Nu Ophiuchi

ν Ophiuchi
	Location of ν Ophiuchi (circled)
Observation data; Epoch J2000 Equinox J2000
Constellation	Ophiuchus
Right ascension	17h 59m 01.59221s
Declination	−09° 46′ 25.081″
Apparent magnitude (V)	+3.332
Characteristics
Spectral type	K0 IIIa CN –1
U−B color index	+0.873
B−V color index	+0.999
Astrometry
Radial velocity (Rv)	13.19±0.04 km/s
Proper motion (μ)	RA: −7.707 mas/yr ; Dec.: −116.38 mas/yr
Parallax (π)	22.9031 ± 0.1922 mas
Distance	142 ± 1 ly ; (43.7 ± 0.4 pc)
Absolute magnitude (MV)	–0.19
Details
Mass	2.88±0.12 M☉
Radius	13.85±0.17 R☉
Luminosity	108.2±6 L☉
Surface gravity (log g)	2.60±0.03 cgs
Temperature	5,000±63 K
Metallicity [Fe/H]	0.05±0.07 dex
Rotational velocity (v sin i)	2.1 km/s
Age	450±70 Myr
Other designations
	Sinistra, 64 Ophiuchi, BD–09 4632, FK5 673, HD 163917, HIP 88048, HR 6698, SAO 142004, 2MASS J17590160-0946249
Database references
SIMBAD	data

Nu Ophiuchi (ν Oph, ν Ophiuchi) is a star in the equatorial constellation of Ophiuchus. The apparent visual magnitude is +3.3,^[2] making it one of the brighter members of this constellation. Based upon parallax measurements made by the Gaia spacecraft, this star is located about 142 light-years (44 parsecs) from Earth.^[1]

Properties

Nu Ophiuchi has about three times the mass of the Sun and is roughly 450 million years old. ^[4] 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. 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 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,^[6] giving it the cool, orange hue of a K-type star.^[9]

Companions

This is not a binary star system in the sense of having a gravitationally-bound stellar companion.^[10] However, in November 2003, a brown dwarf companion called 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.^[11] 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.^[12] The two brown dwarfs are locked in a 1:6 orbital resonance.^[13]

The Nu Ophiuchi planetary system^[13]
Companion (in order from star)	Mass	Semimajor axis (AU)	Orbital period (days)	Eccentricity	Inclination	Radius
b	22.2-81.7 $M$ _J	1.803	530.73±0.10	0.124±0.003	16-90°	—
c	24.7-92.0 $M$ _J	6.022	3188.95±6.26	0.178±0.006	16-90°	—

This star is following an orbit through the galaxy that carries it 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.^[14]

Naming

This star is sometimes called by the name Sinistra, meaning left side in Latin,^[15] although authors like Jim Kaler recommend not using this name, and instead stick to the Bayer designation only (Nu Ophiuchi).^[16]

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.^[17] 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)^[18]^[19] in the Twelve States constellation.^[20]

