Eta Ursae Minoris, Latinized from η Ursae Minoris, is a yellow-white hued

star A star is an astronomical object comprising a luminous spheroid of plasma held together by its gravity. The nearest star to Earth is the Sun. Many other stars are visible to the naked eye at night, but their immense distances from Earth make ...

in the northern

circumpolar constellation A circumpolar star is a star that, as viewed from a given latitude on Earth, never sets below the horizon due to its apparent proximity to one of the celestial poles. Circumpolar stars are therefore visible from said location toward the nearest po ...

Ursa Minor Ursa Minor (Latin: 'Lesser Bear', contrasting with Ursa Major), also known as the Little Bear, is a constellation located in the far northern celestial hemisphere, northern sky. As with the Great Bear, the tail of the Little Bear may also be see ...

. This is an

F-type main-sequence star An F-type main-sequence star (F V) is a main-sequence, hydrogen-fusing star of spectral type F and luminosity class V. These stars have from 1.0 to 1.4 times the mass of the Sun and surface temperatures between 6,000 and 7,600 K.Tables VI ...

stellar classification In astronomy, stellar classification is the classification of stars based on their spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a prism or diffraction grating into a spectrum exhibiting t ...

F5 V with an

apparent magnitude Apparent magnitude () is a measure of the brightness of a star or other astronomical object observed from Earth. An object's apparent magnitude depends on its intrinsic luminosity, its distance from Earth, and any extinction of the object's li ...

of +4.95, making it faintly visible to the naked eye. Based upon an annual parallax shift of 33.4 mas as seen from the Earth, it is located 98

light year A light-year, alternatively spelled light year, is a large unit of length used to express astronomical distances and is equivalent to about 9.46 trillion kilometers (), or 5.88 trillion miles ().One trillion here is taken to be 1012 ...

s from the

Sun The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared rad ...

. The star is moving closer to the Sun with a

radial velocity The radial velocity or line-of-sight velocity, also known as radial speed or range rate, of a target with respect to an observer is the rate of change of the distance or range between the two points. It is equivalent to the vector projection ...

of −11 km/s, and is traversing the sky with a relatively high

proper motion Proper motion is the astrometric measure of the observed changes in the apparent places of stars or other celestial objects in the sky, as seen from the center of mass of the Solar System, compared to the abstract background of the more dista ...

of 0.271

arc second A minute of arc, arcminute (arcmin), arc minute, or minute arc, denoted by the symbol , is a unit of angular measurement equal to of one degree. Since one degree is of a turn (or complete rotation), one minute of arc is of a turn. The nau ...

s per year. Eta Ursae Minoris is about one billion years old and has an estimated 1.35 times the

mass of the Sun The solar mass () is a standard unit of mass in astronomy, equal to approximately . It is often used to indicate the masses of other stars, as well as stellar clusters, nebulae, galaxies and black holes. It is approximately equal to the mass of ...

. It has a high rate of spin with a

projected rotational velocity Stellar rotation is the angular motion of a star about its axis. The rate of rotation can be measured from the spectrum of the star, or by timing the movements of active features on the surface. The rotation of a star produces an equatorial bulge ...

of 84.8 km/s. These coordinates mark a source of X-ray emission with a luminosity of . Eta Ursae Minoris may form a wide binary system with a magnitude 15.3 companion star, located at an

angular separation Angular distance \theta (also known as angular separation, apparent distance, or apparent separation) is the angle between the two sightlines, or between two point objects as viewed from an observer. Angular distance appears in mathematics (in pa ...

of 228.5

s. In some Arabic star charts it is labeled انور الفرقدين ''ʼanwar al-farqadayn'', "the brighter of the two calves", and paired with

ζ Ursae Minoris Zeta Ursae Minoris, which is Romanization of Greek, Latinized from ζ Ursae Minoris, is a single star in the northern circumpolar constellation of Ursa Minor, forming the northernmost part of the bowl in this "little dipper" Asterism (ast ...

as اخفي الفرقدين ''akhfā al-farkadain'' "the dimmer of the two calves". The names may originally refer to a pair of Ibexes, and are more properly applied to β UMi and γ UMi respectively, the brighter two stars in the rectangle of Ursa Minor.

References

{{DEFAULTSORT:Eta Ursae Minoris F-type main-sequence stars Ursae Minoris, Eta Ursa Minor (constellation) Durchmusterung objects Ursae Minoris, 21 148048 079822 6116