^ `` The 150 Stars in the Hipparcos Catalogue Closest to the Sun ''. ESA. 1997. Retrieved 6 August 2008. Jump up ^ `` Contents of the Hipparcos Catalogue ( 1997 ) '' ( PDF ). ESA. Retrieved 6 August 2008. Jump up ^ Benedict, G.F. ; et al. ( 1999 ). `` Interferometric Astrometry of Proxima Centauri and Barnard 's Star Using HUBBLE SPACE TELESCOPE Fine Guidance Sensor 3 : Detection Limits for Substellar Companions ''. Astronomical Journal. 118 ( 2 ) : 1086 -- 1100. arXiv : astro - ph / 9905318. Bibcode : 1999AJ... 118.1086 B. doi : 10.1086 / 300975., ^ Jump up to : Aitken, R.G. ( 1961 ). The Binary Stars. Dover. p. 236. Jump up ^ ( ( 11.2 + 35.6 ) / 2 ) 3 / 79.91 2 = 2.0 ( displaystyle ( \begin ( smallmatrix ) ( ( 11.2 + 35.6 ) / 2 ) ^ ( 3 ) / 79.91 ^ ( 2 ) = 2.0 end ( smallmatrix ) ) ), see formula ^ Jump up to : Kim, Y-C. J. ( 1999 ). `` Standard Stellar Models ; alpha Cen A and B ''. Journal of the Korean Astronomical Society. 32 : 119. Bibcode : 1999JKAS... 32... 119K. ^ Jump up to : `` The One Hundred Nearest Star Systems ''. Research Consortium On Nearby Stars. Georgia State University. 7 September 2007. Archived from the original on 12 November 2007. Retrieved 2 December 2014. Jump up ^ Andrew James ( 11 March 2008 ). `` ALPHA CENTAURI : 6 ''. Homepage.mac.com. Retrieved 12 August 2010. ^ Jump up to : Aitken, R.G. ( 1961 ). The Binary Stars. Dover. p. 235. Jump up ^ Ségransan, D. ; Kervella, P. ; Forveille, T. ; Queloz, D. ( 2003 ). `` First radius measurements of very low mass stars with the VLTI ''. Astronomy and Astrophysics Letters. 397 ( 3 ) : L5 -- L8. arXiv : astro - ph / 0211647. Bibcode : 2003A&A... 397L... 5S. doi : 10.1051 / 0004 - 6361 : 20021714. Jump up ^ Clavin, Whitney ; Harrington, J.D. ( 25 April 2014 ). `` NASA 's Spitzer and WISE Telescopes Find Close, Cold Neighbor of Sun ''. NASA. Archived from the original on 26 April 2014. Retrieved 25 April 2014. Jump up ^ ESA : Hipparcos Site. `` High - Proper Motion Stars ( 2004 ) ''. Jump up ^ Aristotle. `` De Caelo ( On the Heavens ) : Book II. Part 11. ( 2004 ) ''. Jump up ^ Berry, A., `` A History of Astronomy '', Dover, 1989, pp. 357 -- 358 Jump up ^ Pannekoek, A., `` A Short History of Astronomy '', Dover, 1989 Jump up ^ Holberg, J.B. ( 2007 ). Sirius : Brightest Diamond in the Night Sky. Praxis Publishing. pp. 41 -- 42. ISBN 0 - 387 - 48941 - X. Jump up ^ Tung, Brian. `` Star Catalogue of Ptolemy ''. The Astronomy Corner : Reference ( 2006 ). Archived from the original on 15 November 2007. Jump up ^ Newton R.R., `` The Crime of Claudius Ptolemy '', T. Baltimore : Johns Hopkins University Press, ( 1977 ) Jump up ^ Pannekoek, A., `` A Short History of Astronomy '', Dover, 1989, p. 157 Jump up ^ Grasshoff, G. ( 1990 ). The History of Ptolemy 's Star Catalogue. Springer. pp. 319 -- 394. ISBN 0 - 387 - 97181 - 5. ^ Jump up to : Henderson, H. ( 1839 ). `` On the parallax of α Centauri ''. Monthly Notices of the Royal Astronomical Society. 4 ( 19 ) : 168 -- 169. Bibcode : 1839MNRAS... 4... 168H. doi : 10.1093 / mnras / 4.19. 168. Jump up ^ Astronomical Society of South Africa. `` Henderson, Thomas ( FRS ) ( 2008 ) ''. Archived from the original on 9 September 2012. Jump up ^ Pannekoek, A., `` A Short History of Astronomy '', Dover, 1989, p. 333 Jump up ^ Maclear, M. ( 1851 ). `` Determination of Parallax of α and α Centauri ''. Astronomische Nachrichten. 