Alpha Centauri

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Double star
Alpha Centauri
The size and color of the Sun compared to the stars Alpha Centauri A, Alpha Centauri B, and Proxima Centauri
The size and color of the Sun compared to the stars Alpha Centauri A, Alpha Centauri B, and Proxima Centauri
Observation
dates equinox :  J2000.0 , epoch : J2000.0
AladinLite
Constellation centaur
Apparent brightness  −0.27 mag
Known exoplanets

1

Astrometry
Radial velocity −22.3 km / s
parallax 737 mas
distance  4.34 ± 0.03 ly
(1.33 ± 0.01 pc )
Absolute visual brightness M vis 4.13 mag
Proper movement :
Rec. Share: −3678.19 mas / a
Dec. portion: +481.84 mas / a
orbit 
period 79.9 a
Major semi-axis 17.59 "/ 23.9 AU
eccentricity 0.519
Periastron 11.5 AU
Apastron 36.3 AU
Orbit inclination 79.205 °
Argument of the node 204.85 °
Epoch of the periastron 1875.66
Argument of the periapsis 231.65 °
Individual data
Names A ; B.
Observation data:
Right ascension A. 14 h 39 m 36.5 s
B. 14 h 39 m 35.08 s
declination A. 1394997.69−60 ° 50 ′ 02.31 ″
B. 1394986.24−60 ° 50 ′ 13.76 ″
Apparent brightness A. −0.003 ± 0.006 mag
B. 1.333 ± 0.014 mag
Typing:
Spectral class A. G2 V
B. K1 V
B − V color index A. 0.65
B. 0.85
U − B color index A. 0.24
B. 0.64
Physical Properties:
Absolute vis.
Brightness M vis 		A. 4.40 mag
B. 5.74 likes
Dimensions A. 1.105 ± 0.0070 M ☉
B. 0.934 ± 0.0061 M ☉
radius A. 1.224 ± 0.003 R ☉
B. 0.863 ± 0.005 R ☉
Luminosity A. 1.522 ± 0.030 L ☉
B. 0.503 ± 0.020 L ☉
Effective temperature A. 5810 ± 50 K
B. 5260 ± 50 K
Metallicity [Fe / H] A. 0.22 ± 0.05
B. 0.24 ± 0.05
Rotation time A. 22 d
B. 41 d
Age 6.52 ± 0.3 billion a
Other names
and catalog entries
Bayer name α Centauri
SAO catalog SAO 252838 [1]
Tycho catalog TYC 9007-5849-1 [2]
Bright Star Catalog HR 5459 HR 5460
Henry Draper Catalog HD 128620 HD 128621
Hipparcos catalog HIP 71683 HIP 71681
Further designations: Toliman, Rigil Kentaurus, Rigilkent, Bungula, GJ 559, FK5 538

Template: Infobox double star / maintenance / single coordinates

Alpha Centauri [ alfa ʦɛntaʊ̯ʀi ] ( α Centauri, abbreviated α Cen, but also Rigil Kentaurus, Rigilkent, Toliman or Bungula called) is in the constellation of the Centaur the southern sky an approximately 4.34  light years distant binary system . It forms together with orbiting him, 0.22  Lj of Alpha Centauri remote sun next red dwarf Proxima Centauri (about 4.2421 Lj distance from the sun) a hierarchical triple-star system. Alpha Centauri consists of the lighter yellow star Alpha Centauri A and the orange-colored Alpha Centauri B, currently 6 ″ apart. Together with the sun, it is in the so-called local flake . Another star of the first magnitude is Beta Centauri only 4.4 ° to the west .

As a telescopic double star (only separable in a telescope), Alpha Centauri is the brightest object in the constellation and the third brightest star in the night sky with an apparent total brightness of −0.27 mag. The brighter Alpha Centauri A alone has an apparent magnitude of −0.01 mag, making it the fourth brightest star in the sky.

Location in the starry sky

Alpha Centauri is the brightest star in the constellation Centaurus (top left). In the treetop is the constellation Crux.

Alpha Centauri and the 4.4 ° distant Beta Centauri as well as the three brightest stars from the constellation Cross of the South , which lies west of the Centaur, together form the clearest cluster of stars of the 1st magnitude within a hand span in the entire starry sky.

