Mu Herculis (μ Herculis) is a nearby quadruple

star system A star system or stellar system is a small number of stars that orbit each other, bound by gravity, gravitational attraction. It may sometimes be used to refer to a single star. A large group of stars bound by gravitation is generally calle ...

about 27.1

light year A light-year, alternatively spelled light year (ly or lyr), is a unit of length used to express astronomical distance, astronomical distances and is equal to exactly , which is approximately 9.46 trillion km or 5.88 trillion mi. As defined by t ...

s from Earth 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 ...

Hercules Hercules (, ) is the Roman equivalent of the Greek divine hero Heracles, son of Jupiter and the mortal Alcmena. In classical mythology, Hercules is famous for his strength and for his numerous far-ranging adventures. The Romans adapted the Gr ...

. Its main star, Mu Herculis A is fairly similar 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 ...

although more highly

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 ...

with 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 G5 IV. Since 1943, the

spectrum A spectrum (: spectra or spectrums) is a set of related ideas, objects, or properties whose features overlap such that they blend to form a continuum. The word ''spectrum'' was first used scientifically in optics to describe the rainbow of co ...

of this star has served as one of the stable anchor points by which other stars are classified. Its mass is about 1.1 times that of the Sun, and it is beginning to expand to become a giant.

Etymology

In the catalogue of stars in the ''Calendarium of Al Achsasi Al Mouakket'', this star was designated ''Marfak Al Jathih Al Aisr'', which was translated into

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 ...

as ''Cubitum Sinistrum Ingeniculi'', meaning ''the left elbow of kneeling man''. In Chinese, (), the '' Left Wall of Heavenly Market Enclosure'', refers to an asterism which represents eleven old states in China, marking the left borderline of the enclosure, consisting of μ Herculis, δ Herculis, λ Herculis, ο Herculis, 112 Herculis,

ζ Aquilae Zeta Aquilae is a binary star system in the equatorial constellation of Aquila (constellation), Aquila. Its name is a Bayer designation that is Romanization of Greek, Latinized from ζ Aquilae, and abbreviated Zeta Aql or ζ Aql. This sys ...

, θ¹ Serpentis, η Serpentis, ν Ophiuchi, ξ Serpentis and η Ophiuchi. 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 μ Herculis itself is (, ), represent ''Jiuhe'' (九河, lit. meaning ''nine rivers''), possibly for

Jiujiang Jiujiang, formerly transliterated Kiukiang and Kew-Keang, is a prefecture-level city located on the southern shores of the Yangtze River in northwest Jiangxi Province in the People's Republic of China. It is the second-largest prefecture-level ...

, the prefecture-level city in Jiangxi, China, which is the same literally meaning with ''Jiuhe''. From this Chinese title, the name ''Kew Ho'' appeared.Star Name - R.H. Allen p. 238
/ref>

Star system

Mu Herculis is a quadruple star system. The brightest star is a well-studied G-type

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 ...

, whose parameters are precisely determined from

asteroseismology Asteroseismology is the study of oscillations in stars. Stars have many Resonance, resonant modes and frequencies, and the path of sound waves passing through a star depends on the local speed of sound, which in turn depends on local temperature a ...

. It was believed to be a close binary with a low-mass stellar or a large substellar companion. This was confirmed when low-mass companion was resolved using near-infrared spectroscopy. The companion star is a

red dwarf A red dwarf is the smallest kind of star on the main sequence. Red dwarfs are by far the most common type of fusing star in the Milky Way, at least in the neighborhood of the Sun. However, due to their low luminosity, individual red dwarfs are ...

with a

spectral type 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 ...

of M4V and a mass of . This pair is also known as Mu¹ Herculis. The secondary component, also known as Mu² Herculis, consists of a pair of stars that orbit about each other with a period of about 43 years. Mu Herculis A and the binary pair B-C are separated by some 35 arcseconds. The stars B and C, which orbit each other, are separated from each other by 1.385 arcseconds, and have a slightly eccentric orbit, at 0.1796.

References

External links

*Jim Kaler's Stars, University of Illinois
MU HER (Mu Herculis)
*SolStation

{{DEFAULTSORT:Mu Herculis Hercules (constellation) 4 G-type subgiants M-type main-sequence stars Herculis, Mu Herculis, Mu Herculis, 086 086974 6623 0695 Durchmusterung objects 161797

Etymology

Star system

See also

References

External links