32 ( 16 ) : 243 -- 244. Bibcode : 1851MNRAS... 11... 131M. doi : 10.1002 / asna. 18510321606. Jump up ^ N.L., de La Caillé ( 1976 ). Travels at the Cape, 1751 -- 1753 : an annotated translation of Journal historique du voyage fait au Cap de Bonne - Espérance. Translated by Raven - Hart, R. Cape Town. ISBN 0 - 86961 - 068 - 6. ^ Jump up to : Kervella, Pierre ; et al. ( Oct 19, 2016 ). `` Close stellar conjunctions of α Centauri A and B until 2050 An m = 7.8 star may enter the Einstein ring of α Cen A ''. arXiv : 1610.06079. Jump up ^ Proper motions are expressed in smaller angular units than arcsec, being measured in milli - arcsec ( mas. ) or one - thousandth of an arcsec. Negative values for proper motion in RA indicate the sky motion is from east to west, and in declination north to south. Jump up ^ van den Bos W.H. ( 1926 ). `` A Table of Orbits of Visual Binary Stars ( aka. First Orbit Catalogue of Binary Stars ) ''. Bulletin of the Astronomical Institutes of the Netherlands. 3 : 149. Bibcode : 1926BAN... 3... 149V. Jump up ^ van den Bos W.H. ( 1926 ). `` Table of Visual Binary Stars ''. Union Observatory Circular. 2 : 356. Jump up ^ Changes in position angle ( θ ) are calculated as ; θ − θ = μ × sin α × ( t − t ), where ; α = right ascension ( in degrees ), μ is the common proper motion ( cpm. ) expressed in degrees, and θ and θ are the current position angle and calculated position angle at the different epochs. ^ Jump up to : Matthews, R.A.J. ( 1994 ). `` The Close Approach of Stars in the Solar Neighbourhood ''. Quarterly Journal of the Royal Astronomical Society. 35 : 1 -- 8. Bibcode : 1994QJRAS... 35... 1M. Jump up ^ C.A.l., Bailer - Jones ( 2015 ). `` Close encounters of the stellar kind ''. Astronomy and Astrophysics. 575 : A35 -- A48. arXiv : 1412.3648. Bibcode : 2015A&A... 575A... 35B. doi : 10.1051 / 0004 - 6361 / 201425221. Jump up ^ Sky and Telescope, April 1998 ( p60 ), based on computations from HIPPARCOS data. Jump up ^ Jean Meeus ( 2002 ). More Mathematical Astronomy Morsels. p. 347. ISBN 0 - 943396 - 74 - 3. ^ Jump up to : Hartung, E.J. ; Frew, D. ; Malin, D. ( 1994 ). Astronomical Objects for Southern Telescopes. Melbourne University Press. p. 194. ISBN 0 - 522 - 84553 - 3. ^ Jump up to : Anglada - Escude G, Amado PJ, Barnes J, Berdinas ZM, Butler RP, Coleman GA, Cueva I, Dreizler S, Endl M, Giesers B, Jeffers SV, Jenkins JS, Jones HR, Kiraga M, Kürster M, López - González MJ, Marvin CJ, Morales N, Morin J, Nelson RP, Ortiz JL, Ofir A, Paardekooper SJ, Reiners A, Sarmiento LF, Rodríguez E, Rodríguez - Lopez C, Strachan JP, Tsapras Y, Tuomi M, Zechmeister M ( 13 July 2016 ). `` A terrestrial planet candidate in a temperate orbit around Proxima Centauri '' ( PDF ). European Southern Observatory. Retrieved 26 August 2016. Jump up ^ Singal, Ashok K. ( 2014 ). `` Life on a tidally - locked planet ''. Planex Newsletter. 4 ( 2 ) : 8. arXiv : 1405.1025. Bibcode : 2014arXiv1405. 1025S. Jump up ^ It Turns Out the Closest Exoplanet to Us Does n't Actually Exist Jump up ^ Poof ! The Planet Closest To Our Solar System Just Vanished Jump up ^ Rajpaul, Vinesh ; Aigrain, Suzanne ; Roberts, Stephen J. ( 19 October 2015 ), `` Ghost in the time series : no planet for Alpha Cen B '', Monthly Notices of the Royal Astronomical Society, 456 : L6, arXiv : 1510.05598, Bibcode : 2016MNRAS. 