The line through Alpha and Beta Centauri points to the Southern Cross constellation . The "pointers" were so named to easily distinguish between the Southern Cross and the eastern asterism , which is often confused with it (a cluster of stars that is mistaken for a constellation), the "False Cross" (the constellation Sail of the Ship or Vela) to be able to distinguish. The “false cross” includes the stars ε Car , Turais , κ Vel and δ Vel , which are visible to the naked eye .

Alpha and Beta Centauri are too far south to be seen from mid-northern latitudes (e.g. Europe). From latitude 33 ° south the two stars are circumpolar and therefore always stay above the horizon.

Alpha Centauri as a binary star system

Apparent and actual orbit of Alpha Centauri. The movement of component B relative to component A is shown. The narrow ellipse describes the apparent orbit as seen by an observer on earth. The perpendicular view of the orbit (large ellipse) makes the actual position clear.

The double star has an absolute magnitude of 4.1  mag . The two components A and B cannot be separated from the earth with the naked eye. The individual stars can only be seen in a telescope with a 5 cm aperture .

Once in 79.9 years, the two stars orbit each other on strongly elliptical orbits with an eccentricity of 0.519, the distance between 11.5 and 36.3  AU . The major semi-axis is around 23.9 AU. In May 1995 the greatest distance ( Apastron ) was reached. The closest approach (periastron) will take place in May 2035.

From the values ​​of the semi-axes and the period of revolution, the total mass of the binary star system can be calculated to be 2.08 solar masses.

The angular distance and the position angle change noticeably within a few years due to the relatively short period of rotation (see table). During one orbit, the apparent distance varies between approximately 2 "and 22".

The position of B relative to A
year Angular distance Position angle
1990 19.7 ″ 215 °
1995 17.3 ″ 218 °
2000 14.1 ″ 222 °
2005 10.5 ″ 230 °
2010 6.8 ″ 245 °

Most of the currently determined distances of the three stars mentioned in the literature are based on the parallax values ​​of the Hipparcos Star Catalog (HIP) from 1991.

Physical Properties

Alpha Centauri A and B are about 6.5 ± 0.3 billion years old as a pair of stars that formed together. Both are ordinary main sequence stars and are therefore in a stable phase of hydrogen burning ( fusion of hydrogen to helium ). Since Alpha Centauri A is more massive than Alpha Centauri B, it stays in the main sequence for a shorter time before evolving into a red giant . In contrast to the smaller and therefore more durable Alpha Centauri B, Alpha Centauri A has already had more than half of its life. Proxima Centauri, on the other hand, is only around 4.85 billion years old.

About Alpha Centauri A and B, which together are often also called α Cen AB, there are detailed observations of the surface vibrations from which asteroseismology can draw conclusions about the inner structure of the stars. If you combine this with traditional observation methods, you get more precise values ​​about the properties of the stars than would be possible with the individual methods.

Comparison of the element distribution in percent by mass
Surname hydrogen helium heavy elements
α Centauri A 71.5 25.8 2.74
α Centauri B 69.4 27.7 2.89
Sun 73.3 24.5 1.81

Alpha Centauri A

Like the sun, Alpha Centauri A is a yellow dwarf of the spectral type G2 V. Like the sun, it belongs to the hotter G stars (within the spectral class G, the numerical designation ranges from 0 (hottest) to 9 (coolest) star). The luminosity class  V indicates that it belongs to the main sequence stars . He is a apparent magnitude of 0.00  likes (magnitude) after Sirius (-1.46 mag), Canopus (-0.72 mag) and Arcturus (-0.05 mag) before Wega (0.03 mag) of fourth brightest star in the night sky.

Since Alpha Centauri A is of the same spectral type and has similar dimensions as the sun, it is considered to be the closest " solar twin " (but this does not mean that they were created together). Its surface temperature is about 5800  K . With 1.22 times the solar diameter, it is larger than Alpha Centauri B. It has 1.1 solar masses and emits 1.52 times as much radiation power as the sun. The chemical composition is very similar to that of the sun. The proportion of heavy elements (elements with an atomic number greater than helium are referred to as metals in astrophysics ) is, however, almost 70% higher (the metallicity is [Fe / H] A  = 0.22 ± 0.05). Its habitable zone is between 1.2 and 1.3  astronomical units (AU).

