Nu Ophiuchi
Nu Ophiuchi is a star in the equatorial constellation of Ophiuchus. The apparent visual magnitude is +3.3, making it one of the brighter members of this constellation. Based upon parallax measurements made by the Hipparcos satellite, this star is located at a distance of about.
Nomenclature
Nu Ophiuchi is the star's Bayer designation. This star is sometimes called by the name Sinistra, meaning left side in Latin, usually in an astrological context. Astronomer Jim Kaler recommended not using this name, and instead sticks to the Bayer designation only.In Chinese astronomy, the star is part of 天市左垣, 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, θ1 Serpentis, η Serpentis, ξ Serpentis and η Ophiuchi. Consequently, ν Ophiuchi itself is known as 天市左垣九, and represents the state Yan, together with ζ Capricorni in the Twelve States constellation.
Properties
Nu Ophiuchi has about three times the mass of the Sun and is roughly 450 million years old. The spectrum of the star matches a stellar classification 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 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 108 times that of the Sun. This energy is emitted from its outer envelope at an effective temperature of 5,000 K, giving it the cool, orange hue of a K-type star.This star is following an orbit through the galaxy that carries it between from the Galactic Center. As a probable member of the Milky Way's thin disk population, it has a low orbital inclination that carries it no more than about above the galactic plane.