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Alpheratz
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Star Alpheratz

Binary star Alpheratz is located 97 light years away from the Sun. It consists of a subgiant and a white-blue star. For now, there are no known exoplanets in this star system.
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Sun distance
97 light years
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Alpheratz A

Subgiant
Spectral class: B8IV-VHgMn

Location +

Ascension iconRight ascension: 0h 8m 23.264s
Declination iconDeclination: 29° 5' 25.552'' (northern hemisphere)
Parallax iconParallax: 33.620
Distance iconSun distance: 97.012 ly | 29.7 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: 363 % M Sun
| 3803 M Jupiter
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Star mass
Mass of the star Alpheratz A is 3.63 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: 294 % R Sun
| 29.3 R Jupiter
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Star size
Radius of the star Alpheratz A is 2.94 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: 11950 K | 2.07 T Sun
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Star temperature
Surface temperature of Alpheratz A is 11950 K, which is 207 % 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: 200 billions years | 43.48 Sun
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Star age
Star Alpheratz A is 200 billion years old, which is about 43.48 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: 158 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): 2.2
Magnitude iconAbsolute magnitude (V): -0.1
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

Alpheratz B

White-Blue star
Spectral class: A7V

Basic characteristic

icon weight
Mass: 187.5 % M Sun
| 1964 M Jupiter
+
Star mass
Mass of the star Alpheratz B is 3.63 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: 203 % R Sun
| 20.2 R Jupiter
+
Star size
Radius of the star Alpheratz B is 2.03 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: 7935 K | 1.37 T Sun
+
Star temperature
Surface temperature of Alpheratz B is 7935 K, which is 137 % 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
luminosity icon
Luminosity: 14.79 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

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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Alpheratz system structure

 Alpheratz A
Alpheratz B

More about Alpheratz

       Alpheratz 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
Alpheratz, Sirrah, Sirah, H 5 32A, α And, Alpha Andromedae, Alpha And, δ Pegasi, δ Peg, Delta Pegasi, Delta Peg, 21 Andromedae, 21 And, BD+28°4, FK5 1, GC 127, HD 358, HIP 677, HR 15, SAO 73765, PPM 89441, ADS 94 A, CCDM J00083+2905A, WDS 00084+2905A/Aa, LTT 10039, NLTT 346
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Frequently Asked Questions

How far is the Alpheratz system from the Sun?

The Alpheratz system is 97 light years or 29.7 parsecs from the Sun.

What galaxy is the Alpheratz star in?

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

How many stars are in the Alpheratz system?

The Alpheratz system contains 2 stars.

What type of star is the Alpheratz?

The primary in the Alpheratz system is a Subgiant star.

What temperature is the Alpheratz?

The primary in the Alpheratz system has an effective temperature of K ( °C). Find out more about the temperature of stars in Stellar guide
Closest stars

 LP 292-63
 - 5 ly

PW Andromedae
 - 6.7 ly

LSPM J0018+2603
 - 7.5 ly

BD+32 4747
 - 8.5 ly

HD 222935
 - 8.6 ly
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