Astronomy:Pi Capricorni
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| Observation data 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 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: +16.914[6] mas/yr Dec.: −16.983[6] mas/yr |
| Parallax (π) | 4.9614 ± 0.3495[6] mas |
| Distance | 660 ± 50 ly (200 ± 10 pc) |
| Absolute magnitude (MV) | −1.01[7] |
| Details | |
| π Cap Aa | |
| Mass | 5.9±0.1[8] M☉ |
| Luminosity | 238[9] L☉ |
| Temperature | 9,623[9] K |
| Rotational velocity (v sin i) | 30[10] km/s |
| Age | 43.4±7.8[8] Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
Pi Capricorni, Latinized from π Capricorni, is a triple star system in the southern constellation of Capricornus. It has the traditional star name Okul[citation needed] or Oculus (meaning eye in Latin).[12] This system appears blue-white in hue and is visible to the naked eye as a 5th magnitude star.[2] It is located approximately 660 light years distant from the Sun based on parallax,[6] but is drifting closer with a radial velocity of −13 km/s.[5]
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.[8] The star is radiating 238 times the Sun's luminosity from its photosphere at an effective temperature of 9,623 K.[9] The third member, component B, is an eighth magnitude star at an angular separation of 3.4″ from the primary.[15]
References
- ↑ 1.0 1.1 van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics 474 (2): 653–664, doi:10.1051/0004-6361:20078357, Bibcode: 2007A&A...474..653V.
- ↑ 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.
- ↑ Cowley, A. (November 1972), "Spectral classification of the bright B8 stars", Astronomical Journal 77: 750–755, doi:10.1086/111348, Bibcode: 1972AJ.....77..750C.
- ↑ Houk, N.; Smith-Moore, M. (1988), Michigan Catalogue of Two-dimensional Spectral Types for the HD Stars, 4, Bibcode: 1988mcts.book.....H.
- ↑ 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.
- ↑ 6.0 6.1 6.2 6.3 Brown, A. G. A. (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics 616: A1. doi:10.1051/0004-6361/201833051. Bibcode: 2018A&A...616A...1G. Gaia DR2 record for this source at VizieR.
- ↑ Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters 38 (5): 331, doi:10.1134/S1063773712050015, Bibcode: 2012AstL...38..331A.
- ↑ 8.0 8.1 8.2 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.
- ↑ 9.0 9.1 9.2 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.
- ↑ 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.
- ↑ "pi. Cap". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=pi.+Cap.
- ↑ Oculus, constellationsofwords, http://www.constellationsofwords.com/stars/Oculus.html, retrieved 2017-05-13.
- ↑ (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
- ↑ 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.
External links
- Kaler, James B. (November 7, 2014), "Pi Capricorni", Stars (University of Illinois), http://stars.astro.illinois.edu/sow/picap.html, retrieved 2017-05-13.
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