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Alpha Centauri
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Star Alpha Centauri

Triple star system Alpha Centauri is located 4 light years away from the Sun. It is a system with 3 stars. There are multiple known exoplanets in this system.
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Sun distance
4 light years
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Alpha Centauri

Yellow star, Spectroscopic binary
Spectral class: G2V

Location +

Ascension iconRight ascension: 14h 39m 36.494s
Declination iconDeclination: -60° 50' 2.374'' (southern hemisphere)
Parallax iconParallax: 743.000
Distance iconSun distance: 4.370 ly | 1.3 pc
Star position
The position of a star tells us where it appears in the sky, similar to how we use coordinates like latitude and longitude on Earth. In astronomy, the three main coordinates are right ascension, declination and distance. .. icon More about Star position in StellarGuide

Basic characteristic

icon weight
Mass: 110 % M Sun
| 1152 M Jupiter
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Star mass
Mass of the star Alpha Centauri is 1.1 solar masses.

The mass of a star is the total amount of matter it contains. It is one of the most important properties of a star, as it determines almost everything about how the star lives, changes, and dies. In astronomy, star mass is usually measured in solar masses (M☉) — where 1 solar mass is equal to the mass of our Sun... icon More about Star mass in StellarGuide
radius icon
Size: 122 % R Sun
| 12.2 R Jupiter
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Star size
Radius of the star Alpha Centauri is 1.2234 solar radii.

The size of a star refers to its radius — the distance from its center to its surface. Star size is usually measured in solar radii (R☉), where 1 solar radius equals approximately 696,000 kilometers. Depending on their type and life stage, stars can be much smaller or larger than the Sun... icon More about Star size in StellarGuide
temperature icon
Temperature: 5753 K | 1 T Sun
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Star temperature
Surface temperature of Alpha Centauri is 5753 K, which is 100 % of the temperature on the surface of the Sun.

The temperature of a star refers to the temperature at its surface, also called the photosphere. It is measured in kelvins (K), the standard unit for temperature in astronomy. A star’s temperature tells us a lot about its physical properties and where it stands in its evolutionary stage... icon More about Star temperature in StellarGuide
time icon
Age: 5.2 billions years | 1.13 Sun
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Star age
Star Alpha Centauri is 5.2 billion years old, which is about 1.13 of the Sun's age.

The age of a star tells us how long it has been shining since it formed. Knowing a star’s age helps astronomers understand its life stage, how it has changed over time, and what will happen to it in the future... icon More about Star age in StellarGuide
luminosity icon
Luminosity: 1.519 L Sun
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Star luminosity
Luminosity is the total amount of energy a star gives off every second. Think of it as the star’s true brightness — not just how bright it looks from Earth. This is important because some stars may appear dim simply because they are far away, not because they’re actually faint... icon More about Star luminosity in StellarGuide

Photometry

Magnitude iconAbsolute magnitude (V): 4.4
Absolute stellar magnitude in different parts of the electromagnetic spectrum from infrared (K band) to ultraviolet (U band).
5
10
15
20
25
30
35
K
2.1
H
1.6
J
1.2
Grp
0.8
I
0.8
G
0.6
V
0.5
Gbp
0.5
B
0.4
U
0.3

Alpha Centauri B

Orange star, High proper motion star
Spectral class: K1V

Location +

Distance iconDistance from the primary: 17.493 AU

Basic characteristic

icon weight
Mass: 90.7 % M Sun
| 950 M Jupiter
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Star mass
Mass of the star Alpha Centauri B is 1.1 solar masses.

The mass of a star is the total amount of matter it contains. It is one of the most important properties of a star, as it determines almost everything about how the star lives, changes, and dies. In astronomy, star mass is usually measured in solar masses (M☉) — where 1 solar mass is equal to the mass of our Sun... icon More about Star mass in StellarGuide
radius icon
Size: 86 % R Sun
| 8.6 R Jupiter
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Star size
Radius of the star Alpha Centauri B is 0.8632 solar radii.

