Sigma Ursae Majoris
Encyclopedia
The Bayer designation
Sigma Ursae Majoris (σ UMa, σ Ursae Majoris) is shared by two star system
s in the constellation
Ursa Major
:
They are separated by 0.33° in the sky.
The two stars, Sigma¹ and Sigma² together, are considered an optical double star
. They are not a binary star
, in that they are not gravitationally linked, but they are close to each other as seen in the sky.
Bayer designation
A Bayer designation is a stellar designation in which a specific star is identified by a Greek letter, followed by the genitive form of its parent constellation's Latin name...
Sigma Ursae Majoris (σ UMa, σ Ursae Majoris) is shared by two star system
Star system
A star system or stellar system is a small number of stars which orbit each other, bound by gravitational attraction. A large number of stars bound by gravitation is generally called a star cluster or galaxy, although, broadly speaking, they are also star systems.-Binary star systems:A stellar...
s in the constellation
Constellation
In modern astronomy, a constellation is an internationally defined area of the celestial sphere. These areas are grouped around asterisms, patterns formed by prominent stars within apparent proximity to one another on Earth's night sky....
Ursa Major
Ursa Major
Ursa Major , also known as the Great Bear, is a constellation visible throughout the year in most of the northern hemisphere. It can best be seen in April...
:
- Sigma¹ Ursae MajorisSigma¹ Ursae MajorisSigma¹ Ursae Majoris is an orange K-type giant with an apparent magnitude of +5.15. It is approximately 500 light years from Earth....
(11 Ursae Majoris) - Sigma² Ursae MajorisSigma² Ursae MajorisSigma² Ursae Majoris is a binary star approximately 66.7 light years from Earth. The primary component, Sigma² Ursae Majoris A, is a yellow-white F-type subgiant with an apparent magnitude of +4.85. The companion, Sigma² Ursae Majoris B, is an orange K-type main sequence dwarf with an apparent...
(13 Ursae Majoris)
They are separated by 0.33° in the sky.
The two stars, Sigma¹ and Sigma² together, are considered an optical double star
Double star
In observational astronomy, a double star is a pair of stars that appear close to each other in the sky as seen from Earth when viewed through an optical telescope. This can happen either because the pair forms a binary star, i.e...
. They are not a binary star
Binary star
A binary star is a star system consisting of two stars orbiting around their common center of mass. The brighter star is called the primary and the other is its companion star, comes, or secondary...
, in that they are not gravitationally linked, but they are close to each other as seen in the sky.