456L... 6R, doi : 10.1093 / mnrasl / slv164. Jump up ^ LaPage, Andrew ( 28 March 2015 ). `` Has Another Planet Been Found Orbiting Alpha Centauri B ? ''. Drew ex Machina. Retrieved 5 September 2015. Jump up ^ Demory, Brice - Olivier ; et al. ( June 2015 ). `` Hubble Space Telescope search for the transit of the Earth - mass exoplanet Alpha Centauri Bb ''. Monthly Notices of the Royal Astronomical Society. 450 ( 2 ) : 2043 -- 2051. arXiv : 1503.07528. Bibcode : 2015MNRAS. 450.2043 D. doi : 10.1093 / mnras / stv673. Jump up ^ Demory, Brice - Olivier ; Ehrenreich, David ; Queloz, Didier ; Seager, Sara ; Gilliland, Ronald ; Chaplin, William J. ; Proffitt, Charles ; Gillon, Michael ; Guenther, Maximilian N. ; Benneke, Bjoern ; Dumusque, Xavier ; Lovis, Christophe ; Pepe, Francesco ; Segransan, Damien ; Triaud, Amaury ; Udry, Stephane ( 25 March 2015 ). `` Hubble Space Telescope search for the transit of the Earth - mass exoplanet Alpha Centauri Bb ''. Monthly Notices of the Royal Astronomical Society. 450 ( 2 ) : 2043. arXiv : 1503.07528 v1. Bibcode : 2015MNRAS. 450.2043 D. doi : 10.1093 / mnras / stv673. Jump up ^ Twin Earths may lurk in our nearest star system ^ Jump up to : `` Why Have n't Planets Been Detected around Alpha Centauri ''. Universe Today. Archived from the original on 21 April 2008. Retrieved 19 April 2008. Jump up ^ Stephens, Tim ( 7 March 2008 ). `` Nearby star should harbor detectable, Earth - like planets ''. News & Events. UC Santa Cruz. Archived from the original on 17 April 2008. Retrieved 19 April 2008. ^ Jump up to : Thebault, P. ; Marzazi, F. ; Scholl, H. ( 2009 ). `` Planet formation in the habitable zone of alpha centauri B ''. Monthly Notices of the Royal Astronomical Society. 393 : L21 -- L25. arXiv : 0811.0673. Bibcode : 2009MNRAS. 393L... 21T. doi : 10.1111 / j. 1745 - 3933.2008. 00590. x. ^ Jump up to : Quintana, E.V. ; Lissauer, J.J. ; Chambers, J.E. ; Duncan, M.J. ( 2002 ). `` Terrestrial Planet Formation in the Alpha Centauri System ''. Astrophysical Journal. 2, part 1 ( 2 ) : 982 -- 996. Bibcode : 2002ApJ... 576... 982Q. CiteSeerX 10.1. 1.528. 4268. doi : 10.1086 / 341808. ^ Jump up to : Guedes, Javiera M. ; Rivera, Eugenio J. ; Davis, Erica ; Laughlin, Gregory ; Quintana, Elisa V. ; Fischer, Debra A. ( 2008 ). `` Formation and Detectability of Terrestrial Planets Around Alpha Centauri B ''. Astrophysical Journal. 679 ( 2 ) : 1582 -- 1587. arXiv : 0802.3482. Bibcode : 2008ApJ... 679.1582 G. doi : 10.1086 / 587799. Jump up ^ Dumusque, X. ; Pepe, F. ; Lovis, C. ; Ségransan, D. ; Sahlmann, J. ; Benz, W. ; Bouchy, F. ; Mayor, M. ; Queloz, D. ; Santos, N. ; Udry, S. ( 17 October 2012 ). `` An Earth mass planet orbiting Alpha Centauri B '' ( PDF ). Nature. 490 ( 7423 ) : 207 -- 11. Bibcode : 2012Natur. 491... 207D. doi : 10.1038 / nature11572. PMID 23075844. Retrieved 17 October 2012. Jump up ^ Billings, Lee. `` Miniature Space Telescope Could Boost the Hunt for `` Earth Proxima '' ( Video ) ``. Scientific American. Jump up ^ Zhao, L. ; Fischer, D. ; Brewer, J. ; Giguere, M. ; Rojas - Ayala, B. ( January 2018 ). `` Planet Detectability in the Alpha Centauri System ''. Astronomical Journal. 