Nu Ophiuchi is a Class K0

Stellar classification

In astronomy, stellar classification is a classification of stars based on their spectral characteristics. The spectral class of a star is a designated class of a star describing the ionization of its chromosphere, what atomic excitations are most prominent in the light, giving an objective measure...

, third-magnitude star

Star

A star is a massive, luminous sphere of plasma held together by gravity. At the end of its lifetime, a star can also contain a proportion of degenerate matter. The nearest star to Earth is the Sun, which is the source of most of the energy on Earth...

 in the constellation

Constellation

In modern astronomy, a constellation is an internationally defined area of the celestial sphere. These areas are grouped around asterisms, patterns formed by prominent stars within apparent proximity to one another on Earth's night sky....

 Ophiuchus. Its closest stellar neighbour is the bright binary system Tau Ophiuchi, roughly 16.9 light years away from the star. Sometimes, this star is called by the name Sinistra, meaning left side in Latin

Latin

Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...

.

In Chinese

Chinese language

The Chinese language is a language or language family consisting of varieties which are mutually intelligible to varying degrees. Originally the indigenous languages spoken by the Han Chinese in China, it forms one of the branches of Sino-Tibetan family of languages...

, , meaning Left Wall of Heavenly Market Enclosure

Heavenly Market enclosure

Tian Shi Yuan, the Heavenly Market Enclosure , is one of the San Yuan or Three enclosures. Stars and constellations of this group are visible during late summer and early autumn in the Northern Hemisphere . The summer triangle lies directly to the northwest.-Asterisms:The asterisms are :...

, refers to an asterism which is represent eleven old states in China which is marking the left borderline of the enclosure, consisting of ν Ophiuchi, δ Herculis

Delta Herculis

Delta Herculis is a fourth-magnitude star in the constellation Hercules. It has the traditional name Sarin....

, λ Herculis

Lambda Herculis

Lambda Herculis is a star inthe constellation Hercules.It has the traditional name Maasym .In Chinese, , meaning Left Wall of Heavenly Market Enclosure, refers to an asterism which is represent eleven old states in China which is marking the left borderline of the enclosure, consisting of λ...

, μ Herculis

Mu Herculis

Mu Herculis is a nearby star system about 27.1 light years from Earth in the constellation Hercules. Its main star, Mu Herculis A is fairly similar to the Sun although more highly evolved with a...

, ο Herculis

Omicron Herculis

Omicron Herculis is a multiple star system in the constellation Hercules. It has the traditional name Atia and the Flamsteed designation 103 Herculis.- Properties :...

, 112 Herculis, ζ Aquilae

Zeta Aquilae

Zeta Aquilae is a triple star system in the constellation Aquila. It has the traditional names Deneb el Okab, from an Arabic term ذنب العقاب ðanab al-cuqāb meaning "the tail of the falcon", and the Mandarin names Woo and Yuë, derived from and represent the state Wu , an old state was located at...

, θ¹ Serpentis, η Serpentis

Eta Serpentis

Eta Serpentis is a binary star in the constellation Serpens. The primary, Eta Serpentis A, is an orange K-type giant with an apparent magnitude of +3.23. It has a distant 12th magnitude companion, Eta Serpentis B, 3 arcminutes away...

, ξ Serpentis

Xi Serpentis

Xi Serpentis is a triple star system in the constellation Serpens. The primary star, Xi Serpentis A, is a yellow-white F-type giant with an apparent magnitude of +3.54. It is a spectroscopic binary with an orbital period of 2.29 days. A 13th magnitude companion, Xi Serpentis B, is located 25...

 and η Ophiuchi

Eta Ophiuchi

Eta Ophiuchi, also known as η Oph or η Ophiuchi, is a star in the constellation Ophiuchus. It also has the traditional name Sabik....

. Consequently, ν Ophiuchi itself is known as , represent the state Yan

Yan (state)

Yān was a state during the Western Zhou, Spring and Autumn and Warring States Periods of Chinese history. Its capital was Ji...

(燕), together with ζ Capricorni

Zeta Capricorni

Zeta Capricorni, , is a fourth-magnitude star in the constellation Capricornus. ζ Capricorni is a binary star, with the primary component ζ Capricorni A being a yellow G-type supergiant with an apparent magnitude of +3.77...

 in Twelve States

Girl (Chinese constellation)

The Girl mansion is one of the Twenty-eight mansions of the Chinese constellations. It is one of the northern mansions of the Black Tortoise.- Asterisms :...

asterism.

Nu Ophiuchi is a binary star with components of magnitudes 3.3 and 6.8, separated by 2.7 arcseconds. This stellar system is located about 153 ly from Earth

Earth

Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...

.

The star has a brown dwarf

Brown dwarf

Brown dwarfs are sub-stellar objects which are too low in mass to sustain hydrogen-1 fusion reactions in their cores, which is characteristic of stars on the main sequence. Brown dwarfs have fully convective surfaces and interiors, with no chemical differentiation by depth...

 companion Nu Ophiuchi b discovered in early 2004. The companion has mass

Mass

Mass can be defined as a quantitive measure of the resistance an object has to change in its velocity.In physics, mass commonly refers to any of the following three properties of matter, which have been shown experimentally to be equivalent:...

 of 21.9 M_J

Jupiter mass

Jupiter mass , is the unit of mass equal to the total mass of the planet Jupiter . Jupiter mass is used to describe masses of the gas giants, such as the outer planets and extrasolar planets. It is also used in describing brown dwarfs....

 and takes 536 day

Day

A day is a unit of time, commonly defined as an interval equal to 24 hours. It also can mean that portion of the full day during which a location is illuminated by the light of the sun...

s to complete an orbit

Orbit

In physics, an orbit is the gravitationally curved path of an object around a point in space, for example the orbit of a planet around the center of a star system, such as the Solar System...

.

The second brown dwarf companion discovered in 2010.

See also

• Nu Ophiuchi in fiction
• Tau Geminorum
  Tau Geminorum
  Tau Geminorum is a star in the Gemini constellation. It is an orange giant of the spectral type K2III, meaning it is probably fusing carbon and oxygen in its core to form iron and nickel. It has the apparent magnitude of 4.40, visible to the naked eye with moderate difficulty. The absolute...