Nu Ophiuchi (ν Oph, ν Ophiuchi) is a

star A star is a luminous spheroid of plasma (physics), plasma held together by Self-gravitation, self-gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked eye at night sk ...

in the equatorial

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 ...

Ophiuchus Ophiuchus () is a large constellation straddling the celestial equator. Its name comes from the Ancient Greek (), meaning "serpent-bearer", and it is commonly represented as a man grasping a snake. The serpent is represented by the constellati ...

. 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 ...

is +3.3, making it one of the brighter members of this constellation. 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 made by 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 ...

satellite, this star is located at a distance of about .

Properties

Nu Ophiuchi has about three times the mass of the Sun and is roughly 450 million years old. 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 the star matches 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 K0 IIIa, indicating it is 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 ...

that 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 ...

away from the

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 ...

of stars. Unusually, it displays an anomalously low abundance of

cyanogen Cyanogen is the chemical compound with the chemical formula, formula . Its structure is . The simplest stable carbon nitride, it is a Transparency and translucency, colorless and highly toxic gas with a pungency, pungent odor. The molecule is a ...

for a star of its type. The star's outer envelope has expanded to around 14 times the Sun's radius and now radiates with a luminosity 108 times that of the Sun. This energy is emitted from its outer envelope 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 5,000 K, giving it the cool, orange hue of a

K-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 ...

Companions

This is not 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 in the sense of having a gravitationally-bound stellar companion. However, in November 2003, a

brown dwarf Brown dwarfs are substellar objects that have more mass than the biggest gas giant planets, but less than the least massive main sequence, main-sequence stars. Their mass is approximately 13 to 80 Jupiter mass, times that of Jupiter ()not big en ...

companion called Nu Ophiuchi b was discovered. This sub-stellar companion has at least 21.9 times the

mass of Jupiter The Jupiter mass, also called Jovian mass, is the units of mass, unit of mass equal to the total mass of the planet Jupiter. This value may refer to the mass of the planet alone, or the mass of the entire Jovian system to include the moons of Jup ...

and takes 536 days (1.47 years) to complete an

orbit In celestial mechanics, an orbit (also known as orbital revolution) is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an ...

. A second brown dwarf companion was discovered in 2010, orbiting further from the star with a period of 3,169 days (8.68 years). These were confirmed in 2012. The two brown dwarfs are locked in a 1:6

orbital resonance In celestial mechanics, orbital resonance occurs when orbiting bodies exert regular, periodic gravitational influence on each other, usually because their orbital periods are related by a ratio of small integers. Most commonly, this relation ...

. This star is following an orbit through the galaxy that carries it between from the

Galactic Center The Galactic Center is the barycenter of the Milky Way and a corresponding point on the rotational axis of the galaxy. Its central massive object is a supermassive black hole of about 4 million solar masses, which is called Sagittarius A*, a ...

. As a probable member of the Milky Way's thin disk population, it has a low

orbital inclination Orbital inclination measures the tilt of an object's orbit around a celestial body. It is expressed as the angle between a reference plane and the orbital plane or axis of direction of the orbiting object. For a satellite orbiting the Earth ...

that carries it no more than about above the

galactic plane The galactic plane is the plane (geometry), plane on which the majority of a disk-shaped galaxy's mass lies. The directions perpendicular to the galactic plane point to the galactic poles. In actual usage, the terms ''galactic plane'' and ''galac ...

Naming

This star is sometimes called by the name Sinistra, meaning ''left side'' 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 ...

, although authors like Jim Kaler recommend not using this name, and instead stick to the Bayer designation only (Nu Ophiuchi). In

China China, officially the People's Republic of China (PRC), is a country in East Asia. With population of China, a population exceeding 1.4 billion, it is the list of countries by population (United Nations), second-most populous country after ...

, the star is part of (), meaning '' Left Wall of Heavenly Market Enclosure.'' The stars in this group include ν Ophiuchi, δ Herculis, λ Herculis, μ 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, ξ Serpentis and

η Ophiuchi Eta Ophiuchi (η Ophiuchi, abbreviated Eta Oph, η Oph) is a binary star in the constellation of Ophiuchus. With a combined apparent magnitude of +2.43, it is the second-brightest of the constellation and one of the brightest stars in th ...

. Consequently, ν Ophiuchi itself is known as (, ), and together with ζ Capricorni represents the state Yan (燕) in the '' Twelve States'' constellation.

References

{{DEFAULTSORT:Nu Ophiuchi Ophiuchi, Nu Ophiuchus K-type giants Brown dwarfs Planetary systems with two confirmed planets Ophiuchi, 64 088048 6698 163917 Durchmusterung objects J17590160-0946249

Properties

Companions

Naming

See also

References