Iota Boötis is a 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...

 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....

 Boötes

Boötes

Boötes is a constellation in the northern sky, located between 0° and +60° declination, and 13 and 16 hours of right ascension on the celestial sphere. The name comes from the Greek Βοώτης, Boōtēs, meaning herdsman or plowman...

. It has the traditional name Asellus Secundus (Latin for "second donkey

Donkey

The donkey or ass, Equus africanus asinus, is a domesticated member of the Equidae or horse family. The wild ancestor of the donkey is the African Wild Ass, E...

 colt") and the Flamsteed designation

Flamsteed designation

Flamsteed designations for stars are similar to Bayer designations, except that they use numbers instead of Greek letters. Each star is assigned a number and the Latin genitive of the constellation it lies in...

 21 Boötis.

This star, along with the other Asselus (θ Boo

Theta Boötis

Theta Boötis is a star in the constellation Boötes. It has the traditional name Asellus Primus and the Flamsteed designation 23 Boötis....

 and κ Boo

Kappa Boötis

Kappa Boötis is a star system in the constellation Boötes. It has the traditional name Asellus Tertius and the Flamsteed designation 17 Boötis...

) and λ Boo

Lambda Boötis

Lambda Boötis is a star in the constellation Boötes.Lambda Boötis is a white A-type main sequence dwarf with an apparent magnitude of +4.18. It is approximately 97.1 light-years from Earth. Lambda Boötis is the prototype of a group of rare stars known as Lambda Boötis stars, all of which are...

, were Al Aulād al Dhiʼbah (ألعولد ألذعب - al aulād al dhiʼb), "the Whelps of the Hyenas"..

In Chinese

Chinese language

The Chinese language is a language or language family consisting of varieties which are mutually intelligible to varying degrees. Originally the indigenous languages spoken by the Han Chinese in China, it forms one of the branches of Sino-Tibetan family of languages...

, , meaning Celestial Spear

Purple Forbidden enclosure

The Purple Forbidden enclosure is one of the San Yuan or Three enclosures. Stars and constellations of this group lie near the north celestial pole and visible all year from temperate latitudes in the Northern Hemisphere.-Asterisms:The asterisms are :...

, refers to an asterism consisting of ι Boötis, κ² Boötis

Kappa Boötis

Kappa Boötis is a star system in the constellation Boötes. It has the traditional name Asellus Tertius and the Flamsteed designation 17 Boötis...

 and θ Boötis

Theta Boötis

Theta Boötis is a star in the constellation Boötes. It has the traditional name Asellus Primus and the Flamsteed designation 23 Boötis....

. Consequently, ι Boötis itself is known as

Iota Boötis is a 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...

, with components at an angular distance

Angular distance

In mathematics and all natural sciences , the angular distance between two point objects, as observed from a location different from either of these objects, is the size of the angle between the two directions originating from...

 of 38.6 arcseconds, easily separated with binoculars. It is approximately 97 light years from Earth.

Components

The primary component, Iota Boötis A, a spectroscopic binary, is a white A-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...

 main sequence dwarf

Main sequence

The main sequence is a continuous and distinctive band of stars that appears on plots of stellar color versus brightness. These color-magnitude plots are known as Hertzsprung–Russell diagrams after their co-developers, Ejnar Hertzsprung and Henry Norris Russell...

 with a mean 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 +4.75. It is classified as a Delta Scuti type

Delta Scuti variable

A Delta Scuti variable is a variable star which exhibits variations in its luminosity due to both radial and non-radial pulsations of the star's surface. Typical brightness fluctuations are from 0.003 to 0.9 magnitudes in V over a period of a few hours, although the amplitude and period of the...

 variable star

Variable star

A star is classified as variable if its apparent magnitude as seen from Earth changes over time, whether the changes are due to variations in the star's actual luminosity, or to variations in the amount of the star's light that is blocked from reaching Earth...

and its brightness varies from magnitude +4.73 to +4.78. The companion, Iota Boötis B, is a magnitude +8.27 star belonging to spectral class A2.