155 ( 1 ) : 12. arXiv : 1711.06320. Bibcode : 2018AJ... 155... 24Z. doi : 10.3847 / 1538 - 3881 / aa9bea. Retrieved 29 December 2017. Jump up ^ Javiera Guedes, Terrestrial Planet Formation Around Alpha Cen B Jump up ^ see Lissauer and Quintana in references below Jump up ^ M. Barbieri ; F. Marzari ; H. Scholl ( 2002 ). `` Formation of terrestrial planets in close binary systems : The case of α Centauri A ''. Astronomy & Astrophysics. 396 ( 1 ) : 219 -- 224. arXiv : astro - ph / 0209118. Bibcode : 2002A&A... 396... 219B. doi : 10.1051 / 0004 - 6361 : 20021357. Jump up ^ Lissauer, J.J. ; E.V. Quintana ; J.E. Chambers ; M.J. Duncan & F.C. Adams ( 2004 ). `` Terrestrial Planet Formation in Binary Star Systems ''. Revista Mexicana de Astronomia y Astrofisica ( Serie de Conferencias ). 22 : 99 -- 103. arXiv : 0705.3444. Bibcode : 2004RMxAC... 22... 99L. Jump up ^ Quintana, Elisa V. ; Lissauer, Jack J. ( 2007 ). Haghighipour, Nader, ed. Terrestrial Planet Formation in Binary Star Systems. Planets in Binary Star Systems. Springer. pp. 265 -- 284. ISBN 978 - 90 - 481 - 8687 - 7. ^ Jump up to : Croswell, Ken ( April 1991 ). `` Does Alpha Centauri Have Intelligent Life ? ''. Astronomy. 19 : 28 -- 37. Bibcode : 1991Ast... 19d... 28C. ( Subscription required ( help ) ). Jump up ^ Gilster, Paul ( 5 July 2006 ). `` Proxima Centauri and Habitability ''. Centauri Dreams. Retrieved 12 August 2010. Jump up ^ Cain, Fraser ( 10 March 2008 ). `` If Alpha Centauri Has Earth - like Planets, Can We Detect Them ? ''. Universe Today. Archived from the original on 14 March 2008. Retrieved 10 March 2008. Jump up ^ `` Planet Hunting by Numbers '' ( Press release ). Jet Propulsion Laboratory. 18 October 2006. Retrieved 24 April 2007. Jump up ^ Mullen, Leslie ( 2 June 2011 ). `` Rage Against the Dying of the Light ''. Astrobiology Magazine. Archived from the original on 4 June 2011. Retrieved 7 June 2011. ^ Jump up to : Wiegert, J. ; Liseau, R. ; Thébault, P. ; et al. ( March 2014 ). `` How dusty is α Centauri ? Excess or non-excess over the infrared photospheres of main - sequence stars ''. Astronomy & Astrophysics. 563. A102. arXiv : 1401.6896. Bibcode : 2014A&A... 563A. 102W. doi : 10.1051 / 0004 - 6361 / 201321887. Jump up ^ Computed ; using in solar terms : 1.1 M and 0.92 M, luminosities 1.57 and 0.51 L * / L, Sun magnitude − 26.73 ( v ), 11.2 to 35.6 AU orbit. The minimum luminosity adds the planet 's orbital radius to the A -- B distance ( max ) ( conjunction ). The maximum luminosity subtracts the planet 's orbital radius to the A -- B distance ( min ) ( opposition ). Jump up ^ `` Proxima Centauri UV flux distribution ''. ESA / Laboratory for Space Astrophysics and Theoretical Physics. Retrieved 11 July 2007. Jump up ^ Kaler, Jim. `` Rigil Kentaurus ''. University of Illinois. Retrieved 3 August 2008. Jump up ^ Rees, M. ( ed. ). Universe : The Definitive Visual Guide. London : Dorling Kindersley, 2012. P. 252. Jump up ^ Kaler, J.B. The Hundred Greatest Stars. New York : Copernicus Books, 2002. P. 15. Jump up ^ Schaaf, F. The Brightest Stars : Discovering the Universe through the Sky 's Most Brilliant Stars. Hoboken, NJ : John Wiley & Sons, 2008. P. 122. Jump up ^ Bailey, F., `` The Catalogues of Ptolemy, Ulugh Beigh, Tycho Brahe, Halley, and