Delta 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 northern

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 ...

, forming the easternmost member of the constellation's kite-shaped asterism of brighter stars. 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 δ Boötis, and abbreviated Delta Boo or δ Boo. Based upon

parallax Parallax is a displacement or difference in the apparent position of an object viewed along two different sightline, lines of sight and is measured by the angle or half-angle of inclination between those two lines. Due to perspective (graphica ...

measurements, it is located at a distance of approximately from the

Earth Earth is the third planet from the Sun and the only astronomical object known to Planetary habitability, harbor life. This is enabled by Earth being an ocean world, the only one in the Solar System sustaining liquid surface water. Almost all ...

. The

apparent visual magnitude Apparent magnitude () is a measure of the brightness of a star, astronomical object or other celestial objects like artificial satellites. Its value depends on its intrinsic luminosity, its distance, and any extinction of the object's light ca ...

of this star is 3.5, making it visible to the

naked eye Naked eye, also called bare eye or unaided eye, is the practice of engaging in visual perception unaided by a magnification, magnifying, Optical telescope#Light-gathering power, light-collecting optical instrument, such as a telescope or microsc ...

even during a Full Moon. The magnitude 7.81 companion can be viewed in binoculars or a small telescope.

Properties

This system consists of a pair of stars located in physical proximity to each other and sharing a similar motion through space, suggesting that they may form a

binary star 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 ...

system. Based upon their angular separation and their distance, they have a

projected separation This glossary of astronomy is a list of definitions of terms and concepts relevant to astronomy and cosmology, their sub-disciplines, and related fields. Astronomy is concerned with the study of celestial objects and phenomena that originate outs ...

of 3,800

Astronomical Unit The astronomical unit (symbol: au or AU) is a unit of length defined to be exactly equal to . Historically, the astronomical unit was conceived as the average Earth-Sun distance (the average of Earth's aphelion and perihelion), before its m ...

s (AU). If they are gravitationally bound to each other, the

orbital period The orbital period (also revolution period) is the amount of time a given astronomical object takes to complete one orbit around another object. In astronomy, it usually applies to planets or asteroids orbiting the Sun, moons orbiting planets ...

of the system would be at least 120,000 years. The brighter member of the pair has a

stellar classification In astronomy, stellar classification is the classification of stars based on their stellar spectrum, spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a Prism (optics), prism or diffraction gratin ...

of G8 III, indicating that it has exhausted the supply of hydrogen at its core and

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 ...

into a

giant star A giant star has a substantially larger radius and luminosity than a main-sequence (or ''dwarf'') star of the same surface temperature. They lie above the main sequence (luminosity class V in the Yerkes spectral classification) on the Hertzsp ...

. It now has a radius more than eleven times the radius of the Sun. Compared to the

Sun The Sun is the star at the centre of the Solar System. It is a massive, nearly perfect sphere of hot plasma, heated to incandescence by nuclear fusion reactions in its core, radiating the energy from its surface mainly as visible light a ...

, this star appears deficient in elements other than hydrogen and helium—what astronomers term the star's

metallicity In astronomy, metallicity is the Abundance of the chemical elements, abundance of Chemical element, elements present in an object that are heavier than hydrogen and helium. Most of the normal currently detectable (i.e. non-Dark matter, dark) matt ...

. The outer envelope of this star has 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 4,810 K, which is what gives it the characteristic yellow hue of a

G-type star 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 the ...

. The secondary component has a stellar classification of G0 V, which suggests it is a

main sequence In astronomy, the main sequence is a classification of stars which appear on plots of stellar color index, color versus absolute magnitude, brightness as a continuous and distinctive band. Stars on this band are known as main-sequence stars or d ...

star that may be similar in physical properties to the Sun. The apparent visual magnitude of this star is 7.81, making it much less luminous than the primary component.

Nomenclature

This star is sometimes called Princeps , meaning ''prince'' or ''prime'' in

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 ...

. The origin of this name is unclear, although it usually appears in an

astrological Astrology is a range of divinatory practices, recognized as pseudoscientific since the 18th century, that propose that information about human affairs and terrestrial events may be discerned by studying the apparent positions of celesti ...

context. 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 '' Seven Excellencies'', refers to an asterism consisting of δ Boötis, 42 Herculis, τ Herculis, φ Herculis, χ Herculis, ν¹ Boötis and μ¹ Boötis. 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 δ Boötis itself is (, .)AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 6 月 26 日

References

External links

HR 5681

CCDM J15156+3319

Image Delta Boötis
{{DEFAULTSORT:Delta Bootis G-type giants G-type main-sequence stars Binary stars Boötes Bootis, Delta 5681 Durchmusterung objects Bootis, 49 135722 074666