Alpha Centauri B

Alpha Centauri B belongs to the K1 spectral type with luminosity class  V. Compared to the brighter star Alpha Centauri A, it has a brightness of only 1.33 mag, making it number 21 in the list of the brightest stars in the sky. It has 0.93 solar masses and 0.86 times the solar diameter. It is also composed similarly to the sun. The proportion of heavy elements is, however, a good 70% higher (the metallicity is [Fe / H] B  = 0.24 ± 0.05). A rotation period of 41 days was found. For comparison: the sun rotates once around its own axis every 25 days.

With a surface temperature of around 5300 K, it is only slightly cooler than the sun. Due to the lower temperature and the smaller surface, however, it only achieves 50% of the solar radiation output. Thus, the brightness of the orange-yellow shining K1-V star Alpha Centauri B is only one third of the larger star Alpha Centauri A. The habitable zone lies at a distance of 0.73 to 0.74 AU.

Although it is less bright than Alpha Centauri A, Alpha Centauri B emits more energy in the X-ray part of the spectrum. The light curve of B varied at short intervals and at least one flare was observed.

Comparison of important stellar parameters
Surname Diameter
[million km] 		Radius
[R sun ] 		Mass
[M sun ] 		Luminosity
[L sun ] 		Spectral class
α Centauri A 1.70 1.22 1.1 1.52 G2 V
α Centauri B 1.20 0.86 0.93 0.50 K1 V
Sun 1.39 1 1 1 G2 V

Affiliation of Proxima Centauri to the star system

The actual positions of α Cen A and B (image taken by ESO's 1.5-meter CTIO telescope in Chile). Proxima Centauri would be 1 image width outside (bottom right).

The distance from Proxima Centauri to the binary star system Alpha Centauri A and B is about 12,900 AU or 0.204 light years. This corresponds to about 1000 times the distance between α Cen A and B itself, or 500 times the distance from Neptune to the sun. The angular distance from Proxima Centauri to Alpha Centauri A and B in the sky is about 2.2 degrees (four full moon widths).

The membership of Proxima Centauri Alpha Centauri has applied since November 2016 as given. The basis is the study of a research group led by Pierre Kervella and Frederic Thévenin. According to this, Proxima Centauri is gravitationally bound to the pair of stars and orbits it in about 600,000 years with an orbital eccentricity of about 0.42 at 9,100 AU mean distance (shortest distance about 5,300 AU, longest about 12,900 AU, i.e., Proxima Centauri is currently close to it Apoastron ). Proxima Centauri can thus also as Alpha Centauri C are called.

Older, highly precise astrometric measurements such as those of the Hipparcos satellite already indicated this affiliation (the information on the orbital period fluctuated between a few 100,000 years up to a few million years ). Older studies from 1994 left the possibility open that Proxima Centauri forms a movement cluster together with the inner binary star system and nine other star systems . As a result, Proxima Centauri would not orbit the pair Alpha Centauri in a stable motion, but its orbit would be hyperbolically disturbed by the binary star system, so that Proxima Centauri would never complete a full orbit around Alpha Centauri A and B. Similarly, according to a paper published in 2006, some radial velocity measurements, e.g. B. in the Gliese catalog, from the values ​​expected for a gravitationally bound system, so that it cannot be ruled out that it is just a random star encounter. This assumption was neither confirmed nor refuted by simulation calculations which, based on the calculated binding energy of the system, resulted in a bound system in 44% of the examined possibilities.

Move

The distances of the stars closest to the Sun over a period of 20,000 years in the past to 80,000 years in the future.
Apparent movement from Alpha Centauri towards Beta Centauri (Agena). In 6048 AD, the closest approach to β Cen will be reached. The Southern Cross is visible on the right.

The Alpha Centauri system moves obliquely towards the solar system and reduces the distance with a radial speed of around 22 km / s. Proxima Centauri, on the other hand, only approaches the sun at 16 km / s.

In a thousand years, Alpha Centauri will move about one degree (two full moon widths) in the sky. In 4,000 years it will have visually approached Beta Centauri so closely that they form what appears to be a double star. In reality, however, Beta with 520 ly is around 120 times further from the Sun than Alpha Centauri, and its proper motion is only around 1% that of Alpha.

In about 28,000 years the Alpha Centauri system will approach its closest approach at a distance of 3 ly to the solar system and then increase the distance again. It will stand on the border of the constellations water snake (Hydra) and sails of the ship and may get light up to −1.28 - only a little weaker than Sirius .

