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51 Pegasi
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Star 51 Pegasi

Subgiant 51 Pegasi is located 51 light years away from the Sun. It is a single star of spectral class G2IV B, that has 111 % of solar mass. There is at least one exoplanet in this system.
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Sun distance
51 light years
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51 Pegasi

Subgiant, High proper motion star
Spectral class: G2IV B

Location +

Ascension iconRight ascension: 22h 57m 28.222s
Declination iconDeclination: 20° 46' 8.776'' (northern hemisphere)
Parallax iconParallax: 64.405
Distance iconSun distance: 50.642 ly | 15.5 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: 111 % M Sun
| 1163 M Jupiter
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Star mass
Mass of the star 51 Pegasi is 1.11 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: 124 % R Sun
| 12.3 R Jupiter
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Star size
Radius of the star 51 Pegasi is 1.237 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: 5805 K | 1 T Sun
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Star temperature
Surface temperature of 51 Pegasi is 5805 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: 6.1 billions years | 1.33 Sun
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Star age
Star 51 Pegasi is 6.1 billion years old, which is about 1.33 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: 1.36 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 iconApparent magnitude (V): 5.5
Magnitude iconAbsolute magnitude (V): 4.5
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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51 Pegasi system structure

 51 Pegasi
51 Pegasi b 0.05 AU 150.1 M⊕ 4.2 days

More about 51 Pegasi

Nearby star 51 Pegasi is a main sequence star that fuses hydrogen atoms into helium. It is is approximately 24 % bigger than the Sun and temperature on its surface is around 5805 K (5532 °C), which is about 100 % of Sun's temperature.
       51 Pegasi can be found in northern celestial hemisphere, and it is possible to see it with naked eye. The star is easily observable from Northern America, Europe and Asia.
Other designations of this star
Helvetios, 51 Peg, Gliese 882, GJ 882, HR 8729, BD +19°5036, HD 217014, LTT 16750, NLTT 55385, GCTP 5568.00, SAO 90896, HIC 113357, HIP 113357, GC 32003, 2MASS J22572795+2046077, TIC 139298196, TYC 1717-2193-1, WDS J22575+2046A, Gaia EDR3 2835207319109249920
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External sources
icon study
An Outer Giant Planet or Brown Dwarf in the 51 Pegasi System?
Scientific study, Accepted: 11. 05. 2026
icon study
simbad icon
Simbad database (* 51 Peg)
Astronomical database SIMBAD (the Set of Identifications, Measurements and Bibliography for Astronomical Data)
gaia icon
Gaia database (Gaia EDR3 2835207319109249920)
Archive from the Gaia mission

Frequently Asked Questions

How far is the 51 Pegasi system from the Sun?

The 51 Pegasi system is 51 light years or 15.5 parsecs from the Sun.

What galaxy is the 51 Pegasi star in?

The 51 Pegasi is in the Milky Way galaxy just like the Sun.

How many stars are in the 51 Pegasi system?

The 51 Pegasi is a single star, there are no other known stars in the system.

What type of star is the 51 Pegasi?

The star 51 Pegasi is a Subgiant star.

What temperature is star 51 Pegasi?

The star 51 Pegasi has an effective temperature of 5805 K. Find out more about the temperature of stars in Stellar guide
Class of stars Subgiant
A subgiant is a term used to describe a luminous star that is typically running out of hydrogen for nuclear fusion and is thus departing from the main sequence. These stars are classified as Yerkes luminosity class IV.
Closest stars

 G 68-5
 - 5.3 ly

StKM 1-2065
 - 5.3 ly

2MASS J22443167+2043433
 - 5.7 ly

EGGR 155
 - 7.9 ly

Ksi Pegasi
 1.2 M☉ 8.7 ly
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