Nu Ophiuchi (ν Oph, ν Ophiuchi) is a

star A star is an astronomical object comprising a luminous spheroid of plasma (physics), plasma held together by its gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked ...

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 origins of the e ...

of Ophiuchus. The apparent visual magnitude 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 lines of sight and is measured by the angle or semi-angle of inclination between those two lines. Due to foreshortening, nearby objects ...

measurements made during 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, this star is located about from Earth.

Properties

Nu Ophiuchi has about three times the mass of the Sun and is roughly 330 million years old. The spectrum 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 grati ...

of K0 IIIa, indicating it is a giant star that has exhausted the supply of hydrogen at its core and evolved away from the

main sequence In astronomy, the main sequence is a continuous and distinctive band of stars that appears on plots of stellar color versus brightness. These color-magnitude plots are known as Hertzsprung–Russell diagrams after their co-developers, Ejnar Her ...

of stars. Unusually, it displays an anomalously low abundance of cyanogen 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 123 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 4,928 K, giving it the cool, orange hue of a K-type star.

Companions

This is not a

binary star A binary star 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 using a telescope as separate stars, in wh ...

system in the sense of having a gravitationally-bound stellar companion. However, in November 2003, a brown dwarf companion Nu Ophiuchi b was discovered. This sub-stellar companion has at least 21.9 times the mass of Jupiter and takes 536 days (1.47 years) to complete an orbit. 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 have been confirmed in 2012. Two brown dwarfs are locked in 1:6 orbital resonance. This star is following an orbit through the galaxy that carries the star between from the Galactic Center. As a probable member of the Milky Way's

thin disk population 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 outsid ...

, it has a low orbital inclination that carries it no more than about above the galactic plane.

Naming

This star is sometimes called by the name Sinistra, meaning ''left side'' in Latin, although authors like

Jim Kaler James Bailey "Jim" Kaler (December 29, 1938 — November 26, 2022) was an American astronomer and science writer. After elementary and high-school education in Albany, New York, Kaler earned his A.B. at the University of Michigan in 1960. He atten ...

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. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...

, 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 112 Herculis is a binary star system in the northern constellation of Hercules. It is dimly visible to the naked eye with a combined apparent visual magnitude of 5.43. The secondary component is about two magnitudes fainter than the prim ...

, ζ Aquilae, θ¹ Serpentis, η Serpentis, ξ Serpentis and η Ophiuchi. Consequently, ν Ophiuchi itself is known as (, en, the Ninth Star of Left Wall of Heavenly Market Enclosure), and together with ζ Capricorni represents the state Yan (燕) in the '' Twelve States'' constellation.

References

{{DEFAULTSORT:Nu Ophiuchi Ophiuchi, Nu Ophiuchus (constellation) 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