In the distant future, the star will slowly disappear under the stars of the Milky Way . Then the formerly dominant star in the inconspicuous constellation Telescope will fall under free-eyed visibility. This unusual position is explained by Alpha Centauri's own independent galactic movement, which is highly tilted with respect to the Milky Way.

Possibility of planet formation

Current computer models of planetary formation calculated that terrestrial planets could form close to Alpha Centauri A as well as Alpha Centauri B. Supporting these results is the discovery of planets in a binary star system such as Gamma Cephei , the high metallicity of the Alpha Centauri system, and the existence of numerous satellites around Jupiter and Saturn .

According to a work published in December 2017, previous measurements may have missed planets of up to 53 earth masses that orbit Alpha Centauri A in its habitable zone, or those of up to 8.4 earth masses for Alpha Centauri B.

However, gas giants such as Jupiter and Saturn , which cannot form in a binary star system due to the gravitational disturbances, can be safely ruled out . It is therefore not surprising that to date no abnormalities in the radial velocity that indicate such have been found. Because there are no gas giants, some astronomers assume that a possibly existing terrestrial planet in the Alpha Centauri system could be dry. This is based on the assumption that gas giants like Jupiter and Saturn are crucial for the fact that comets are steered into the interior of a star system and bring water to the planets through impacts. It may be that this effect occurs despite the absence of the gas planets, provided Alpha Centauri A would take on the role of Jupiter for Alpha Centauri B or vice versa. It is also conceivable that Proxima Centauri in the periastron could deflect a lot of comets from the Oort cloud of the system and thus supply possible terrestrial planets around the stars A and B with water. Since no Oort cloud has yet been detected, there is also the possibility that it was completely destroyed during the formation of the system.

The distance up to which stable orbits are possible for planets in a binary star system is not yet fully understood. For Alpha Centauri A the assessments vary from 1.2 AU to half the perihelion distance of 6.5 AU. Otherwise, they could be torn out of their original orbit when they are formed or only later due to gravitational disturbances by Alpha Centauri B.

In order to detect Earth-like planets in the habitable zone of Sun-like stars using the method of measuring radial velocity, very precise measurements on the order of centimeters per second are necessary. The "wobbling" of the central star , caused by the gravity of planets, is measured. Alpha Centauri seems to be well suited for these measurements because its activity (oscillation of the star, eruptions in the chromosphere ) is very small. It can be assumed that data will have to be collected for a few years in order to prove a possible planet.

Alpha Centauri Bb

The European Southern Observatory announced the discovery of Alpha Centauri B accompanying planet on October 16, 2012 Alpha Centauri Bb with. In 2015, an investigation was published that confirmed existing doubts about the existence of the planet, and in the same year the discoverer Xavier Dumusque recognized that the planet's signal was probably wrong.

Conditions for life

Based on the similarity of the two stars in terms of age, star type, spectral type and stability of the orbits , it is assumed that this star system could offer good conditions for extraterrestrial life . A planet around Alpha Centauri A would have to have a distance of about 1.2 to 1.3  AU to show temperatures similar to Earth. In relation to the solar system, this would roughly correspond to an orbit between Earth and Mars . For the less bright, cooler Alpha Centauri B, this distance would have to be about 0.73 to 0.74 AU (about the distance from Venus to the Sun).

The sky over Alpha Centauri

starry sky

The sun as seen from Alpha Centauri in Celestia

Seen from the Alpha Centauri system, the sky presents itself to an observer in a manner similar to that seen from the earth. Most of the constellations like Ursa Major and Orion look almost unchanged. In the constellation Centaurus, of course, the brightest star is missing. In contrast, the sun appears as a 0.5 mag bright star in the constellation Cassiopeia . The \ / \ / of Cassiopeia turns into a / \ / \ /, and instead of Segin (ε Cas) the sun forms the new eastern end of the constellation. The sun is antipodal (in the opposite direction) to the position of Alpha Centauri as seen from the earth, i.e. at the coordinates RA 02 h 39 m 35 s and DE + 60 ° 50 ′ 7 ″ ± 5 ″ . 23935 2605007

Closer bright stars like Sirius , Altair and Prokyon can be seen in clearly shifted positions. Sirius now belongs to the constellation Orion and stands 2 degrees west of Betelgeuse , although he does not have the same brightness of −1.46 as seen from Earth, but only −1.2. The slightly more distant stars Fomalhaut and Vega also appear somewhat offset. Despite its short distance of 13,500 AU (a quarter of a light year), Proxima Centauri is only an inconspicuous star with a magnitude of 4.5 mag. This shows how faint this red dwarf is.

