Kappa Boötis is a

double star In observational astronomy, a double star or visual double is a pair of stars that appear close to each other as viewed from Earth, especially with the aid of optical telescopes. This occurs because the pair either forms a binary star (i.e. a ...

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 first constellati ...

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 , which comes from 'herder, herdsman' or 'plowman' (literally, 'o ...

. Its name is a

Bayer designation A Bayer designation is a stellar designation in which a specific star is identified by a Greek alphabet, Greek or Latin letter followed by the genitive case, genitive form of its parent constellation's Latin name. The original list of Bayer design ...

that is Latinized from κ Boötis, and abbreviated Kappa Boo or κ Boo. This star has the traditional name Asellus Tertius, which is pronouced and is

Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

for "third

donkey The donkey or ass is a domesticated equine. It derives from the African wild ass, ''Equus africanus'', and may be classified either as a subspecies thereof, ''Equus africanus asinus'', or as a separate species, ''Equus asinus''. It was domes ...

colt". The components have an

angular separation Angular distance or angular separation is the measure of the angle between the orientation of two straight lines, rays, or vectors in three-dimensional space, or the central angle subtended by the radii through two points on a sphere. When t ...

of 13.5 arcsec; viewable in a small telescope. Kappa Boötis is approximately from Earth.

Properties

κ¹ Boötis is itself a double-lined

spectroscopic binary A binary star or binary star system is a system of two stars that are gravitationally bound to and in orbit around each other. Binary stars in the night sky that are seen as a single object to the naked eye are often resolved as separate stars us ...

star system. The primary component 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 ...

star of class F2V, while the secondary is half the mass and much fainter. κ² Boötis 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 systematically with time. This variation may be caused by a change in emitted light or by something partly blocking the light, so variable stars are ...

with a period of 1.08 hours Its brightness varies from magnitude +4.50 to +4.58. It is a slightly

evolved Evolution is the change in the heritable Phenotypic trait, characteristics of biological populations over successive generations. It occurs when evolutionary processes such as natural selection and genetic drift act on genetic variation, re ...

subgiant A subgiant is a star that is brighter than a normal main-sequence star of the same spectral class, but not as bright as giant stars. The term subgiant is applied both to a particular spectral luminosity class and to a stage in the evolution ...

, which indicates the hydrogen at its

core Core or cores may refer to: Science and technology * Core (anatomy), everything except the appendages * Core (laboratory), a highly specialized shared research resource * Core (manufacturing), used in casting and molding * Core (optical fiber ...

is all but exhausted. This star has more than double the mass of the Sun and nearly three times its girth. It has a high rate of spin, showing 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 bu ...

of 128 km/s. The star is radiating 28 times the luminosity of the Sun from its

photosphere The photosphere is a star's outer shell from which light is radiated. It extends into a star's surface until the plasma becomes opaque, equivalent to an optical depth of approximately , or equivalently, a depth from which 50% of light will esc ...

at an

effective temperature The effective temperature of a body such as a star or planet is the temperature of a black body that would emit the same total amount of electromagnetic radiation. Effective temperature is often used as an estimate of a body's surface temperature ...

of 7,760 K. A 17th-magnitude star nearly two

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

s away has been identified as a member of the multiple system with an estimated orbital period of 177,000 years. It is itself a close binary system consisting of two similar low-mass stars in a 234-year orbit.

Nomenclature

κ² Boötis, the brighter star of the pair, is also designated HD 124675, while κ¹ Boötis is HD 124674. The two stars share the

Bright Star Catalogue The Bright Star Catalogue, also known as the Yale Catalogue of Bright Stars, Yale Bright Star Catalogue, or just YBS, is a star catalogue that lists all stars of stellar magnitude 6.5 or brighter, which is roughly every star visible to the na ...

designation HR 5328 and the

Flamsteed designation A Flamsteed designation is a combination of a number and constellation name that uniquely identifies most naked eye stars in the 88 modern constellations, modern constellations visible from southern England. They are named after John Flamsteed, au ...

17 Boötis, but they have separate entries in the

Hipparcos ''Hipparcos'' was a scientific satellite of the European Space Agency (ESA), launched in 1989 and operated until 1993. It was the first space experiment devoted to precision astrometry, the accurate measurement of the positions and distances of ...

catalogue: HIP 69483 and HIP 69481 respectively. This star, along with the other ''Aselli'' (

θ Boo Theta (, ) uppercase Θ or ; lowercase θ or ; ''thē̂ta'' ; Modern: ''thī́ta'' ) is the eighth letter of the Greek alphabet, derived from the Phoenician letter Teth 𐤈. In the system of Greek numerals, it has a value of 9. Greek ...

and ι Boo) and λ Boo, were ''Aulād al Dhiʼbah'' (أولاد الضّباع - ''awlād al-ḍibā''), "the Whelps of the Hyenas". In

Chinese Chinese may refer to: * Something related to China * Chinese people, people identified with China, through nationality, citizenship, and/or ethnicity **Han Chinese, East Asian ethnic group native to China. **'' Zhonghua minzu'', the supra-ethnic ...

, (), meaning '' Celestial Spear'', refers to an asterism consisting of κ (actually κ²) Boötis,

ι Boötis Iota (; uppercase Ι, lowercase ι; ) is the ninth letter of the Greek alphabet. It was derived from the Phoenician letter Yodh. Letters that arose from this letter include the Latin I and J, the Cyrillic І (І, і), Yi (Ї, ї), and Je ...

and

θ Boötis Theta (, ) uppercase Θ or ; lowercase θ or ; ''thē̂ta'' ; Modern Greek, Modern: ''thī́ta'' ) is the eighth letter of the Greek alphabet, derived from the Phoenician alphabet, Phoenician letter Teth 𐤈. In the system of Greek numer ...

. Consequently, the

Chinese name Chinese may refer to: * Something related to China * Chinese people, people identified with China, through nationality, citizenship, and/or ethnicity **Han Chinese, East Asian ethnic group native to China. **'' Zhonghua minzu'', the supra-ethni ...

for κ Boötis itself is (, .)

References

External links

HR 5329

HR 5328

CCDM J14135+5147

Image Kappa Boötis
{{DEFAULTSORT:Kappa Bootis A-type subgiants F-type main-sequence stars Delta Scuti variables Double stars Binary stars Boötes Bootis, Kappa 5328 BD+52 1782 124674 5 069481 Boötis, 17 Asellus Tertius