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
Declination −18° 12′ 42.10″
Apparent magnitude (V) +5.096
Characteristics
Spectral type B8 II-III or B3-5 V
U−B color index −0.311
B−V color index +0.013
Astrometry
Radial velocity (Rv)−13 km/s
Proper motion (μ) RA: +16.560 mas/yr
Dec.: −17.375 mas/yr
Parallax (π)5.0291±0.1530 mas
Distance650 ± 20 ly
(199 ± 6 pc)
Absolute magnitude (MV)−1.01
Details
π Cap Aa
Mass5.9±0.1 M☉
Luminosity238 L☉
Temperature9,623 K
Rotational velocity (v sin i)30 km/s
Age43.4±7.8 Myr
Other designations
Oculus, π Cap, 10 Cap, BD−18°5685, HD 194636, HIP 100881, HR 7814, SAO 163592, ADS 13860, WDS J20273-1813AB
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); 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. It is located approximately 650 light-years (200 pc) 660 light years distant from the Sun based on parallax, but is drifting closer with a radial velocity of −13 km/s. The proximity of this star to the ecliptic means it is subject to lunar occultation.

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

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. The star is radiating 238 times the Sun's luminosity from its photosphere at an effective temperature of 9,623 K. The third member, component B, is an eighth magnitude star at an angular separation of 3.4″ from the primary.

References

  1. 1 2 3 4 5 6 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. 1 2 3 4 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. 1 2 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. 1 2 3 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. 1 2 3 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.