The closest larger neighboring stars of the Alpha Centauri system are after the sun (distance 4.34 ly) with a distance of 6.47 ly Barnard's arrow star , with 9.5 ly Sirius and with 9.7 ly Epsilon Indi . Barnard's star is also the second closest star to the Sun with a distance of 5.96 ly.

The two suns

An observer on a hypothetical planet around Alpha Centauri A or B sees the other star as a very bright object. An earth-sized planet that orbits Alpha Centauri A at a distance of 1.25 AU (this corresponds roughly to the middle between Earth and Mars orbit ) (and would need about 1.34 years), receives from it about the amount of light that the Earth receives from the sun. Alpha Centauri B appears between 5.7 and 8.6 mag "darker" (−21 to −18.2 mag) depending on its position in its orbit. This is 190 to 2700 times fainter than Alpha Centauri A, but still about the same factor brighter than the full moon.

At Alpha Centauri B, an earth-sized planet would have to orbit the star at a distance of 0.7 AU (corresponds to an orbital period of just over 0.6 years) in order to receive the same amount of radiation as the earth from the sun. Alpha Centauri A then radiates, depending on its position in orbit, with around 4.6 to 7.3 mag (−22.1 to −19.4 mag), weaker than the main star. That is 70 to 840 times fainter than Alpha Centauri B, but still 520 to 6300 times brighter than the full moon.

In both cases one has the impression when observing that the "second sun" orbits the sky in the course of a planetary year. Assuming a low orbital inclination of the planetary orbit of Alpha Centauri A compared to Alpha Centauri B, the two stars will be close to each other in the course of a planetary orbit and half a "year" later the secondary star will be seen as the midnight sun. After another six months, this cycle is over and both stars - at different distances - are again in the sky as double stars. The distance between the two stars changes in the course of their elliptical circling around one another, i.e. H. within 80 years the distant star slowly moves away (~ 36 AU) and then comes closer again to 11.5 AU.

For a hypothetical Earth-like planet around one of the two stars, the second sun is not bright enough to significantly affect the climate - even if it can get about as close as Saturn to the sun. Nevertheless, the more distant star ensures that it illuminates the night sky for six months so that it looks dark blue instead of pitch black. One could easily read without additional light.

Naming

"Alpha Centauri" is a name according to the Bayer classification . Alpha  (α) is the first letter of the Greek alphabet, and Centauri (the genitive of Latin Centaurus, the Centaur ) indicates that it belongs to the constellation Centaur .

The proper name Rigil Kentaurus (often abbreviated as Rigil Kent. ) Earlier Rigjl Kentaurus and Riguel Kentaurus (in Portuguese) is from the Arabic phrase Rijl Qan t ūris (or Rijl al-Qan t ūris; رجل قنطورس, DMG riǧl qanṭūris ) and means "foot of the centaur ".

The name Toliman (also incorrectly Tolimann ) comes either from the Arabic (الظلمان, DMG aẓ-ẓulmān ) or the Hebrew language. In Arabic it means "bouquets" and in Hebrew as much as "before and after" or "shoot of the vine".

The name Bungula , which is rarely used nowadays , was probably formed from "β" and from the Latin ungula ("hoof") and, like Rigil, denotes the centaur's front leg .

In the Chinese language Alpha Centauri is called Nánmén'èr (南門 二), "Second star of the southern gate" (as mentioned, Alpha and Beta Centauri together form the "southern pointer" to the constellation Southern Cross).

Usually the double star is called Alpha Centauri after the Bayer name .

history

Alpha Centauri AB above the horizon of Saturn , captured by Cassini on May 17, 2008

Alpha Centauri was already known to the ancient Greeks . But as a result of the continual precession of the earth's axis, it wandered below the European horizon and was finally forgotten.

The Inca used in Kenko two cylindrically shaped, closely juxtaposed stones, which peaked about 20 centimeters and a visor stones in the star observation, in particular the Plejaden and Alpha Centauri served.

The explorer Amerigo Vespucci mapped Alpha Centauri, Beta Centauri and the Southern Cross constellation after the first half of his last voyage (1501 to 1502) .

