- References
- External links
| name=12 Ophiuchi
}}{{Starbox observe
| epoch=J2000
| ra={{RA|16|36|21.44979}}
| dec={{DEC|–02|19|28.5195}}
| appmag_v=5.77[3]
| constell=Ophiuchus
}}{{Starbox character
| class=K1 V[4]
| b-v=+.82
| u-b=+0.50
| variable=BY Draconis
}}{{Starbox astrometry
| radial_v=–15.4
| prop_mo_ra=+456.04
| prop_mo_dec=–309.63
| parallax=102.55
| p_error=0.40
| parallax_footnote=
| absmag_v={{nowrap|5.57 ± 0.05}}[3]
}}{{Starbox detail
| mass=0.91[3]
| radius={{nowrap|0.84 ± 0.03}}[3]
| luminosity=0.39
| luminosity_bolometric=0.45
| gravity={{nowrap|4.59 ± 0.10}}[3]
| temperature=5,300[12]
| metal_fe={{nowrap|+0.04 ± 0.07}}[3]
| metal=102% Sun[12]
| rotation=21.3 days[15]
| rotational_velocity={{nowrap|2.4 ± 1.0}}[3]
| age_gyr=1.0–1.9[17]
}}{{Starbox catalog
| names=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.
}}{{Starbox reference
| Simbad=HD+149661
| ARICNS=01317
}}{{Starbox end}}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.[1]
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.[2] 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.[3]
This star is among the top 100 target stars for NASA's planned Terrestrial Planet Finder mission . 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 
, which is somewhat higher than the Sun's.[12] 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.[4][5]
References
1. ^{{cite journal | display-authors=6 | author=H. J. Habing | author2=P. Bouchet | author3=C. Dominik | author4=T. Encrenaz | author5=A. Heske | author6=M. Jourdain de Muizon | author7=M. F. Kessler | author8=R. Laureijs| author9=K. Leech | author10=L. Metcalfe| author11=A. Salama | author12=R. Siebenmorgen| author13=N. Trams | author14=C. Waelkens| author15=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 | date=1996 | volume=315 | pages=L233–L236 | bibcode=1996A&A...315L.233H }}
2. ^{{cite journal | author=J. D. Dorren | author2=E. F. Guinan | author3= E. F. | title=Evidence for starspots on single solar-like stars | journal=Astronomical Journal | date=1982 | volume=87 | pages=1546–1557 | bibcode=1982AJ.....87.1546D | doi=10.1086/113245 }}
3. ^{{cite web|url=http://www.mtwilson.edu/hk/Cycles/ |title=H-K Project: Activity Cycles |publisher=Mount Wilson Observatory |accessdate=2006-12-04 |deadurl=yes |archiveurl=https://web.archive.org/web/20070209092256/http://www.mtwilson.edu/hk/Cycles/ |archivedate=2007-02-09 |df= }}
4. ^{{cite journal | author=H. J. Rocha-Pinto | author2=B. V. Castilho | author3=W. J. Maciel | title=Chromospherically young, kinematically old stars | journal=Astronomy & Astrophysics | date=2002 | volume=384 | issue=3 | 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 | bibcode=2002A&A...384..912R|arxiv = astro-ph/0112452 }}
5. ^{{cite journal | author=G. F. Porto de Mello | author2=E. F. del Peloso | author3=L. Ghezzi | title=Astrobiologically interesting stars within 10 parsecs of the Sun | journal=Astrobiology | date=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 | pmid=16689649 | bibcode=2006AsBio...6..308P|arxiv = astro-ph/0511180 }}
6. ^1 {{citation | last1=Houk | first1=N. | last2=Swift | first2=C. | title=Michigan catalogue of two-dimensional spectral types for the HD Stars | journal=Michigan Spectral Survey | volume=5 | year=1999 | bibcode=1999MSS...C05....0H | postscript=. }}
7. ^1 2 3 4 5 6 7 {{citation | last1=Fuhrmann | first1=Klaus | title=Nearby stars of the Galactic disc and halo - IV | journal=Monthly Notices of the Royal Astronomical Society | volume=384 | issue=1 | pages=173–224 | doi=10.1111/j.1365-2966.2007.12671.x | bibcode=2008MNRAS.384..173F |date=February 2008}}
8. ^1 2 3 {{citation | first1=C. | last1=Flynn | first2=O. | last2=Morel | title=Metallicities and kinematics of G and K dwarfs | journal=Monthly Notices of the Royal Astronomical Society | date=1997 | volume=286 | issue=3 | pages=617–625 | bibcode=1997MNRAS.286..617F | arxiv=astro-ph/9609017 | doi=10.1093/mnras/286.3.617}}
