Pi Puppis

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Pi Puppis
Diagram showing star positions and boundaries of the Puppis constellation and its surroundings
Cercle rouge 100%.svg

Location of π Puppis (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Puppis
Right ascension 07h 17m 08.55678s[1]
Declination −37° 05′ 50.8962″[1]
Apparent magnitude (V) 2.733[2]
Spectral type K3 Ib[3]
U−B color index +1.238[2]
B−V color index +1.608[2]
Variable type SRd[4]
Radial velocity (Rv) +15.8[5] km/s
Proper motion (μ) RA: −10.05[1] mas/yr
Dec.: +6.47[1] mas/yr
Parallax (π) 4.04 ± 0.33[1] mas
Distance 810 ± 70 ly
(250 ± 20 pc)
Absolute magnitude (MV) 4.5[6]
Mass 11.7 ± 0.2[7] M
Radius 48[8] R
Luminosity 11,825[9] L
Temperature 3,990–4,055[10] K
Age 20.0 ± 3.9[7] Myr
Other designations
π Pup, CCDM J07171-3706A, CPD−36° 1211, FK5 278, GC 9706, HD 56855, HIP 35264, HR 2773, PPM 283747, SAO 197795, WDS J07171-3706Aa,Ab.[11]
Database references

Pi Puppis (Pi Pup, π Puppis, π Pup), also named Ahadi,[12] is the second-brightest star in the southern constellation of Puppis. It has an apparent visual magnitude of 2.733,[2] so it can be viewed with the naked eye at night. Parallax measurements yield an estimated distance of roughly 810 light-years (250 parsecs) from the Earth.[1] This is a double star with a magnitude 6.86 companion at an angular separation of 0.72 arcsecond and a position angle of 148°.[13]

The spectrum of Pi Puppis matches a stellar classification of K3 Ib.[3] The Ib luminosity class indicates this a lower luminosity supergiant star that has consumed the hydrogen fuel at its core, evolved away from the main sequence, and expanded to about 48 times the Sun's radius.[8] The effective temperature of the star's outer envelope is about 4,000 K,[10] which gives it the orange hue of a K-type star.[14] It is a semiregular variable star[4] that varies in apparent magnitude from a high of 2.70 down to 2.85.[15] Pi Puppis is the brightest star in the open cluster Collinder 135.[16]


In Chinese, 弧矢 (Hú Shǐ), meaning Bow and Arrow,[17] refers to an asterism consisting of π Puppis, δ Canis Majoris, η Canis Majoris, HD 63032, HD 65456, ο Puppis, k Puppis, ε Canis Majoris and κ Canis Majoris. Consequently, π Puppis itself is known as 弧矢九 (Hú Shǐ jiǔ, English: the Ninth Star of Bow and Arrow.)[18]


  1. ^ a b c d e f van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752Freely accessible, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357 
  2. ^ a b c d Gutierrez-Moreno, Adelina; et al. (1966), "A System of photometric standards", Publ. Dept. Astron. Univ. Chile, Publicaciones Universidad de Chile, Department de Astronomy, 1: 1–17, Bibcode:1966PDAUC...1....1G 
  3. ^ a b Houk, Nancy (1979), "Michigan catalogue of two-dimensional spectral types for the HD stars", Michigan Catalogue of Two-dimensional Spectral Types for the HD stars. Volume_3. Declinations -40_ƒ0 to -26_ƒ0, Ann Arbor, Michigan: Dept. of Astronomy, University of Michigan, 3, Bibcode:1982MSS...C03....0H 
  4. ^ a b Kazarovets, E. V.; et al. (January 1999), "The 74th Special Name-list of Variable Stars", Information Bulletin on Variable Stars, 4659: 1, Bibcode:1999IBVS.4659....1K 
  5. ^ Evans, D. S. (June 20–24, 1966). "The Revision of the General Catalogue of Radial Velocities". In Batten, Alan Henry; Heard, John Frederick. Determination of Radial Velocities and their Applications, Proceedings from IAU Symposium no. 30. Determination of Radial Velocities and their Applications. 30. University of Toronto: International Astronomical Union. p. 57. Bibcode:1967IAUS...30...57E. 
  6. ^ Parsons, Sidney B. (2001). "A Large Spectral Class Dependence of the Wilson-Bappu Effect among Luminous Stars". The Publications of the Astronomical Society of the Pacific. 113 (780): 188. Bibcode:2001PASP..113..188P. doi:10.1086/318616. 
  7. ^ a b Tetzlaff, N.; Neuhäuser, R.; Hohle, M. M. (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:1007.4883Freely accessible, Bibcode:2011MNRAS.410..190T, doi:10.1111/j.1365-2966.2010.17434.x 
  8. ^ a b Pasinetti Fracassini, L. E.; Pastori, L.; Covino, S.; Pozzi, A. (February 2001), "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS)", Astronomy and Astrophysics (3rd ed.), 367: 521–524, arXiv:astro-ph/0012289Freely accessible, Bibcode:2001A&A...367..521P, doi:10.1051/0004-6361:20000451. 
  9. ^ McDonald, I.; et al. (2012), "Fundamental Parameters and Infrared Excesses of Hipparcos Stars", Monthly Notices of the Royal Astronomical Society, 427 (1): 343–57, arXiv:1208.2037Freely accessible, Bibcode:2012MNRAS.427..343M, doi:10.1111/j.1365-2966.2012.21873.x. 
  10. ^ a b Pérez Martínez, M. Isabel; Schröder, K.-P.; Cuntz, M. (June 2011), "The basal chromospheric Mg II h+k flux of evolved stars: probing the energy dissipation of giant chromospheres", Monthly Notices of the Royal Astronomical Society, 414 (1): 418–427, arXiv:1102.4832Freely accessible, Bibcode:2011MNRAS.414..418P, doi:10.1111/j.1365-2966.2011.18421.x 
  11. ^ "CCDM J07171-3706A -- Double or multiple star", SIMBAD, Centre de Données astronomiques de Strasbourg 
  12. ^ http://server7.sky-map.org/starview?object_type=1&object_id=317&locale=EN
  13. ^ Fabricius, C.; Makarov, V. V. (April 2000), "Two-colour photometry for 9473 components of close Hipparcos double and multiple stars", Astronomy and Astrophysics, 356: 141–145, Bibcode:2000A&A...356..141F 
  14. ^ "The Colour of Stars", Australia Telescope, Outreach and Education, Commonwealth Scientific and Industrial Research Organisation, December 21, 2004, retrieved 2012-01-16 
  15. ^ Burnham, Robert (1978), Burnham's celestial handbook: an observer's guide to the universe beyond the solar system, Dover books explaining science, 3 (2nd ed.), Courier Dover Publications, p. 1499, ISBN 0-486-23673-0 
  16. ^ Eggen, O. J. (February 1983), "Six clusters in Puppis-Vela", Astronomical Journal, 88: 197–214, Bibcode:1983AJ.....88..197E, doi:10.1086/113306 
  17. ^ 弧矢 (Hú Shǐ) is westernized into Koo She. R.H. Allen had opinion that Koo She refers to the asterism including δ Velorum and ω Velorum. AEEA opinion is, δ Velorum is member of 天社 (Tiān Shè), meaning Celestial Earth God's Temple asterism and ω Velorum is not member of any asterisms. 天社 (Tiān Shè)is westernized into Tseen She and R.H.Allen used the term Tseen She for Chinese name of η Carinae. See Richard Hinckley Allen: Star Names — Their Lore and Meaning: Argo Navis and (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 17 日.
  18. ^ (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 16 日

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