Pi Capricorni

Pi Capricorni
Location of π Capricorni (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Capricornus
Right ascension 20h 27m 19.202s[1]
Declination −18° 12′ 42.10″[1]
Apparent magnitude (V) +5.096[2]
Characteristics
Spectral type B8 II-III[3] or B3-5 V[4]
U−B color index −0.311[2]
B−V color index +0.013[2]
Astrometry
Radial velocity (Rv)−13[5] km/s
Proper motion (μ) RA: +16.560 mas/yr[1]
Dec.: −17.375 mas/yr[1]
Parallax (π)5.0291±0.1530 mas[1]
Distance650 ± 20 ly
(199 ± 6 pc)
Absolute magnitude (MV)−1.01[6]
Details
π Cap Aa
Mass5.9±0.1[7] M☉
Luminosity238[8] L☉
Temperature9,623[8] K
Rotational velocity (v sin i)30[9] km/s
Age43.4±7.8[7] Myr
Other designations
Oculus, π Cap, 10 Cap, BD−18°5685, HD 194636, HIP 100881, HR 7814, SAO 163592, ADS 13860, WDS J20273-1813AB[10]
Database references
SIMBADdata

Pi Capricorni is a triple star system in the southern constellation of Capricornus. It has the traditional star name Oculus (meaning eye in Latin);[11] Pi Capricorni is its Bayer designation, which is Latinized from π Capricorni and abbreviated Pi Cap or π Cap. This system appears blue-white in hue and is visible to the naked eye as a 5th magnitude star.[2] It is located approximately 650 light-years (200 pc) 660 light years distant from the Sun based on parallax,[1] but is drifting closer with a radial velocity of −13 km/s.[5] The proximity of this star to the ecliptic means it is subject to lunar occultation.[12]

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.[13] Consequently, the Chinese name for π Capricorni itself is 牛宿四 (Niú Su sì, English: the Fourth Star of Ox.)[14]

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. It is around 43 million years old with six times the mass of the Sun.[7] The star is radiating 238 times the Sun's luminosity from its photosphere at an effective temperature of 9,623 K.[8] The third member, component B, is an eighth magnitude star at an angular separation of 3.4″ from the primary.[15]

References

  1. ^ a b c d e Vallenari, A.; et al. (Gaia collaboration) (2023), "Gaia Data Release 3. Summary of the content and survey properties", Astronomy and Astrophysics, 674: A1, arXiv:2208.00211, Bibcode:2023A&A...674A...1G, doi:10.1051/0004-6361/202243940, S2CID 244398875. Gaia DR3 record for this source at VizieR.
  2. ^ 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.
  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, vol. 4, Bibcode:1988mcts.book.....H.
  5. ^ 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.
  6. ^ 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. XHIP record for this object at VizieR.
  7. ^ 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.
  8. ^ a b c McDonald, I.; et al. (2012), "Fundamental parameters and infrared excesses of Hipparcos 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.
  9. ^ 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.
  10. ^ "pi. Cap", SIMBAD, Centre de données astronomiques de Strasbourg, retrieved 2017-05-12.
  11. ^ Oculus, constellationsofwords, retrieved 2017-05-13.
  12. ^ Evans, D. S.; Edwards, D. A. (August 1981), "Photoelectric observations of lunar occultations. XII", Astronomical Journal, 86: 1277–1287, Bibcode:1981AJ.....86.1277E, doi:10.1086/113008.
  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.
  14. ^ (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 the Wayback Machine
  15. ^ 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, retrieved 2017-05-13.
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