Iota Boötis (ι Boo, ι Boötis) is a member of a binary star system in the

constellation A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The origins of the e ...

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 la, Boōtēs, which comes from grc-gre, Βοώτης, Boṓtēs ...

, approximately 96

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 Earth. It has the traditional name Asellus Secundus (

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

for "second

donkey The domestic donkey is a hoofed mammal in the family Equidae, the same family as the horse. It derives from the African wild ass, ''Equus africanus'', and may be classified either as a subspecies thereof, ''Equus africanus asinus'', or as a ...

colt") and the Flamsteed designation 21 Boötis. The companion is HD 234121, a K0

main sequence In astronomy, 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 Her ...

star.

Components

Iota Boötis has a companion at an angular distance of 38.6

arcseconds 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 na ...

, easily separated with binoculars. The primary component is a white A-type

main-sequence In astronomy, 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 Hert ...

dwarf with a mean

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 +4.75. It is classified as a Delta Scuti-type

variable star A variable star is a star whose brightness as seen from Earth (its apparent magnitude) changes with time. This variation may be caused by a change in emitted light or by something partly blocking the light, so variable stars are classified as ...

and its brightness varies from magnitude +4.73 to +4.78 with a stable period of 38 minutes. The companion, HD 234121, is a magnitude 7.3 main-sequence star belonging to spectral class K0V. It is separated from ι Boo by . HD 234121 has a mass of , a luminosity of , a temperature of , and a radius of . The

Washington Double Star Catalog The Washington Double Star Catalog, or WDS, is a catalog of double stars, maintained at the United States Naval Observatory. The catalog contains positions, magnitudes, proper motions and spectral types and has entries for (as of June 2017) 141,7 ...

lists a third component, a 14th-magnitude star at 90 arcseconds, but it is an unrelated background star.

Nomenclature

This star, along with the other ''Aselli'' ( θ Boo and κ Boo) and λ Boo, were ''Aulād al Dhiʼbah'' (أولاد الضّباع - ''awlād al-ḍibā‘), "the Whelps of the Hyenas". In

Chinese Chinese can refer to: * Something related to China * Chinese people, people of Chinese nationality, citizenship, and/or ethnicity **''Zhonghua minzu'', the supra-ethnic concept of the Chinese nation ** List of ethnic groups in China, people of va ...

, (), meaning '' Celestial Spear'', refers to an asterism consisting of ι Boötis, κ² Boötis and θ Boötis. Consequently, the Chinese name for ι Boötis itself is (, en, the Second Star of Celestial Spear).

References

External links

HR 5350

CCDM J14162+5122

Image Iota Boötis

{{DEFAULTSORT:Iota Bootis 125161 069713 Bootis, Iota Boötes Delta Scuti variables Bootis, 21 Spectroscopic binaries Triple star systems A-type main-sequence stars Asellus Secundus K-type main-sequence stars 5350 BD+52 1784