Pi Capricorni

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Pi Capricorni
Observation data
Epoch 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] or B4 V[4][5]
U−B color index −0.311[2]
B−V color index +0.013[2]
Astrometry
Radial velocity (Rv) −13[6] km/s
Proper motion (μ) RA: +11.89[1] mas/yr
Dec.: −11.35[1] mas/yr
Parallax (π) 5.98 ± 0.58[1] mas
Distance 550 ± 50 ly
(170 ± 20 pc)
Details
π Cap Aa
Mass 5.9±0.1[5] M
Luminosity 238[7] L
Temperature 9,623[7] K
Rotational velocity (v sin i) 30[8] km/s
Age 43.4±7.8[5] Myr
Other designations
Okul, π Cap, 10 Cap, ADS 13860, BD−18° 5685, HD 194636, HIP 100881, HR 7814, SAO 163592, WDS J20273-1813AB[9]
Database references
SIMBAD data

Pi Capricorni (π Cap, π Capricorni) is a triple star in the southern constellation of Capricornus. It has the traditional star name Okul or Oculus (meaning eye in Latin).[10] The system is approximately 550 light years from Earth.

In Chinese, 牛宿 (Niú Su), meaning Ox (asterism), refers to an asterism consisting of π Capricorni, β Capricorni, α2 Capricorni, ξ2 Capricorni, ο Capricorni and ρ Capricorni.[11] Consequently, π Capricorni itself is known as 牛宿四 (Niú Su sì, English: the Fourth Star of Ox.)[12]

The primary member, component A, is a spectroscopic binary whose two components are separated by 0.1 arcseconds. The brighter of the two, component Aa, is a blue-white B-type bright giant or main sequence star with an apparent magnitude of +5.08. The third member, component B, is an eighth magnitude star 3.4 arcseconds from the primary.[13]

References[edit]

  1. ^ a b c d e van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, Bibcode:2007A&A...474..653V, arXiv:0708.1752Freely accessible, doi:10.1051/0004-6361:20078357. 
  2. ^ a b c 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. 
  3. ^ Cowley, A. (November 1972), "Spectral classification of the bright B8 stars", Astronomical Journal, 77: 750–755, Bibcode:1972AJ.....77..750C, doi:10.1086/111348. 
  4. ^ Houk, N.; Smith-Moore, M. (1988), Michigan Catalogue of Two-dimensional Spectral Types for the HD Stars, 4, Bibcode:1988MSS...C04....0H. 
  5. ^ 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, Bibcode:2011MNRAS.410..190T, arXiv:1007.4883Freely accessible, doi:10.1111/j.1365-2966.2010.17434.x. 
  6. ^ Wilson, Ralph Elmer (1953), General Catalogue of Stellar Radial Velocities, Washington: Carnegie Institution of Washington, Bibcode:1953GCRV..C......0W. 
  7. ^ a b McDonald, I.; et al. (2012), "Fundamental parameters and infrared excesses of Hipparcos stars", Monthly Notices of the Royal Astronomical Society, 427: 343, Bibcode:2012MNRAS.427..343M, doi:10.1111/j.1365-2966.2012.21873.x. 
  8. ^ 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. 
  9. ^ "pi. Cap -- Spectroscopic binary", SIMBAD Astronomical Database, Centre de Données astronomiques de Strasbourg, retrieved 2017-05-12. 
  10. ^ Oculus, constellationsofwords, retrieved 2017-05-13. 
  11. ^ (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.
  12. ^ (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 5 月 13 日
  13. ^ 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. 

External links[edit]

  • Kaler, James B. (November 7, 2014), "Pi Capricorni", Stars, University of Illinois, retrieved 2017-05-13. </ref>