9. ^1 {{citation | last1=Soon | first1=Willie | last2=Frick | first2=Peter | last3=Baliunas | first3=Sallie | title=Lifetime of Surface Features and Stellar Rotation: A Wavelet Time-Frequency Approach | journal=The Astrophysical Journal | date=1999 | volume=510 | issue=2 | pages=L135–L138 | bibcode=1999ApJ...510L.135S | doi=10.1086/311805 | arxiv=astro-ph/9811114 }}
10. ^1 {{citation | last1=Mamajek | first1=Eric E. | last2=Hillenbrand | first2=Lynne A. | title=Improved Age Estimation for Solar-Type Dwarfs Using Activity-Rotation Diagnostics | journal=The Astrophysical Journal | volume=687 | issue=2 | pages=1264–1293 | doi=10.1086/591785 | bibcode=2008ApJ...687.1264M |arxiv = 0807.1686 |date=November 2008}}
[6][7][8][9][10]2. ^{{cite journal | author=J. D. Dorren | author2=E. F. Guinan | author3= E. F. | title=Evidence for starspots on single solar-like stars | journal=Astronomical Journal | date=1982 | volume=87 | pages=1546–1557 | bibcode=1982AJ.....87.1546D | doi=10.1086/113245 }}
3. ^{{cite web|url=http://www.mtwilson.edu/hk/Cycles/ |title=H-K Project: Activity Cycles |publisher=Mount Wilson Observatory |accessdate=2006-12-04 |deadurl=yes |archiveurl=https://web.archive.org/web/20070209092256/http://www.mtwilson.edu/hk/Cycles/ |archivedate=2007-02-09 |df= }}
4. ^{{cite journal | author=H. J. Rocha-Pinto | author2=B. V. Castilho | author3=W. J. Maciel | title=Chromospherically young, kinematically old stars | journal=Astronomy & Astrophysics | date=2002 | volume=384 | issue=3 | 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 | bibcode=2002A&A...384..912R|arxiv = astro-ph/0112452 }}
5. ^{{cite journal | author=G. F. Porto de Mello | author2=E. F. del Peloso | author3=L. Ghezzi | title=Astrobiologically interesting stars within 10 parsecs of the Sun | journal=Astrobiology | date=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 | pmid=16689649 | bibcode=2006AsBio...6..308P|arxiv = astro-ph/0511180 }}
6. ^1 {{citation | last1=Houk | first1=N. | last2=Swift | first2=C. | title=Michigan catalogue of two-dimensional spectral types for the HD Stars | journal=Michigan Spectral Survey | volume=5 | year=1999 | bibcode=1999MSS...C05....0H | postscript=. }}
7. ^1 2 3 4 5 6 7 {{citation | last1=Fuhrmann | first1=Klaus | title=Nearby stars of the Galactic disc and halo - IV | journal=Monthly Notices of the Royal Astronomical Society | volume=384 | issue=1 | pages=173–224 | doi=10.1111/j.1365-2966.2007.12671.x | bibcode=2008MNRAS.384..173F |date=February 2008}}
8. ^1 2 3 {{citation | first1=C. | last1=Flynn | first2=O. | last2=Morel | title=Metallicities and kinematics of G and K dwarfs | journal=Monthly Notices of the Royal Astronomical Society | date=1997 | volume=286 | issue=3 | pages=617–625 | bibcode=1997MNRAS.286..617F | arxiv=astro-ph/9609017 | doi=10.1093/mnras/286.3.617}}
9. ^1 {{citation | last1=Soon | first1=Willie | last2=Frick | first2=Peter | last3=Baliunas | first3=Sallie | title=Lifetime of Surface Features and Stellar Rotation: A Wavelet Time-Frequency Approach | journal=The Astrophysical Journal | date=1999 | volume=510 | issue=2 | pages=L135–L138 | bibcode=1999ApJ...510L.135S | doi=10.1086/311805 | arxiv=astro-ph/9811114 }}
10. ^1 {{citation | last1=Mamajek | first1=Eric E. | last2=Hillenbrand | first2=Lynne A. | title=Improved Age Estimation for Solar-Type Dwarfs Using Activity-Rotation Diagnostics | journal=The Astrophysical Journal | volume=687 | issue=2 | pages=1264–1293 | doi=10.1086/591785 | bibcode=2008ApJ...687.1264M |arxiv = 0807.1686 |date=November 2008}}
}}
External links
- {{cite web | url = http://www.solstation.com/stars/12ophiu.htm | title = V2133 / 12 Ophiuchi | publisher = SolStation | accessdate = 2006-12-01 }}
11 : Ophiuchus (constellation)|BY Draconis variables|K-type main-sequence stars|Solar-type stars|Flamsteed objects|Henry Draper Catalogue objects|Hipparcos objects|HR objects|Gliese and GJ objects|Objects with variable star designations|Durchmusterung objects
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