Kappa Herculis (κ Herculis, abbreviated Kappa Her, κ Her) is an optical

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 bi ...

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 ...

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 ...

. The two components, Kappa Herculis A (Marsic , the traditional name of the system) and B, were 27.3 arc seconds apart in 2000. Based on

parallax Parallax is a displacement or difference in the apparent position of an object viewed along two different lines of sight and is measured by the angle or semi-angle of inclination between those two lines. Due to foreshortening, nearby objects ...

measurements from 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 of celestial obj ...

mission, κ Her A is about 113

parsec The parsec (symbol: pc) is a unit of length used to measure the large distances to astronomical objects outside the Solar System, approximately equal to or (au), i.e. . The parsec unit is obtained by the use of parallax and trigonometry, and ...

s (370

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 the Sun and κ Her B is 600 parsecs (2,000 light-years); more recent parallax measurements suggest that B is around 5% more distant than A. A faint third component Kappa Herculis C is just over 1

arc-minute 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 ...

away. It is at the same distance as κ Her A and has an almost-identical space motion. The star 8 Herculis forms a

naked eye Naked eye, also called bare eye or unaided eye, is the practice of engaging in visual perception unaided by a magnifying, light-collecting optical instrument, such as a telescope or microscope, or eye protection. Vision corrected to normal ...

pair with Kappa Herculis away.

Nomenclature

κ Herculis ( Latinised to ''Kappa Herculis'') is the system's

Bayer designation A Bayer designation is a stellar designation in which a specific star is identified by a Greek or Latin letter followed by the genitive form of its parent constellation's Latin name. The original list of Bayer designations contained 1,564 stars. ...

. The designations of the components as ''Kappa Herculis A'', ''B'' and ''C'' derive from the convention used by the Washington Multiplicity Catalog (WMC) for

multiple star system A star system or stellar system is a small number of stars that orbit each other, bound by gravitational attraction. A large group of stars bound by gravitation is generally called a '' star cluster'' or '' galaxy'', although, broadly speaki ...

s, and adopted by the

International Astronomical Union The International Astronomical Union (IAU; french: link=yes, Union astronomique internationale, UAI) is a nongovernmental organisation with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreac ...

(IAU). The system bore the traditional names of "Marsic", "Marfik" or "Marfak", all of which come from the

Arabic Arabic (, ' ; , ' or ) is a Semitic languages, Semitic language spoken primarily across the Arab world.Semitic languages: an international handbook / edited by Stefan Weninger; in collaboration with Geoffrey Khan, Michael P. Streck, Janet C ...

لمرفق ''Al-Mirfaq'' meaning "the elbow", a name (or some derivative of which) it shared with

Lambda Ophiuchi λ Ophiuchi, Latinized as Lambda Ophiuchi, is a triple star system in the equatorial constellation of Ophiuchus. It has the traditional name Marfik , which now applies exclusively to the primary component. The system is visible to the ...

. The

Working Group on Star Names The International Astronomical Union (IAU) established a Working Group on Star Names (WGSN) in May 2016 to catalog and standardize proper names for stars for the international astronomical community. It operates under Division C – Education ...

(WGSN) approved the name ''Marsic'' for the component Kappa Herculis A on February 1, 2017, and ''Marfik'' for the primary component of Lambda Ophiuchi on September 12, 2016, and they are both now so included in the List of IAU-approved Star Names. 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 '' Right Wall of Heavenly Market Enclosure'', refers to an asterism which represents eleven old states in China and marks the right borderline of the enclosure, consisting of Kappa Herculis,

Beta Herculis Beta Herculis (β Herculis, abbreviated Beta Her, β Her), formally named Kornephoros , or Rutilicus, is a binary star and the brightest star in the northern constellation of Hercules at a base apparent visual magni ...

Gamma Herculis Gamma Herculis, Latinized from γ Herculis, is a magnitude 3.74 binary star system in the northern constellation of Hercules. Properties This is known to be a spectroscopic binary system, although there is no information about the seco ...

Gamma Serpentis Gamma Serpentis (γ Serpentis, γ Ser) is a star in the equatorial constellation Serpens, in the part of the constellation that represents the serpent's head (Serpens Caput). It has an apparent visual magnitude +3.85, which means it is vi ...

Beta Serpentis Beta Serpentis, Latinized from β Serpentis, is a binary star system in the constellation Serpens, in its head (Serpens Caput). It is visible to the naked eye with a combined apparent visual magnitude of +3.65. Based upon an annual par ...

Delta Serpentis Delta Serpentis, Latinized from δ Serpentis, is a binary star system in the constellation Serpens, in its head (Serpens Caput). The light from the two stars in the system give a combined apparent magnitude of +3.80, which is bright enou ...

Alpha Serpentis Alpha Serpentis or α Serpentis, formally named Unukalhai (), is a double star in the head (Serpens Caput) of the equatorial constellation of Serpens. With an apparent visual magnitude of 2.6, this star is the brightest in the constell ...

Epsilon Serpentis Epsilon Serpentis, Latinized from ε Serpentis, is a single, white-hued star in the constellation Serpens, in its head (Serpens Caput). It is visible to the naked eye with an apparent visual magnitude of +3.69. Based upon an annual parall ...

Delta Ophiuchi Delta Ophiuchi (δ Ophiuchi, abbreviated Delta Oph, δ Oph), formally named Yed Prior , is a star in the constellation of Ophiuchus. It forms a naked-eye optical double with Epsilon Ophiuchi (named ''Yed Posterior''). The apparent visual ...

Epsilon Ophiuchi Epsilon Ophiuchi or ε Ophiuchi, formally named Yed Posterior (), is a red giant star in the constellation of Ophiuchus. Located less than five degrees south of the celestial equator in the eastern part of the constellation, it forms a ...

and

Zeta Ophiuchi Zeta Ophiuchi (ζ Oph, ζ Ophiuchi) is a single star located in the constellation of Ophiuchus. It has an apparent visual magnitude of 2.6, making it the third-brightest star in the constellation. Parallax measurements give an estimate ...

. Consequently, the

Chinese name Chinese names or Chinese personal names are names used by individuals from Greater China and other parts of the Chinese-speaking world throughout East and Southeast Asia (ESEA). In addition, many names used in Japan, Korea and Vietnam are often a ...

for Kappa Herculis itself is (, en, the Third Star of Right Wall of Heavenly Market Enclosure), representing the state of Jin (晉) (or Tsin), together with 36 Capricorni in '' Twelve States'' (asterism).

Properties

Kappa Herculis A is a

giant star A giant star is a star with substantially larger radius and luminosity than a main sequence, main-sequence (or ''dwarf'') star of the same effective temperature, surface temperature.Giant star, entry in ''Astronomy Encyclopedia'', ed. Patrick Moo ...

with

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 grati ...

G8III. With a mass of and radius that is , the star boasts a

bolometric luminosity Luminosity is an absolute measure of radiated electromagnetic power (light), the radiant power emitted by a light-emitting object over time. In astronomy, luminosity is the total amount of electromagnetic energy emitted per unit of time by a s ...

that is . Its slightly companion is cooler and about a third of the luminosity. Kappa Herculis is a suspected

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 ...

with a reported magnitude range of 4.70 to 5.02.

References

External links

*Jim Kaler's Stars, University of Illinois
MARSIC (Kappa Herculis)
*Hercules constellation map showing

{{Stars of Hercules Hercules (constellation) Herculis, Kappa Marsic G-type giants Herculis, 007 079043 145001 6008 BD+77 2964 Suspected variables