The size of a star refers to its radius — the distance from its center to its surface. Star size is usually measured in solar radii (R☉), where 1 solar radius equals approximately 696,000 kilometers. Depending on their type and life stage, stars can be much smaller or larger than the Sun... icon More about Star size in StellarGuide
temperature icon
Temperature: 5242 K | 0.91 T Sun
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Star temperature
Surface temperature of Alpha Centauri B is 5242 K, which is 91 % of the temperature on the surface of the Sun.

The temperature of a star refers to the temperature at its surface, also called the photosphere. It is measured in kelvins (K), the standard unit for temperature in astronomy. A star’s temperature tells us a lot about its physical properties and where it stands in its evolutionary stage... icon More about Star temperature in StellarGuide
time icon
Age: 5.3 billions years | 1.15 Sun
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Star age
Star Alpha Centauri B is 5.3 billion years old, which is about 1.15 of the Sun's age.

The age of a star tells us how long it has been shining since it formed. Knowing a star’s age helps astronomers understand its life stage, how it has changed over time, and what will happen to it in the future... icon More about Star age in StellarGuide
luminosity icon
Luminosity: 0.5002 L Sun
+
Star luminosity
Luminosity is the total amount of energy a star gives off every second. Think of it as the star’s true brightness — not just how bright it looks from Earth. This is important because some stars may appear dim simply because they are far away, not because they’re actually faint... icon More about Star luminosity in StellarGuide

Photometry

Magnitude iconApparent magnitude (V): 1.3
Magnitude iconAbsolute magnitude (V): 5.8
Absolute stellar magnitude in different parts of the electromagnetic spectrum from infrared (K band) to ultraviolet (U band).
5
10
15
20
25
30
35
K
2.1
H
1.6
J
1.2
Grp
0.8
I
0.8
G
0.6
V
0.5
Gbp
0.5
B
0.4
U
0.3

Proxima Centauri

Red dwarf, flare star, , High proper motion star
Spectral class: M5.5 Ve

Location +

Distance iconDistance from the primary: 8700 AU

Basic characteristic

icon weight
Mass: 12.2 % M Sun
| 128 M Jupiter
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Star mass
Mass of the star Proxima Centauri is 0.907 solar masses.

The mass of a star is the total amount of matter it contains. It is one of the most important properties of a star, as it determines almost everything about how the star lives, changes, and dies. In astronomy, star mass is usually measured in solar masses (M☉) — where 1 solar mass is equal to the mass of our Sun... icon More about Star mass in StellarGuide
radius icon
Size: 15.4 % R Sun
| 1.5 R Jupiter
+
Star size
Radius of the star Proxima Centauri is 0.1542 solar radii.

The size of a star refers to its radius — the distance from its center to its surface. Star size is usually measured in solar radii (R☉), where 1 solar radius equals approximately 696,000 kilometers. Depending on their type and life stage, stars can be much smaller or larger than the Sun... icon More about Star size in StellarGuide
temperature icon
Temperature: 2883 K | 0.5 T Sun
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Star temperature
Surface temperature of Proxima Centauri is 2883 K, which is 50 % of the temperature on the surface of the Sun.

The temperature of a star refers to the temperature at its surface, also called the photosphere. It is measured in kelvins (K), the standard unit for temperature in astronomy. A star’s temperature tells us a lot about its physical properties and where it stands in its evolutionary stage... icon More about Star temperature in StellarGuide
time icon
Age: 4.85 billions years | 1.05 Sun
+
Star age
Star Proxima Centauri is 4.85 billion years old, which is about 1.05 of the Sun's age.