Hevelius '', Memoirs of Royal Astronomical Society, vol. XIII, London, 1843. Jump up ^ P. Kunitzsch, `` Naturwissenschaft und Philologie : Die arabischen Elemente in der Nomenklatur und Terminologie der Himmelskunde '' Die Sterne 52 ( 1976 ), 218 -- 227 ( p. 223 ). C.f.H. Hermelink, review of Arabische Sternnamen in Europa by Paul Kunitzsch, Journal of the American Oriental Society Vol. 81, No. 3 ( Aug. -- Sep. 1961 ), pp. 309 -- 312. stellam in laevo pede Centauri, qui asterismus Tolimân dicitur J. Golius, Elementa astronomica, arabice et latine. Cum notis ad res exoticas sive orientales, quae in iis occurrunt Amsterdam ( 1669 ), p. 76. A spurious Hebrew etymology introduced by Frances Rolleston, Mazzaroth ; or, The constellations ( 1862 ), p. 17 ( `` the heretofore and hereafter '' ) has found some reflection in astrological literature ( c.f. E.W. Bullinger, The Witness of the Stars ( 1893 ), p. 34 ; Thomas H. Perdue Passover & Sukkot, Forever ( 2011 ), p. 446 ; Mathew James, The Original Prophecy, Dog Ear Publishing ( 2011 ), p. 7 ). Jump up ^ Burritt, E.H., Atlas, Designed to Illustrate the Geography of the Heavens, ( New Edition ), New York, F.J. Huntington and Co., 1835, pl. VII. Jump up ^ ( in Chinese ) ( AEEA ( Activities of Exhibition and Education in Astronomy ) 天文 教育 資訊 網 2006 年 6 月 27 日 ) ^ Jump up to : Hamacher, Duane W. ; Frew, David J. ( 2010 ). `` An Aboriginal Australian Record of the Great Eruption of Eta Carinae ''. Journal of Astronomical History & Heritage. 13 ( 3 ) : 220 -- 234. arXiv : 1010.4610. Bibcode : 2010JAHH... 13... 220H. Jump up ^ Stanbridge, W.M. ( 1857 ). `` On the Astronomy and Mythology of the Aboriginies of Victoria ''. Transactions Philosophical Institute Victoria. 2 : 137 -- 140. ^ Jump up to : `` VLT to Search for Planets in Alpha Centauri System - ESO Signs Agreement with Breakthrough Initiatives ''. European Southern Observatory. 9 January 2017. Retrieved 10 January 2017. Jump up ^ Overbye, Dennis ( 12 April 2016 ). `` A Visionary Project Aims for Alpha Centauri, a Star 4.37 Light - Years Away ''. The New York Times. Retrieved 12 April 2016. Jump up ^ O'Neill, Ian ( 8 July 2008 ). `` How Long Would it Take to Travel to the Nearest Star ? ''. Universe Today. Jump up ^ Domonoske, Camila ( 12 April 2016 ). `` Forget Starships : New Proposal Would Use ' Starchips ' To Visit Alpha Centauri ''. National Public Radio. Retrieved 14 April 2016. ^ Jump up to : `` Starshot ''. Breakthrough Initiatives. Retrieved 10 January 2017. Jump up ^ Overbye, Dennis ( 12 April 2016 ). `` Reaching for the Stars, Across 4.37 Light - Years ''. The New York Times. Retrieved 10 January 2017. Jump up ^ Chang, Kenneth ( 24 August 2016 ). `` One Star Over, a Planet That Might Be Another Earth ''. The New York Times. Retrieved 10 January 2017. Jump up ^ Klesman, Alison ( 9 January 2017 ). `` ESO and the Breakthrough Initiatives team up to search for extrasolar planets next door ''. Astronomy Magazine. Retrieved 10 January 2017. Jump up ^ Henderson, T. ( 1842 ). `` The Parallax of α Centauri, deduced from Mr. Maclear 's Observations at the Cape of Good Hope, in the Years 1839 and 1840 ''. Memoirs of the Royal Astronomical Society. 12 : 370 -- 371. Bibcode : 1842MmRAS... 12... 