The discovery of the binary star nature is attributed to the Jesuit priest Jean Richaud, who is said to have established this in December 1689 in Pondicherry, India, while observing a nearby comet with a telescope.

The apparent proper motion of Alpha Centauri was determined on the basis of the astrometric observation data of the French astronomer Abbé de La Caille 1751 to 1752.

Thomas James Henderson , a Scottish astronomer, was the first to calculate the distance to Alpha Centauri at the Cape Observatory . Between April 1832 and May 1833 he measured the annual trigonometric parallax of both stars. He determined the high proper motion of the star and concluded that Alpha Centauri must be a particularly close star. After measuring the parallax of 1.16 ± 0.11 arcseconds, he came to the conclusion that Alpha Centauri was a little less than 1  parsec (3.26 ly) away. The value was 33.7% too low, but at that time it was already relatively accurate. However, he has not yet published the results because he seriously questioned them because of the high values. It was not until 1839, after Friedrich Wilhelm Bessel had published his own precise measurements of the parallax of 61 Cygni in 1838 , that he published his results. Alpha Centauri is therefore officially the second star whose distance has been calculated.

Flag of South Australia (1870)

In 1870 there was the first flag of South Australia. It contained the Southern Cross, with the two stars Alpha Centauri and Beta Centauri serving as landmarks. The Southern Cross is still included in the current flag of Australia .

In 1926 William Stephen Finsen published the parameters of the orbital elements of Alpha Centauri A and B. The future positions could now be calculated in ephemeris (tables that list the positions of moving astronomical objects). Other astronomers such as D. Pourbaix in 2002 made little corrections to the orbit and orbital elements. The eighty-year period for α Centauri AB is therefore fairly accurate.

Culture

Since Alpha Centauri is the star system closest to the sun, it is often a topic in science fiction - such as in the film Avatar , in the novel The Three Suns - or in video games such as Sid Meier's Alpha Centauri , Civilization or the first-person shooter series Killzone . Play interstellar travel , the human exploration and the discovery and colonization of possible planet a role. Also in the Netflix series Lost in Space , Alpha Centauri is built into the plot as a colony of former citizens.

In alpha-Centauri , a series of broadcasts by Bayerischer Rundfunk, Harald Lesch answered individual questions from physics - especially astronomy and astrophysics - in a popular scientific form in 15-minute episodes .

See also

literature

  • D. Pourbaix, C. Neuforge-Verheecke, A. Noels: Revised masses of Alpha Centauri . In: European Southern Observatory (Ed.): Astronomy and Astrophysics . Vol. 344, No. 1 . Springer, 1999, ISSN  0004-6361 , p. 172–176 ( online [PDF; 218 kB ]).
  • Martin Beech: Alpha Centauri. Unveiling the Secrets of Our Nearest Stellar Neighbor. Springer, Cham 2015, ISBN 978-3-319-09371-0 .

Web links

Wiktionary: Alpha Centauri  - explanations of meanings, word origins, synonyms, translations
Commons : Alpha Centauri  - album with pictures, videos and audio files

Remarks

  1. ↑ a b c The parallax of α Cen is 0.737 ″ (Pourbaix 1999). So an AE at this distance appears at an angle of 0.737 ". An angle of 17.57 ″ (large semi-axis, Pourbaix 1999) therefore corresponds to a distance of 17.59 / 0.737 = 23.9 AU. Smallest distance = large semi-axis (1 - eccentricity) = 11.5 AU, largest distance = large semi-axis (1 + eccentricity) = 36.3 AU.
  2. ↑
  3. ↑ Since Alpha Centauri moves in the direction of the sun and thus shortens the distance to it, the apparent proper movement will increase slightly in the future.

