Nu Ophiuchi

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Nu Ophiuchi
Diagram showing star positions and boundaries of the Ophiuchus constellation and its surroundings
Cercle rouge 100%.svg

Location of ν Ophiuchi (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Ophiuchus
Right ascension 17h 59m 01.59191s[1]
Declination −09° 46′ 25.0798″[1]
Apparent magnitude (V) +3.332[2]
Characteristics
Spectral type K0 IIIa CN –1[3]
U−B color index +0.873[2]
B−V color index +0.999[2]
Astrometry
Radial velocity (Rv) 12.95 ± 0.41[4] km/s
Proper motion (μ) RA: –9.48[1] mas/yr
Dec.: –116.69[1] mas/yr
Parallax (π) 21.64 ± 0.26[1] mas
Distance 151 ± 2 ly
(46.2 ± 0.6 pc)
Absolute magnitude (MV) –0.19[5]
Details
Mass 3.04[6] M☉
Radius 14[4] R☉
Luminosity 123[6] L☉
Surface gravity (log g) 2.7[4] cgs
Temperature 4,928[6] K
Metallicity [Fe/H] 0.02[4] dex
Rotational velocity (v sin i) 2.1[4] km/s
Age 330[6] Myr
Other designations
Sinistra, 64 Ophiuchi, BD–09 4632, FK5 673, HD 163917, HIP 88048, HR 6698, SAO 142004.[7]
Database references
SIMBAD data

Nu Ophiuchi (ν Oph, ν Ophiuchi) is a star in the equatorial constellation of Ophiuchus. This star is sometimes called by the name Sinistra, meaning left side in Latin.[8] The apparent visual magnitude is +3.3,[2] making it one of the brighter members of this constellation. Based upon parallax measurements made during the Hipparcos mission, this star is located about 151 light-years (46 parsecs) from Earth.[1]

In China, the star is part of 天市左垣 (Tiān Shì Zuǒ Yuán), 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.[9] Consequently, ν Ophiuchi itself is known as 天市左垣九 (Tiān Shì Zuǒ Yuán jiǔ, English: the Ninth Star of Left Wall of Heavenly Market Enclosure), and together with ζ Capricorni represents the state Yan (燕)[10][11] in the Twelve States constellation.[12]

Nu Ophiuchi has about three times the mass of the Sun and is roughly 330 million years old.[6] The spectrum of the star matches a stellar classification of K0 IIIa,[3] 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 like the Sun. Unusually, it displays an anomalously low abundance of cyanogen for a star of its type.[3] The star's outer envelope has expanded to around 14[4] times the Sun's radius and now radiates 123[6] times as much luminosity of the Sun. This energy is being emitted from its outer envelope at an effective temperature of 4,928 K,[6] giving it the cool, orange hue of a K-type star.[13]

This is not a binary star system in the sense of having a gravitationally-bound stellar companion.[14] However, in early 2004, 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.[15] 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.[6]

The Nu Ophiuchi planetary system[15]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b ≥21.9 MJ ≥1.875 536 0.13 — —
c ≥24.5 MJ 5.88 3169 0.18 — —

This star is following an orbit through the galaxy that carries the star between 23.4–29.2 kly (7.2–9.0 kpc) 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 100 ly (31 pc) above the galactic plane.[16]

See also

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 Lua error in package.lua at line 80: module 'strict' not found.
  2. ↑ 2.0 2.1 2.2 2.3 Lua error in package.lua at line 80: module 'strict' not found.
  3. ↑ 3.0 3.1 3.2 Lua error in package.lua at line 80: module 'strict' not found.
  4. ↑ 4.0 4.1 4.2 4.3 4.4 4.5 Lua error in package.lua at line 80: module 'strict' not found.
  5. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  6. ↑ 6.0 6.1 6.2 6.3 6.4 6.5 6.6 6.7 Lua error in package.lua at line 80: module 'strict' not found.
  7. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  8. ↑ http://www.constellationsofwords.com/stars/Sinistra.html
  9. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  10. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  11. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  12. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  13. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  14. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  15. ↑ 15.0 15.1 Lua error in package.lua at line 80: module 'strict' not found.
  16. ↑ Lua error in package.lua at line 80: module 'strict' not found.
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