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Fomalhaut
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Star Fomalhaut

Triple star system Fomalhaut is located 25 light years away from the Sun. It is a system with 3 stars. There is at least one exoplanet in this system.
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Sun distance
25 light years
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Fomalhaut

White-Blue star
Spectral class: A3V C

Location +

Ascension iconRight ascension: 22h 57m 39.047s
Declination iconDeclination: -29° 37' 20.050'' (southern hemisphere)
Parallax iconParallax: 129.810
Distance iconSun distance: 25.130 ly | 7.7 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: 192 % M Sun
| 2011 M Jupiter
+
Star mass
Mass of the star Fomalhaut is 1.92 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: 184 % R Sun
| 18.3 R Jupiter
+
Star size
Radius of the star Fomalhaut is 1.842 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: 7671 K | 1.33 T Sun
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Star temperature
Surface temperature of Fomalhaut is 7671 K, which is 133 % 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: 0.44 billions years | 0.1 Sun
+
Star age
Star Fomalhaut is 0.44 billion years old, which is about 0.1 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: 16.63 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): 1.2
Magnitude iconAbsolute magnitude (V): 1.7
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

Fomalhaut B

Orange star, BY Draconis variable
Spectral class: K5Vp

Basic characteristic

icon weight
Mass: 72.5 % M Sun
| 759 M Jupiter
+
Star mass
Mass of the star Fomalhaut B is 1.92 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: 63 % R Sun
| 6.3 R Jupiter
+
Star size
Radius of the star Fomalhaut B is 0.629 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: 4573 K | 0.79 T Sun
+
Star temperature
Surface temperature of Fomalhaut B is 4573 K, which is 79 % 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: 0.44 billions years | 0.1 Sun
+
Star age
Star Fomalhaut B is 0.44 billion years old, which is about 0.1 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: 0.19 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): 6.5
Magnitude iconAbsolute magnitude (V): 7.1
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

Fomalhaut C

Red dwarf
Spectral class: M4V

Basic characteristic

icon weight
Mass: 18 % M Sun
| 189 M Jupiter
+
Star mass
Mass of the star Fomalhaut C is 0.725 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: 20 % R Sun
| 2 R Jupiter
(estimate)
+
Star size
Radius of the star Fomalhaut C is not known. Its estimated value based on other similar stars is about 20 % 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: 3143 K | 0.54 T Sun
+
Star temperature
Surface temperature of Fomalhaut C is 3143 K, which is 54 % 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

Photometry

Magnitude iconApparent magnitude (V): 12.6
Magnitude iconAbsolute magnitude (V): 13.2
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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Fomalhaut system structure

 Fomalhaut
Fomalhaut Dagon
unconfirmed
 177 AU 620500 days
Fomalhaut B
Fomalhaut C

More about Fomalhaut

      a BY Draconis variable. Stars from this category exhibit periodic variations in their luminosity. The variability is caused by a rotation which shows and hides starspots on the surface. Fomalhaut can be found in southern celestial hemisphere, and it is possible to see it with naked eye. The star is also observable from Northern America, Europe and Asia. 

      Fomalhaut is a BY Draconis variable. Stars from this category exhibit periodic variations in their luminosity. The variability is caused by a rotation which shows and hides starspots on the surface.
Other designations of this star
LP 876-10, Fomalhaut C, 2MASS J22480446-2422075, NLTT 54872, GSC 06964-01226, TW Piscis Austrini, TW PsA, Gl 879, HR 8721, CD -32°17321, HD 216803, LTT 9283, GCTP 5562.00, SAO 214197, CP(D)-32 6550, HIP 113283, α Piscis Austrini, α PsA, Alpha PsA, 24 Piscis Austrini, CPD −30° 6685, FK5 867, Gl 881, HD 216956, HIP 113368, HR 8728, SAO 191524, alf PsA
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External sources
icon study
A second planetesimal collision in the Fomalhaut system
Scientific study, Accepted: 18. 12. 2025
icon study
Fomalhaut's debris disc is not dominated by primordial Plutos
Scientific study, Accepted: 08. 10. 2025
icon study
icon study
Debris disks around main-sequence stars
Scientific study, Accepted: 18. 03. 2024
icon study
Searching for Planets Orbiting Fomalhaut with JWST/NIRCam
Scientific study, Accepted: 23. 10. 2023
icon study
simbad icon
Simbad database (* alf PsA C)
Astronomical database SIMBAD (the Set of Identifications, Measurements and Bibliography for Astronomical Data)
gaia icon
Gaia database (Gaia EDR3 6623351805412369024)
Archive from the Gaia mission

Frequently Asked Questions

How far is the Fomalhaut system from the Sun?

The Fomalhaut system is 25 light years or 7.7 parsecs from the Sun.

What galaxy is the Fomalhaut star in?

The Fomalhaut is in the Milky Way galaxy just like the Sun.

How many stars are in the Fomalhaut system?

The Fomalhaut system contains 3 stars.

What type of star is the Fomalhaut?

The primary in the Fomalhaut system is a White-Blue star star.

What temperature is star Fomalhaut?

The primary in the Fomalhaut system has a temperature of 7671 K. Find out more about the temperature of stars in Stellar guide
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