The age of a star tells us how long it has been shining since it formed. Knowing a star’s age helps astronomers understand its life stage, how it has changed over time, and what will happen to it in the future... icon More about Star age in StellarGuide
luminosity icon
Luminosity: 0.00005 L Sun
+
Star luminosity
Luminosity is the total amount of energy a star gives off every second. Think of it as the star’s true brightness — not just how bright it looks from Earth. This is important because some stars may appear dim simply because they are far away, not because they’re actually faint... icon More about Star luminosity in StellarGuide

Photometry

Magnitude iconApparent magnitude (V): 11.1
Magnitude iconAbsolute magnitude (V): 15.6
Absolute stellar magnitude in different parts of the electromagnetic spectrum from infrared (K band) to ultraviolet (U band).
5
10
15
20
25
30
35
K
2.1
H
1.6
J
1.2
Grp
0.8
I
0.8
G
0.6
V
0.5
Gbp
0.5
B
0.4
U
0.3
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Alpha Centauri system structure

Stars A and B form a pair, which is orbited by the more distant star C.
 Alpha Centauri
Alpha Centauri B 17.493 AU
Proxima Centauri 8700 AU
Proxima Centauri d 0.03 AU 0.3 M⊕ 0.8 R⊕ 5.2 days
Proxima Centauri b 0.05 AU 1.2 M⊕ 1.1 R⊕ 11.2 days
Proxima Centauri c
unconfirmed
 1.48 AU 7.8 M⊕ 1928 days

More about Alpha Centauri

       Alpha Centauri can be found in southern celestial hemisphere, and it is possible to see it with naked eye.
Other designations of this star
Alpha Centauri C, CCDM J14396-6050C, GCTP 3278.00, Gliese 551, HIP 70890, LFT 1110, LHS 49, LPM 526, LTT 5721, NLTT 37460, V645 Centauri, Toliman, α2 Centauri, HR 5460, HD 128621, LHS 51, HIP 71681, alf Cen B, Gliese 559, FK5 538, CD−60°5483, CCDM J14396-6050, GC 19728, α Cen A, Rigil Kentaurus, Rigil Kent, α1 Centauri, HR 5459, HD 128620, GCTP 3309.00, LHS 50, SAO 252838, HIP 71683, alf Cen A
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External sources
icon study
Star-planet interaction in the Proxima system
Scientific study, Accepted: 21. 05. 2026
icon study
icon study
icon study
icon study
icon study
icon study
icon study
Simulating RISTRETTO: Proxima b detectability in reflected light
Scientific study, Accepted: 09. 09. 2025
icon study
icon study
simbad icon
Simbad database (NAME Proxima Centauri)
Astronomical database SIMBAD (the Set of Identifications, Measurements and Bibliography for Astronomical Data)
gaia icon
Gaia database (Gaia EDR3 5853498713190525696)
Archive from the Gaia mission

News from this star system

The three nearest Sun-like stars and their exoplanets
Image: The three nearest Sun-like stars and their exoplanets
...
13.9.2026
Read article >
Magnetic interactions found between Proxima Centauri and its planets
Image: Magnetic interactions found between Proxima Centauri and its planets
Proxima Centauri’s two planets show magnetic interactions with their star. Flares are phase-locked to the inner planet’s orbit, and both planets influence stellar activity...
25.5.2026
Read article >
TOLIMAN: a small space telescope to search for planets around Alpha Centauri
Image: TOLIMAN: a small space telescope to search for planets around Alpha Centauri
TOLIMAN, a small and affordable space telescope, will use precise astrometry to search for Earth-like planets around Alpha Centauri, our nearest stellar neighbors....
17.3.2026
Read article >

Frequently Asked Questions

How far is the Alpha Centauri system from the Sun?

The Alpha Centauri system is 4 light years or 1.3 parsecs from the Sun.

What galaxy is the Alpha Centauri star in?

The Alpha Centauri is in the Milky Way galaxy just like the Sun.

How many stars are in the Alpha Centauri system?

The Alpha Centauri system contains 3 stars.

What type of star is the Alpha Centauri?

The primary in the Alpha Centauri system is a Yellow star star.

What temperature is star Alpha Centauri?

The primary in the Alpha Centauri system has a temperature of 5753 K. Find out more about the temperature of stars in Stellar guide
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 1 M☉ 4.2 ly

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 0.14 M☉ 6.6 ly

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 0.17 M☉ 8.3 ly
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