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Iota Ursae Majoris
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Star Iota Ursae Majoris

Triple star system Iota Ursae Majoris is located 48 light years away from the Sun. It is a system with 3 stars. For now, there are no known exoplanets in this star system.
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Sun distance
48 light years
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Iota Ursae Majoris A

Subgiant, Spectroscopic binary
Spectral class: F0IV-V

Location +

Ascension iconRight ascension: 8h 59m 11.753s
Declination iconDeclination: 48° 2' 27.137'' (northern hemisphere)
Parallax iconParallax: 68.001
Distance iconSun distance: 47.963 ly | 14.7 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: 170 % M Sun
| 1781 M Jupiter
+
Star mass
Mass of the star Iota Ursae Majoris A is 1.7 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: 240 % R Sun
| 23.8 R Jupiter
(estimate)
+
Star size
Radius of the star Iota Ursae Majoris A is not known. Its estimated value based on other similar stars is about 240 % 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 iconTemperature: 7100 K
 (estimate)
+
Star temperature
Surface temperature of Iota Ursae Majoris A is estimated to be 7056 K, which is 123 % 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: 9.87 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): 3.1
Magnitude iconAbsolute magnitude (V): 2.3
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

Iota Ursae Majoris B

Red dwarf, , Spectroscopic binary
Spectral class: M3V

Basic characteristic

icon weight
Mass: 35 % M Sun
| 367 M Jupiter
+
Star mass
Mass of the star Iota Ursae Majoris B is 1.7 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: 40 % R Sun
| 4 R Jupiter
(estimate)
+
Star size
Radius of the star Iota Ursae Majoris B is not known. Its estimated value based on other similar stars is about 40 % 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 iconTemperature: 3400 K
 (estimate)
+
Star temperature
Surface temperature of Iota Ursae Majoris B is estimated to be 3433 K, which is 59 % 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

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

Iota Ursae Majoris C

Red dwarf, , , Spectroscopic binary
Spectral class: M4V

Basic characteristic

icon weight
Mass: 30 % M Sun
| 314 M Jupiter
+
Star mass
Mass of the star Iota Ursae Majoris C is 0.35 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: 30 % R Sun
| 3.3 R Jupiter
(estimate)
+
Star size
Radius of the star Iota Ursae Majoris C is not known. Its estimated value based on other similar stars is about 30 % 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 iconTemperature: 3300 K
 (estimate)
+
Star temperature
Surface temperature of Iota Ursae Majoris C is estimated to be 3300 K, which is 57 % 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

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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Iota Ursae Majoris system structure

 Iota Ursae Majoris A
Iota Ursae Majoris B
Iota Ursae Majoris C

More about Iota Ursae Majoris

       Iota Ursae Majoris 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
iot UMa, iot UMa A, Talitha, Talitha Borealis, Alphikra Borealis, ι Ursae Majoris, ι UMa, Iota UMa, 9 Ursae Majoris, BD+48 1707, FK5 335, Gliese 331, GJ 331, HD 76644, HIP 44127, HR 3569, SAO 42630, WDS J08592+4803A,BC, Gaia EDR3 1014058103758571520
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Frequently Asked Questions

How far is the Iota Ursae Majoris system from the Sun?

The Iota Ursae Majoris system is 48 light years or 14.7 parsecs from the Sun.

What galaxy is the Iota Ursae Majoris star in?

The Iota Ursae Majoris is in the Milky Way galaxy just like the Sun.

How many stars are in the Iota Ursae Majoris system?

The Iota Ursae Majoris system contains 3 stars.

What type of star is the Iota Ursae Majoris?

The primary in the Iota Ursae Majoris system is a Subgiant star.

What temperature is the Iota Ursae Majoris?

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

 G 194-47
 - 6.1 ly

Theta Ursae Majoris
 1.4 M☉ 6.5 ly

2MASS J08300825+4828482
 - 6.5 ly

10 Ursae Majoris
 1.4 M☉ 7.1 ly

2MASS J0857+5708
 - 8 ly
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27. 10. 2026
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