329H. Jump up ^ Maclear, T. ( 1851 ). `` Determination of the Parallax of α 1 and α2 Centauri, from Observations made at the Royal Observatory, Cape of Good Hope, in the Years 1842 - 3 - 4 and 1848 ''. Memoirs of the Royal Astronomical Society. 20 : 98. Bibcode : 1851MmRAS... 20... 70M. Jump up ^ Moesta, C.G. ( 1868 ). `` Bestimmung der Parallaxe von α und β Centauri '' ( Determining the parallax of α and β Centauri ). Astronomische Nachrichten ( in German ). 71 ( 8 ) : 117 -- 118. Bibcode : 1868AN... 71... 113M. doi : 10.1002 / asna. 18680710802. Jump up ^ Gill, David ; Elkin, W.L. ( 1885 ). `` Heliometer - Determinations of Stellar Parallax in the Southern Hemisphere ''. Memoirs of the Royal Astronomical Society. 48 : 188. Bibcode : 1885MmRAS... 48... 1G. Jump up ^ Roberts, Alex W. ( 1895 ). `` Parallax of α Centauri from Meridian Observations 1879 -- 1881 ''. Astronomische Nachrichten. 139 ( 12 ) : 189 -- 190. Bibcode : 1895AN... 139... 177R. doi : 10.1002 / asna. 18961391202. Jump up ^ Woolley, R. ; Epps, E.A. ; Penston, M.J. ; Pocock, S.B. ( 1970 ). `` Woolley 559 ''. Catalogue of stars within 25 parsecs of the Sun. Royal Greenwich Observatory. 5. Bibcode : 1970ROAn... 5... W. Retrieved 9 May 2014. Jump up ^ Gliese, W. ; Jahreiß, H. ( 1991 ). `` Gl 559 ''. Preliminary Version of the Third Catalogue of Nearby Stars. Astronomische Rechen - Institut. Retrieved 9 May 2014. Jump up ^ Van Altena, W.F. ; Lee, J.T. ; Hoffleit, E.D. ( 1995 ). `` GCTP 3309 ''. The General Catalogue of Trigonometric Stellar Parallaxes ( Fourth ed. ). Yale University Observatory. Retrieved 9 May 2014. Jump up ^ Perryman ; et al. ( 1997 ). `` HIP 71683 ''. The Hipparcos and Tycho Catalogues. Retrieved 9 May 2014. Jump up ^ Perryman ; et al. ( 1997 ). `` HIP 71683 ''. The Hipparcos and Tycho Catalogues. Retrieved 9 May 2014. Jump up ^ Perryman ; et al. ( 1997 ). `` HIP 71681 ''. The Hipparcos and Tycho Catalogues. Retrieved 9 May 2014. Jump up ^ Perryman ; et al. ( 1997 ). `` HIP 71681 ''. The Hipparcos and Tycho Catalogues. Retrieved 9 May 2014. Jump up ^ Söderhjelm, Staffan ( 1999 ). `` HIP 71683 ''. Visual binary orbits and masses post Hipparcos. Retrieved 9 May 2014. Jump up ^ van Leeuwen, Floor ( 2007 ). `` HIP 71683 ''. Validation of the new Hipparcos reduction. Jump up ^ van Leeuwen, Floor ( 2007 ). `` HIP 71681 ''. Validation of the new Hipparcos reduction. External links Wikimedia Commons has media related to Alpha Centauri. SIMBAD observational data Sixth Catalogue of Orbits of Visual Binary Stars U.S.N.O. The Imperial Star -- Alpha Centauri Alpha Centauri -- A Voyage to Alpha Centauri Immediate History of Alpha Centauri eSky : Alpha Centauri Alpha Centauri at Constellation Guide Hypothetical planets or exploration `` A Family Portrait of the Alpha Centauri System ''. SpaceRef.com. Retrieved 21 March 2003. Alpha Centauri System O Sistema Alpha Centauri ( Portuguese ) Alpha Centauri -- Associação de Astronomia ( Portuguese ) Thompson, Andrea ( 7 March 2008 ). `` Nearest Star System Might Harbor Earth Twin ''. SPACE.com. Archived from the original on 2 June 2008. Retrieved 17 July 2008. Coordinates : 14 39 36.4951, − 60 ° 50 ′ 02.308 '' The Alpha Centauri system Stars Alpha Centauri A Alpha Centauri B Proxima Centauri Planets Alpha Centauri Bb Alpha Centauri Bc Proxima Centauri b Proposed missions