Astronomy:Pi Capricorni

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Short description: Star in the constellation Capricornus
Pi Capricorni
Location of π Capricorni (circled)
Observation data
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[1] mas/yr
Dec.: −17.375[1] mas/yr
Parallax (π)5.0291 ± 0.1530[1] mas
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. ↑ 1.0 1.1 1.2 1.3 1.4 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940.  Gaia DR3 record for this source at VizieR.
  2. ↑ 2.0 2.1 2.2 2.3 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, doi:10.1086/111348, Bibcode: 1972AJ.....77..750C. 
  4. ↑ Houk, N.; Smith-Moore, M. (1988), Michigan Catalogue of Two-dimensional Spectral Types for the HD Stars, 4, Bibcode: 1988mcts.book.....H. 
  5. ↑ 5.0 5.1 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. doi:10.1134/S1063773712050015. Bibcode: 2012AstL...38..331A.  XHIP record for this object at VizieR.
  7. ↑ 7.0 7.1 7.2 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, doi:10.1111/j.1365-2966.2010.17434.x, Bibcode: 2011MNRAS.410..190T. 
  8. ↑ 8.0 8.1 8.2 McDonald, I. et al. (2012), "Fundamental parameters and infrared excesses of Hipparcos stars", Monthly Notices of the Royal Astronomical Society 427 (1): 343–357, doi:10.1111/j.1365-2966.2012.21873.x, Bibcode: 2012MNRAS.427..343M. 
  9. ↑ Abt, Helmut A. et al. (July 2002), "Rotational Velocities of B Stars", The Astrophysical Journal 573 (1): 359–365, doi:10.1086/340590, Bibcode: 2002ApJ...573..359A. 
  10. ↑ "pi. Cap". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=pi.+Cap. 
  11. ↑ Oculus, constellationsofwords, http://www.constellationsofwords.com/stars/Oculus.html, retrieved 2017-05-13. 
  12. ↑ Evans, D. S.; Edwards, D. A. (August 1981), "Photoelectric observations of lunar occultations. XII", Astronomical Journal 86: 1277–1287, doi:10.1086/113008, Bibcode: 1981AJ.....86.1277E. 
  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
  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, doi:10.1086/323920, Bibcode: 2001AJ....122.3466M. 



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