12 Ophiuchi

Starbox begin
name=12 Ophiuchi Starbox observe
epoch=J2000
ra=RA|16|36|21.4493
dec=DEC| -02|19|28.501
appmag_v=5.76
constell=Ophiuchus Starbox character
class=K2 V
b-v=0.82
u-b=0.50
variable=BY Draconis Starbox astrometry
radial_v=-15.4
prop_mo_ra=455.23
prop_mo_dec=-307.64
parallax=102.27
p_error=0.85
absmag_v= Starbox detail
mass=?
radius=?
luminosity=?
temperature=5,300cite journal | author=C. Flynn, O. Morel | title=Metallicities and kinematics of G and K dwarfs | journal=Monthly Notices of the Royal Astronomical Society | year=1997 | volume=286 | issue=3 | pages=617–625 | url=http://adsabs.harvard.edu/abs/1996astro.ph..9017F ]
metal=102 % Sun
rotation=21.3 days [cite journal | authpr=W. Soon, P. Frick, S. Baliunas | title=Lifetime of Surface Features and Stellar Rotation: A Wavelet Time-Frequency Approach | journal=The Astrophysical Journal | year=1999 | volume=510 | issue=2 | pages=L135–L138 | url=http://adsabs.harvard.edu/abs/1999ApJ...510L.135S | doi=10.1086/311805 | author=Soon, Willie ]
age=? Starbox catalog
names=12 Oph, V2133 Oph, GJ 631, HR 6171, BD -01 3220, HD 149661, LHS 3224, LTT 6632, GCTP 3773.00, SAO 141269, FK5 1433, HIP 81300. Starbox reference
Simbad=HD+149661
ARICNS=01317

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. [cite journal | author=H. J. Habing, P. Bouchet, C. Dominik, T, Encrenaz, A. Heske, M. Jourdain de Muizon, M. F. Kessler, R. Laureijs, K. Leech, L. Metcalfe, A. Salama, R. Siebenmorgen, N. Trams, C. Waelkens, L. B. F. M. Waters | title=First results from a photometric infrared survey for Vega-like disks around nearby main-sequence stars. | journal=Astronomy and Astrophysics | year=1996 | volume=315 | pages=L233–L236 | url=http://cdsads.u-strasbg.fr/cgi-bin/nph-bib_query?1996A&A...315L.233H ]

This star is categorized as a BY Draconis variable, with variable star designation V2133. The variability of this star 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. [cite journal | author=J. D. Dorren, E. F. Guinan, E. F. | title=Evidence for starspots on single solar-like stars | journal=Astronomical Journal | year=1982 | volume=87 | pages=1546–1557 | url=http://adsabs.harvard.edu/abs/1982AJ.....87.1546D | doi=10.1086/113245 ] Measurements of the long-term variability of this star 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. [cite web | url = http://www.mtwilson.edu/hk/Cycles/ | title = H-K Project: Activity Cycles | publisher = Mount Wilson Observatory | accessdate = 2006-12-04 ]

The abundance of heavy elements (elements heavier than Helium) in this star is nearly identical to the Sun. The surface gravity is equal to $log(g)\; =\; 4.6$, which is somewhat higher than the Sun's. The space velocity of this star is 30 km/s relative to the solar system. The high rotation period and active chromosphere are indicative of a relatively young star. [cite journal | author=H. J. Rocha-Pinto, B. V. Castilho, W. J. Maciel | title=Chromospherically young, kinematically old stars | journal=Astronomy & Astrophysics | year=2002 | volume=384 | pages=912–924 | url=http://www.aanda.org/index.php?option=com_base_ora&url=articles/aa/full/2002/12/aa1635/aa1635.right.html&access=standard&Itemid=81 | doi=10.1051/0004-6361:20011815 ] [cite journal | author=G. F. Porto de Mello, E. F. del Peloso, L. Ghezzi | title=Astrobiologically interesting stars within 10 parsecs of the Sun | journal=Astrobiology | year=2006 | volume=6 | issue=2 | pages=308–331 | url=http://www.liebertonline.com/doi/abs/10.1089/ast.2006.6.308 | doi=10.1089/ast.2006.6.308 ]

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