12 Ophiuchi information

12 Ophiuchi
Observation data; Epoch J2000 Equinox J2000
Constellation	Ophiuchus
Right ascension	16h 36m 21.44979s
Declination	–02° 19′ 28.5195″
Apparent magnitude (V)	5.77
Characteristics
Spectral type	K1 V
U−B color index	+0.50
B−V color index	+.82
Variable type	BY Draconis
Astrometry
Radial velocity (Rv)	–15.4 km/s
Proper motion (μ)	RA: +456.04 mas/yr ; Dec.: –309.63 mas/yr
Parallax (π)	102.55 ± 0.40 mas
Distance	31.8 ± 0.1 ly ; (9.75 ± 0.04 pc)
Absolute magnitude (MV)	5.57 ± 0.05
Details
Mass	0.91 M☉
Radius	0.84 ± 0.03 R☉
Luminosity	0.39 L☉
Luminosity (bolometric)	0.45 L☉
Surface gravity (log g)	4.59 ± 0.10 cgs
Temperature	5,300 K
Metallicity	102% Sun
Metallicity [Fe/H]	+0.04 ± 0.07 dex
Rotation	21.3 days
Rotational velocity (v sin i)	2.4 ± 1.0 km/s
Age	1.0–1.9 Gyr
Other designations
	12 Oph, BD-01 3220, FK5 1433, GCTP 3773.00, GJ 631, HD 149661, HIP 81300, HR 6171, LHS 3224, LTT 6632, V2133 Oph, SAO 141269.
Database references
SIMBAD	data
ARICNS	data

12 Ophiuchi is a variable star in the constellation Ophiuchus. No companions have yet been detected in orbit around this star, and it remains uncertain whether or not it possesses a dust ring.^[7]

This star is categorized as a BY Draconis variable, with variable star designation V2133. The variability is attributed to large-scale magnetic activity on the chromosphere (in the form of starspots) combined with a rotational period that moved the active regions into (and out of) the line of sight. This results in low amplitude variability of 12 Ophiuchi's luminosity. The star also appears to display rapid variation in luminosity, possibly due to changes in the starspots.^[8] Measurements of the long-term variability show two overlapping cycles of starspot activity (compared to the Sun's single, 11-year cycle.) The periods of these two cycles are 4.0 and 17.4 years.^[9]

This star is among the top 100 target stars for NASA's planned Terrestrial Planet Finder mission [1]. However, the mission is now postponed indefinitely.

Its abundance of heavy elements (elements heavier than helium) is nearly identical to that of the Sun. The surface gravity is equal to $\log(g)=4.6$ , which is somewhat higher than the Sun's.^[4] The space velocity is 30 km/s relative to the Solar System. The high rotation period and active chromosphere are indicative of a relatively young star.^[10]^[11]

^ ^a ^b ^c ^d ^e Cite error: The named reference aaa474_2_653 was invoked but never defined (see the help page).
^ ^a ^b ^c ^d ^e ^f ^g Cite error: The named reference mnras384_1_173 was invoked but never defined (see the help page).
^ Cite error: The named reference Houk1999 was invoked but never defined (see the help page).
^ ^a ^b ^c Cite error: The named reference flynn_morel was invoked but never defined (see the help page).
^ Cite error: The named reference apj510_2_L135 was invoked but never defined (see the help page).
^ Cite error: The named reference apj687 was invoked but never defined (see the help page).
^ H. J. Habing; P. Bouchet; C. Dominik; T. Encrenaz; A. Heske; M. Jourdain de Muizon; et al. (1996). "First results from a photometric infrared survey for Vega-like disks around nearby main-sequence stars". Astronomy and Astrophysics. 315: L233–L236. Bibcode:1996A&A...315L.233H.
^ J. D. Dorren; E. F. Guinan; E. F. (1982). "Evidence for starspots on single solar-like stars". Astronomical Journal. 87: 1546–1557. Bibcode:1982AJ.....87.1546D. doi:10.1086/113245.
^ "H-K Project: Activity Cycles". Mount Wilson Observatory. Archived from the original on 2007-02-09. Retrieved 2006-12-04.
^ H. J. Rocha-Pinto; B. V. Castilho; W. J. Maciel (2002). "Chromospherically young, kinematically old stars". Astronomy & Astrophysics. 384 (3): 912–924. arXiv:astro-ph/0112452. Bibcode:2002A&A...384..912R. doi:10.1051/0004-6361:20011815. S2CID 16982360.
^ G. F. Porto de Mello; E. F. del Peloso; L. Ghezzi (2006). "Astrobiologically interesting stars within 10 parsecs of the Sun". Astrobiology. 6 (2): 308–331. arXiv:astro-ph/0511180. Bibcode:2006AsBio...6..308P. doi:10.1089/ast.2006.6.308. PMID 16689649. S2CID 119459291.

