Theta Ursae Majoris (θ UMa, θ Ursae Majoris) is 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 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...

. It is approximately 45 light years

Light Years

Light Years is the seventh studio album by Australian recording artist Kylie Minogue. It was released on 25 September 2000 by Parlophone and Mushroom Records. The album's style was indicative of her return to "mainstream pop dance tunes"....

 from Earth

Earth

Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...

.

With τ, h

23 Ursae Majoris

23 Ursae Majoris, or 23 UMa, is a triple star in the constellation Ursa Major. Its main components, 23 UMa A and 23 UMa B, are approximately 75.5 light years from Earth....

, υ

Upsilon Ursae Majoris

Upsilon Ursae Majoris is a binary star in the constellation Ursa Major. It is approximately 115 light years from Earth....

, φ, e, and f, it composed the Arabic asterism

Asterism (astronomy)

In astronomy, an asterism is a pattern of stars recognized on Earth's night sky. It may form part of an official constellation, or be composed of stars from more than one. Like constellations, asterisms are in most cases composed of stars which, while they are visible in the same general direction,...

 Sarīr Banāt al-Na'sh, the Throne of the daughters of Na'sh, and al-Haud, the Pond, and formed Wan Chang （文昌）, the Literary Illumination, in Chinese astronomy

Chinese astronomy

Astronomy in China has a very long history, with historians considering that "they [the Chinese] were the most persistent and accurate observers of celestial phenomena anywhere in the world before the Arabs."...

.

The primary component, Theta Ursae Majoris A, is a yellow-white F-type

Stellar classification

In astronomy, stellar classification is a classification of stars based on their spectral characteristics. The spectral class of a star is a designated class of a star describing the ionization of its chromosphere, what atomic excitations are most prominent in the light, giving an objective measure...

 subgiant with an apparent magnitude

Apparent magnitude

The apparent magnitude of a celestial body is a measure of its brightness as seen by an observer on Earth, adjusted to the value it would have in the absence of the atmosphere...

 of +3.17. The 14th magnitude companion star is 4.1 arcseconds away from the primary.

Hunt for substellar objects

The McDonald Observatory

McDonald Observatory

The McDonald Observatory is an astronomical observatory located near the unincorporated community of Fort Davis in Jeff Davis County, Texas, United States. The facility is located on Mount Fowlkes and Mount Locke in the Davis Mountains of West Texas...

 team has set limits to the presence of one or more planets around Theta Ursae Majoris A with masses between 0.24 and 4.6 Jupiter masses and average separations spanning between 0.05 and 5.2 AU.

External links

• Theta Ursae Majoris by Professor Jim Kaler.