References

^ ^a ^b ^c ^d ^e Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
^ ^a ^b ^c ^d Gutierrez-Moreno, Adelina; et al. (1966), "A System of photometric standards", Publications of the Department of Astronomy University of Chile, 1, Publicaciones Universidad de Chile, Department de Astronomy: 1–17, Bibcode:1966PDAUC...1....1G
^ ^a ^b ^c Morgan, W. W.; Keenan, P. C. (1973), "Spectral Classification", Annual Review of Astronomy and Astrophysics, 11 (1): 29, Bibcode:1973ARA&A..11...29M, doi:10.1146/annurev.aa.11.090173.000333
^ ^a ^b ^c Jofré, E.; Petrucci, R.; Saffe, C.; Saker, L.; Artur de la Villarmois, E.; Chavero, C.; Gómez, M.; Mauas, P. J. D. (2015-02-01). "Stellar parameters and chemical abundances of 223 evolved stars with and without planets". Astronomy and Astrophysics. 574: A50. arXiv:1410.6422. Bibcode:2015A&A...574A..50J. doi:10.1051/0004-6361/201424474. ISSN 0004-6361. S2CID 53666931. Nu Ophiuchi's database entry at VizieR.
^ Takeda, Yoichi; Sato, Bun'ei; Murata, Daisuke (August 2008), "Stellar parameters and elemental abundances of late-G giants", Publications of the Astronomical Society of Japan, 60 (4): 781–802, arXiv:0805.2434, Bibcode:2008PASJ...60..781T, doi:10.1093/pasj/60.4.781
^ ^a ^b ^c ^d Baines, Ellyn K.; Armstrong, J. Thomas; Schmitt, Henrique R.; Zavala, R. T.; Benson, James A.; Hutter, Donald J.; Tycner, Christopher; Van Belle, Gerard T. (2018), "Fundamental Parameters of 87 Stars from the Navy Precision Optical Interferometer", The Astronomical Journal, 155 (1): 30, arXiv:1712.08109, Bibcode:2018AJ....155...30B, doi:10.3847/1538-3881/aa9d8b, S2CID 119427037.
^ Massarotti, Alessandro; et al. (January 2008), "Rotational and Radial Velocities for a Sample of 761 HIPPARCOS Giants and the Role of Binarity", The Astronomical Journal, 135 (1): 209–231, Bibcode:2008AJ....135..209M, doi:10.1088/0004-6256/135/1/209, S2CID 121883397
^ "nu. Oph". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2012-02-19.
^ "The Colour of Stars", Australia Telescope, Outreach and Education, Commonwealth Scientific and Industrial Research Organisation, December 21, 2004, archived from the original on December 3, 2013, retrieved 2012-01-16
^ Eggleton, P. P.; Tokovinin, A. A. (September 2008). "A catalogue of multiplicity among bright stellar systems". Monthly Notices of the Royal Astronomical Society. 389 (2): 869–879. arXiv:0806.2878. Bibcode:2008MNRAS.389..869E. doi:10.1111/j.1365-2966.2008.13596.x. S2CID 14878976.
^ Mitchell, D. S.; Frink, S.; Quirrenbach, A.; Fischer, D. A.; Marcy, G. W.; Butler, R. P. (2003), "Four Substellar Companions Found Around K Giant Stars", American Astronomical Society Meeting 203, 203, American Astronomical Society: 1234, Bibcode:2003AAS...203.1703M
^ Sato, Bun'ei; et al. (2012). "Substellar Companions to Seven Evolved Intermediate-Mass Stars". Publications of the Astronomical Society of Japan. 64 (6). 135. arXiv:1207.3141. Bibcode:2012PASJ...64..135S. doi:10.1093/pasj/64.6.135.
^ ^a ^b Quirrenbach, Andreas; Trifonov, Trifon; Lee, Man Hoi; Reffert, Sabine (2019), "Precise radial velocities of giant stars", Astronomy & Astrophysics, 624: A18, arXiv:1904.03557, doi:10.1051/0004-6361/201834423, S2CID 102351148
^ Soubiran, C.; et al. (2008), "Vertical distribution of Galactic disk stars. IV. AMR and AVR from clump giants", Astronomy and Astrophysics, 480 (1): 91–101, arXiv:0712.1370, Bibcode:2008A&A...480...91S, doi:10.1051/0004-6361:20078788, S2CID 16602121
^ "Sinistra".
^ Kaler, Jim. "Nu Ophiuchi". Retrieved 2017-01-03.
^ 陳久金 (2005), 中國星座神話 (in Chinese), 台灣書房出版有限公司, ISBN 978-986-7332-25-7
^ AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 6 月 23 日 (in Chinese)
^ English-Chinese Glossary of Chinese Star Regions, Asterisms and Star Name (in Chinese), Hong Kong Space Museum, archived from the original on September 24, 2008, retrieved November 23, 2010
^ AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 4 日 (in Chinese)