[aaa474_2_653-1] Cite error: The named reference aaa474_2_653 was invoked but never defined (see the help page).

[mnras384_1_173-2] ^ ^a ^b ^c ^d ^e ^f ^g Cite error: The named reference mnras384_1_173 was invoked but never defined (see the help page).

[Houk1999-3] Cite error: The named reference Houk1999 was invoked but never defined (see the help page).

[flynn_morel-4] Cite error: The named reference flynn_morel was invoked but never defined (see the help page).

[apj510_2_L135-5] Cite error: The named reference apj510_2_L135 was invoked but never defined (see the help page).

[apj687-6] Cite error: The named reference apj687 was invoked but never defined (see the help page).

[7] H. J. Habing; P. Bouchet; C. Dominik; T. Encrenaz; A. Heske; M. Jourdain de Muizon; et al. (1996). "First results from a photometric infrared survey for Vega-like disks around nearby main-sequence stars". Astronomy and Astrophysics. 315: L233–L236. Bibcode:1996A&A...315L.233H.

[8] J. D. Dorren; E. F. Guinan; E. F. (1982). "Evidence for starspots on single solar-like stars". Astronomical Journal. 87: 1546–1557. Bibcode:1982AJ.....87.1546D. doi:10.1086/113245.

[9] "H-K Project: Activity Cycles". Mount Wilson Observatory. Archived from the original on 2007-02-09. Retrieved 2006-12-04.

[10] H. J. Rocha-Pinto; B. V. Castilho; W. J. Maciel (2002). "Chromospherically young, kinematically old stars". Astronomy & Astrophysics. 384 (3): 912–924. arXiv:astro-ph/0112452. Bibcode:2002A&A...384..912R. doi:10.1051/0004-6361:20011815. S2CID 16982360.

[11] G. F. Porto de Mello; E. F. del Peloso; L. Ghezzi (2006). "Astrobiologically interesting stars within 10 parsecs of the Sun". Astrobiology. 6 (2): 308–331. arXiv:astro-ph/0511180. Bibcode:2006AsBio...6..308P. doi:10.1089/ast.2006.6.308. PMID 16689649. S2CID 119459291.

Observation data Epoch J2000 Equinox J2000
Constellation	Ophiuchus
Right ascension	16^h 36^m 21.44979^s^[1]
Declination	–02° 19′ 28.5195″^[1]
Apparent magnitude (V)	5.77^[2]
Characteristics
Spectral type	K1 V^[3]
U−B color index	+0.50
B−V color index	+.82
Variable type	BY Draconis
Astrometry

Radial velocity (R_v)	–15.4 km/s
Proper motion (μ)	RA: +456.04^[1] mas/yr Dec.: –309.63^[1] mas/yr
Parallax (π)	102.55 ± 0.40 mas^[1]
Distance	31.8 ± 0.1 ly (9.75 ± 0.04 pc)
Absolute magnitude (M_V)	5.57 ± 0.05^[2]

Details

Mass	0.91^[2] `M`_☉
Radius	0.84 ± 0.03^[2] `R`_☉
Luminosity	0.39 `L`_☉
Luminosity (bolometric)	0.45 `L`_☉
Surface gravity (log g)	4.59 ± 0.10^[2] cgs
Temperature	5,300^[4] K
Metallicity	102% Sun^[4]
Metallicity [Fe/H]	+0.04 ± 0.07^[2] dex
Rotation	21.3 days^[5]
Rotational velocity (v sin i)	2.4 ± 1.0^[2] km/s
Age	1.0–1.9^[6] Gyr

Other designations
12 Oph, BD-01 3220, FK5 1433, GCTP 3773.00, GJ 631, HD 149661, HIP 81300, HR 6171, LHS 3224, LTT 6632, V2133 Oph, SAO 141269.
Database references
SIMBAD	data
ARICNS	data

12 Ophiuchi information

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