Individual evidence

  1. ↑ The 10 Brightest Stars. ( Memento of November 11, 2010 in the Internet Archive ).
  2. ↑ a b c d e f g h i j k P. Eggenberger, C. Charbonnel, S. Talon, G. Meynet, A. Maeder, F. Carrier, G. Bourban: Analysis of α Centauri AB including seismic constraints . In: Astronomy and Astrophysics . tape 417 , April 2004, p. 235–246 , doi : 10.1051 / 0004-6361: 20034203 , arxiv : astro-ph / 0401606 .
  3. ^ AstronomyOnline: Appendices and Other Various Tables.
  4. ↑ a b c d ARICNS 4C01151, ARICNS 4C01152. ARICNS ARI Data Base for Nearby Stars.
  5. ^ A b Hipparco's Catalog. ( Memento from July 4, 2012 on WebCite )
  6. ↑ a b c D. Pourbaix, C. Neuforge-Verheecke, A. Noels: Revised masses of α Centauri . In: Astronomy and Astrophysics . Les Ulis 1999, p. 172–176 ( full text [PDF; 224 kB ]). ISSN 0004-6361 .  
  7. ↑ a b SIMBAD Query Result: HD 128620 - High proper-motion Star.
  8. ↑ a b M. Bazot: Asteroseismology of α Centauri A. Evidence of rotational splitting. In: Astronomy and Astrophysics. Retrieved July 18, 2008 ( doi: 10.1051 / 0004-6361: 20065694 ).
  9. ↑ a b c Proxima’s orbit around alpha Centauri. (PDF; 259 kB) November 14, 2016, accessed on November 23, 2016 (English). ( arxiv : 1611.03495 ).
  10. ↑ a b Alpha Centauri. Retrieved February 24, 2008 .
  11. ↑ Andrew James: THE IMPERIAL STAR Page7. (No longer available online.) Andrew James, archived from the original on December 16, 2008 ; Retrieved May 3, 2008 .
  12. ^ R. Burnham Jr .: Burnham's Celestial Handbook . Dover / New York 1978, ISBN 0-486-23567-X , p. 549 .
  13. ↑ Hans Kjeldsen, Timothy R. Bedding, R. Paul Butler , Joergen Christensen-Dalsgaard, Laszlo L. Kiss, Chris McCarthy, Geoffrey W. Marcy , Christopher G. Tinney, Jason T. Wright: Solar-Like Oscillations in α Centauri B . In: The Astrophysical Journal . tape 635 , no. 2 , August 29, 2005, p. 1281–1290 , doi : 10.1086 / 497530 , arxiv : astro-ph / 0508609 .
  14. ^ AAO Anglo-Australian Observatory: Star near the southern cross is 'ringing'. (No longer available online.) December 22, 2005, archived from the original on March 22, 2012 ; accessed on January 24, 2016 .
  15. ↑ a b Stefan Taube: Portrait of a neighboring family. (No longer available online.) In: Astronomie.de. Archived from the original on May 29, 2008 ; Retrieved May 2, 2008 .
  16. ↑ a b c d P. A. Wiegert, MJ Holman: The stability of planets in the Alpha Centauri system . In: The Astronomical Journal . tape 113 , no. 4 , April 1997, p. 1445–1450 , doi : 10.1086 / 118360 , arxiv : astro-ph / 9609106 .
  17. ↑ J. Robrade: X-rays from α Centauri - The darkening of the solar twin . In: Astronomy and Astrophysics . 2005, bibcode : 2005A & A ... 442..315R .
  18. ↑ Jeremy G. Wertheimer, Gregory Laughlin: Are Proxima and α Centauri Gravitationally Bound? In: The Astronomical Journal . tape 132 , no. 5 , October 2006, p. 1995–1997 , doi : 10.1086 / 507771 , arxiv : astro-ph / 0607401 .
  19. ^ Robert Matthews, Gerard Gilmore: Is Proxima really in orbit about Alpha CEN A / B? In: Monthly Notices of the Royal Astronomical Society . tape 261 , February 1993, p. L5 , bibcode : 1993MNRAS.261L ... 5M .
  20. ↑ Andrew James: THE IMPERIAL STAR Page5. (No longer available online.) Andrew James, archived from the original on December 16, 2008 ; Retrieved May 3, 2008 .
  21. ^ EV Quintana, JJ Lissauer, JE Chambers, MJ Duncan: Terrestrial Planet Formation in the α Centauri System . In: The Astrophysical Journal . tape 576 , no. 2 , February 22, 2002, p. 982-996 , doi : 10.1086 / 341808 .
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  30. ↑ Devin Powell: Poof! The Planet Closest To Our Solar System Just Vanished . National Geographic. October 29, 2015. Retrieved January 15, 2015.
  31. ↑ Roland Brodbeck: The starry sky is three-dimensional. In: astro! Nfo. Retrieved May 27, 2008 .
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