concepts 2069 Alpha Centauri mission AIMStar Breakthrough Starshot Project Longshot Starlight = This planet 's existence was disproven Celestial objects within 0 -- 5 light - years → Primary member type Celestial objects by systems. Secondary members are listed in small print. Main - sequence stars G - type Sun ( 0 ly ) rest of Solar System α Cen ( 4.366 ± 0.007 ly ) K - type main - sequence star B red dwarf C ( Proxima Centauri ) ( 4.2430 ± 0.0017 ly ) planet b Italic are systems without known trigonometric parallax. Centaurus constellation Stars ( list ) Bayer α ( Rigil Kentaurus ) β ( Hadar ) γ δ ε ζ η θ ( Menkent ) ι ( Alkhaim ) κ λ μ ν ξ ξ ο ο π ρ σ τ υ υ φ χ ψ Flamsteed 1 ( i ) 2 ( g ) 3 ( k ) 4 ( h ) Variable V Y RR RU RV SV SX SZ UW UY XX AZ BB BH BK BV DY KK V346 V436 V442 V485 V553 V636 V716 V743 V744 V752 V757 V761 ( a ) V763 ( C ) V765 V766 V767 V768 V788 V789 V790 V795 V801 V803 V808 V809 V810 V815 V816 ( Przybylski 's Star ) V817 V821 V823 V824 V827 V828 V831 V834 V836 V838 V841 V842 V854 V857 V863 V869 V871 V883 V885 V914 V918 V928 V945 ( H ) V947 V961 V964 V992 V1019 V1025 V1051 V1052 V1154 HR 4318 4321 4350 4353 4354 4360 4364 4370 4372 4393 4396 4398 4403 4409 4411 4413 4415 4417 4423 4447 4453 4460 ( A ) 4462 4466 ( C ) 4470 4472 4475 4476 ( C ) 4487 4499 4502 4508 4513 4516 4519 4522 4523 4524 4537 ( j ) 4541 4546 ( B ) 4551 4556 4557 4563 4568 4570 4582 4600 4620 ( E ) 4631 4637 4648 4652 ( D ) 4658 4675 4682 ( F ) 4712 ( x ) 4713 4714 4718 4721 4724 ( x ) 4732 ( G ) 4734 4748 ( u ) 4782 4788 4794 4796 4817 ( l ) 4818 4831 ( w ) 4836 4838 4850 4871 4872 4874 ( p ) 4879 4880 4882 4885 4888 ( e ) 4889 ( n ) 4903 4906 4922 4940 ( f ) 4941 4944 4947 4951 4970 4972 4973 4979 4980 4982 4985 4988 4989 4991 4996 4999 5006 ( r ) 5008 5016 5024 5027 5029 5035 ( J ) 5036 5038 5039 5041 ( m ) 5043 5046 5048 5058 5060 5061 5063 5065 5071 ( K ) 5089 ( d ) 5092 5103 5104 5113 5117 5118 5121 5122 5124 5130 5136 5140 5141 ( Q ) 5151 5152 5155 5157 5172 ( M ) 5174 ( z ) 5175 5176 5198 5206 5207 ( N ) 5208 5212 5217 5222 ( y ) 5224 5230 5234 5236 5239 5241 5251 5252 5259 5266 5268 5281 5286 5289 5294 5297 5308 5318 5319 5325 5349 5357 5358 ( v ) 5371 5376 5398 5400 5403 5417 5419 5428 5432 5439 5446 5449 5456 5461 5466 5471 ( b ) 5474 5485 ( c ) 5489 ( c ) 5508 5542 5549 5558 5561 5562 5572 5579 5585 5587 HD 96660 97413 98176 99145 100826 101545 101930 102117 103197 104080 104747 104839 107914 109675 109749 113538 113766 114386 114729 117207 117618 119727 121504 123227 123247 124314 125072 125595 131399 Other 1A 1118 - 61 2M1207 BPM 37093 Centaurus X-3 ( Krzeminski 's Star ) Centaurus X-4 Hen 3 - 600 NGC 5408 X-1 Nova Centauri 2013 Proxima Centauri PSR J1210 - 5226 4U 1145 - 619 4U 1323 - 62 WASP - 41 WR 50 WR 55 Star clusters Open IC 2944 NGC 3680 NGC 3766 NGC 3909 NGC 3960 NGC 4852 NGC 5043 NGC 5045 NGC 5138 NGC 5168 NGC 5281 NGC 5284 NGC 5316 NGC 5381 NGC 5460 NGC 5606 NGC 5617 NGC 5662 Stock 16 Globular NGC 5286 Omega Centauri Ruprecht 106 Nebulae HII IC 2944 Reflection NGC 5367 Planetary Fleming 1 He 2 - 108 He 2 - 111 Hen 2 - 90 NGC 3699 NGC 3918 NGC 5307 PB 8 Southern Crab Nebula SNR G292. 0 + 1.8 G296. 