Star in the constellation Capricornus
Pi Capricorni Location of π Capricorni (circled)
Observation dataEpoch J2000.0 Equinox J2000.0 (ICRS ) Constellation Capricornus Right ascension 20h 27m 19.21088s [ 1] Declination −18° 12′ 42.1980″[ 1] Apparent magnitude (V)+5.096[ 2] Characteristics Spectral type B8 II-III[ 3] [ 4] U−Bcolor index −0.311[ 2] B−Vcolor index +0.013[ 2] Astrometry Radial velocity (Rv )−13[ 5] km/s Proper motion (μ)RA: +16.914[ 6] mas /yr Dec.: −16.983[ 6] mas /yr Parallax (π)4.9614± 0.3495 mas [ 6] Distance 660 ± 50 ly pc ) Absolute magnitude (MV )−1.01[ 7] Details π Cap Aa Mass ± 0.1[ 8] M ☉ Luminosity 238[ 9] L ☉ Temperature 9,623[ 9] K Rotational velocity (v sin i )30[ 10] Age ± 7.8[ 8] Myr Other designations Okul,π Cap ,10 Cap ,ADS 13860,BD −18° 5685,HD 194636,HIP 100881,HR 7814,SAO 163592,WDS J20273-1813AB[ 11] Database references SIMBAD data
Pi Capricorni ,Latinized from π Capricorni, is atriple star system in the southernconstellation ofCapricornus . It has the traditional star nameOkul [citation needed orOculus (meaningeye inLatin ).[ 12] [ 2] light years distant from the Sun based onparallax ,[ 6] radial velocity of −13 km/s.[ 5]
InChinese ,牛宿 Niú Su Ox (asterism)β Capricorni ,α2 Capricorni ,ξ2 Capricorni ,ο Capricorni andρ Capricorni .[ 13] Chinese name for π Capricorni itself is牛宿四 Niú Su sì the Fourth Star of Ox .)[ 14]
The primary member, component A, is aspectroscopic binary whose two components are separated by 0.1arcseconds . The brighter of the two, component Aa, is a blue-whiteB-type bright giant ormain sequence star with anapparent magnitude of +5.08. It is around 43 million years old with six times themass of the Sun .[ 8] Sun's luminosity from itsphotosphere at aneffective temperature of 9,623 K.[ 9] angular separation of″ [ 15]
^a b van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction",Astronomy and Astrophysics ,474 (2):653– 664,arXiv :0708.1752 Bibcode :2007A&A...474..653V ,doi :10.1051/0004-6361:20078357 ,S2CID 18759600 . ^a b c d Rakos, K. D.; et al. (February 1982), "Photometric and astrometric observations of close visual binaries",Astronomy and Astrophysics Supplement Series ,47 :221– 235,Bibcode :1982A&AS...47..221R . ^ Cowley, A. (November 1972), "Spectral classification of the bright B8 stars",Astronomical Journal ,77 :750– 755,Bibcode :1972AJ.....77..750C ,doi :10.1086/111348 . ^ Houk, N.; Smith-Moore, M. (1988),Michigan Catalogue of Two-dimensional Spectral Types for the HD Stars , vol. 4,Bibcode :1988mcts.book.....H . ^a b Wilson, Ralph Elmer (1953), "General Catalogue of Stellar Radial Velocities",Carnegie Institute Washington D.C. Publication , Washington: Carnegie Institution of Washington,Bibcode :1953GCRV..C......0W . ^a b c d Brown, A. G. A. ; et al. (Gaia collaboration) (August 2018)."Gaia Data Release 2: Summary of the contents and survey properties" .Astronomy & Astrophysics 616 . A1.arXiv :1804.09365 Bibcode :2018A&A...616A...1G doi :10.1051/0004-6361/201833051 Gaia DR2 record for this source atVizieR .^ Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation",Astronomy Letters ,38 (5): 331,arXiv :1108.4971 Bibcode :2012AstL...38..331A ,doi :10.1134/S1063773712050015 ,S2CID 119257644 . ^a b c Tetzlaff, N.; et al. (January 2011), "A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun",Monthly Notices of the Royal Astronomical Society 410 (1):190– 200,arXiv :1007.4883 Bibcode :2011MNRAS.410..190T ,doi :10.1111/j.1365-2966.2010.17434.x S2CID 118629873 . ^a b c McDonald, I.; et al. (2012), "Fundamental parameters and infrared excesses ofHipparcos stars",Monthly Notices of the Royal Astronomical Society ,427 (1):343– 357,arXiv :1208.2037 Bibcode :2012MNRAS.427..343M ,doi :10.1111/j.1365-2966.2012.21873.x S2CID 118665352 . ^ Abt, Helmut A.; et al. (July 2002), "Rotational Velocities of B Stars",The Astrophysical Journal ,573 (1):359– 365,Bibcode :2002ApJ...573..359A ,doi :10.1086/340590 ^ "pi. Cap" .SIMBAD Centre de données astronomiques de Strasbourg . Retrieved2017-05-12 .{{cite web }}: CS1 maint: postscript (link )^ Oculus , retrieved2017-05-13 .^ (in Chinese) 中國星座神話 , written by 陳久金. Published by 台灣書房出版有限公司, 2005,ISBN 978-986-7332-25-7 .^ (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 5 月 13 日 Archived 2011-05-22 at theWayback Machine ^ Mason, Brian D.; et al. (2001), "The 2001 US Naval Observatory Double Star CD-ROM. I. The Washington Double Star Catalog",The Astronomical Journal ,122 (6): 3466,Bibcode :2001AJ....122.3466M ,doi :10.1086/323920 Kaler, James B. (November 7, 2014),"Pi Capricorni" ,Stars , University of Illinois, retrieved2017-05-13 .