5 + 10.0 RCW 86 Galaxies NGC 3533 3557 3557B 3564 3568 3573 3706 3742 3749 3778 3783 3882 3903 4112 4219 4219A 4373 4373A 4373B 4444 4499 4507 4553 4573 4574 4575 4601 4603 4603A 4603B 4603C 4603D 4616 4622 4622A 4622B 4645 4645A 4645B 4650 4650A 4661 4672 4677 4679 4681 4683 4696 4696A 4696B 4696C 4696D 4696E 4706 4709 4729 4730 4743 4744 4751 4767 4767A 4767B 4785 4811 4812 4832 4835 4835A 4903 4905 4909 4930 4936 4940 4945 4945A 4946 4947 4947A 4950 4953 4976 4988 5011 5011A 5011B 5011C 5026 5062 5063 5064 5082 5090 5090A 5090B 5091 5102 5108 5114 5121 5121A 5124 5126 5140 5156 5161 5188 5193 5193A 5206 5215A 5215B 5220 5234 5237 5244 5253 5266 5266A 5291 5292 5298 5302 5304 5333 5357 5365 5365A 5365B 5397 5398 5408 5419 5483 5488 5489 5494 5516 5786 Other Centaurus A ESO 323 - G077 2GFL J1311. 7 - 3429 IC 3370 IC 3639 IC 4296 IC 4329 IC 4329A IRAS 13244 - 3809 MCG - 6 - 30 - 15 PKS 1144 - 379 PKS 1424 - 41 QSO B0241 + 622 Galaxy clusters Abell 3532 Abell 3556 Abell 3558 Abell 3562 Abell 3571 Abell 3574 Abell S740 Centaurus A Group Centaurus Cluster Other GRB 020405 Shapeley Supercluster SN 185 SN 1895B SN 1972E SN 1986G Retrieved from `` https://en.wikipedia.org/w/index.php?title=Alpha_Centauri&oldid=843197413 '' Categories : Alpha Centauri Centaurus ( constellation ) G - type main - sequence stars K - type main - sequence stars M - type main - sequence stars Solar analogs Triple star systems Multi-star planetary systems Stars with proper names Bayer objects Henry Draper Catalogue objects Hipparcos objects HR objects Durchmusterung objects Gliese and GJ objects Astronomical objects discovered in 1689 Astronomical objects known since antiquity Planetary systems Hidden categories : Pages containing links to subscription - only content Articles with Chinese - language external links CS1 German - language sources ( de ) Articles containing Arabic - language text All articles with unsourced statements Articles with unsourced statements from September 2014 Articles containing Chinese - language text Use dmy dates from December 2017 Use British English Oxford spelling from September 2016 Use British English from February 2017 Articles containing video clips Talk Contents About Wikipedia Afrikaans Aragonés Asturianu Azərbaycanca বাংলা Беларуская Български Boarisch Bosanski Català Čeština Dansk Deutsch Ελληνικά Español Esperanto Euskara فارسی Français Gaeilge Galego 한국어 Hawaiʻi हिन्दी Hrvatski Ido Bahasa Indonesia Italiano עברית Basa Jawa ಕನ್ನಡ ქართული Kiswahili Kurdî Latina Latviešu Lietuvių Magyar Македонски മലയാളം मराठी Bahasa Melayu မြန်မာဘာသာ Nederlands नेपाली 日本 語 Norsk Norsk nynorsk Occitan Oʻzbekcha / ўзбекча ਪੰਜਾਬੀ پنجابی Polski Português Română Runa Simi Русский Scots Simple English سنڌي Slovenčina Slovenščina کوردی Српски / srpski Srpskohrvatski / српскохрватски Suomi Svenska Tagalog தமிழ் Татарча / tatarça ไทย Lea faka - Tonga Türkçe Українська اردو Tiếng Việt Winaray 粵語 中文 Lingua Franca Nova 72 more Edit links This page was last edited on 27 May 2018, at 15 : 18. Text is available under the Creative Commons Attribution - ShareAlike License ; additional terms may apply. By using this site, you agree to the Terms of Use and Privacy Policy. Wikipedia ® is a registered trademark of the Wikimedia Foundation, Inc., a non-profit organization. About Wikipedia

Question: what is the distance from the sun to alpha centauri
Answer: 4.37 light-years (1.34 pc)