Epsilon Delphini

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Epsilon Delphini
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Delphinus
Right ascension 20h 33m 12.77192s[1]
Declination +11° 18′ 11.7412″[1]
Apparent magnitude (V) 4.03[2] (3.95−4.05)[3]
Spectral type B6 III[4]
U−B color index −0.46[2]
B−V color index −0.13[2]
Variable type suspected[3]
Proper motion (μ) RA: +11.96[1] mas/yr
Dec.: −28.97[1] mas/yr
Parallax (π) 9.87 ± 0.21[1] mas
Distance 330 ± 7 ly
(101 ± 2 pc)
Absolute magnitude (MV) −0.06[5]
Radius 4.6[6] R
Luminosity 676[7] L
Surface gravity (log g) 3.65[8] cgs
Temperature 13,614±15[6] K
Rotational velocity (v sin i) 52±4[9] km/s
Other designations
ε Del, 2 Del, BD+10° 4321, FK5 768, HD 195810, HIP 101421, HR 7852, SAO 106230[10]
Database references

Epsilon Delphini (ε Del, ε Delphini) is a solitary,[11] blue-white hued star in the northern constellation of Delphinus. It is visible to the naked eye with an apparent visual magnitude of 4.03.[2] Based upon an annual parallax shift of 9.87 mas as seen from the Earth,[1] the system is located about 330 light years from the Sun. At that distance, the visual magnitude is diminished by an extinction factor of 0.11 due to interstellar dust.[5]

This is a B-type giant star with a stellar classification of B6 III.[4] It has 4.6[6] times the Sun's radius and is radiating 676[7] times the solar luminosity from its photosphere at an effective temperature of 13,614 K.[6] The star may be slightly variable, occasionally brightening to magnitude 3.95.[3]

Proper names[edit]

The term ðanab ad-dulfīn or Dzaneb al Delphin appeared in the catalogue of stars in the Calendarium of Al Achsasi Al Mouakket, which was translated into Latin as Cauda Delphini, meaning the dolphin's tail.[12]

In Chinese, 敗瓜 (Bài Guā), meaning Rotten Gourd, refers to an asterism consisting of ε Delphini, η Delphini, θ Delphini, ι Delphini and κ Delphini.[13] Consequently, ε Delphini itself is known as 敗瓜一 (Bài Guā yī, English: the First Star of Rotten Gourd.).[14] From this Chinese name, the name Pae Chaou was formed.[15]


  1. ^ a b c d e f van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, Bibcode:2007A&A...474..653V, arXiv:0708.1752Freely accessible, doi:10.1051/0004-6361:20078357. 
  2. ^ a b c d Crawford, D. L.; et al. (1971), "Four-color, H-beta, and UBV photometry for bright B-type stars in the northern hemisphere", The Astronomical Journal, 76: 1058, Bibcode:1971AJ.....76.1058C, doi:10.1086/111220. 
  3. ^ a b c Samus, N. N.; et al. (January 2017), "General Catalogue of Variable Stars", Astronomy Reports, GCVS 5.1, 61 (1): 80–88, Bibcode:2017ARep...61...80S, doi:10.1134/S1063772917010085. 
  4. ^ a b Lesh, Janet Rountree (December 1968), "The Kinematics of the Gould Belt: an Expanding Group?", Astrophysical Journal Supplement, 17: 371, Bibcode:1968ApJS...17..371L, doi:10.1086/190179. 
  5. ^ a b Gontcharov, G. A. (November 2012), "Spatial distribution and kinematics of OB stars", Astronomy Letters, 38 (11): 694−706, Bibcode:2012AstL...38..694G, arXiv:1606.09028Freely accessible, doi:10.1134/S1063773712110035. 
  6. ^ a b c d Underhill, A. B.; et al. (November 1979), "Effective temperatures, angular diameters, distances and linear radii for 160 O and B stars", Monthly Notices of the Royal Astronomical Society, 189: 601–605, Bibcode:1979MNRAS.189..601U, doi:10.1093/mnras/189.3.601. 
  7. ^ a b McDonald, I.; et al. (2012), "Fundamental Parameters and Infrared Excesses of Hipparcos Stars", Monthly Notices of the Royal Astronomical Society, 427 (1): 343–57, Bibcode:2012MNRAS.427..343M, arXiv:1208.2037Freely accessible, doi:10.1111/j.1365-2966.2012.21873.x. 
  8. ^ Kocer, D.; et al. (August 2003), "Elemental abundance analyses with DAO spectrograms. XXVII. The superficially normal stars theta And (A2 IV), epsilon Del (B6 III), epsilon Aqr (A1.5 V), and iota And (B9 V)", Astronomy and Astrophysics, 406: 975−980, Bibcode:2003A&A...406..975K, doi:10.1051/0004-6361:20030620. 
  9. ^ Bailey, J. D.; Landstreet, J. D. (2013), "Abundances determined using Si ii and Si iii in B-type stars: Evidence for stratification", Astronomy & Astrophysics, 551: A30, Bibcode:2013A&A...551A..30B, arXiv:1301.3050Freely accessible, doi:10.1051/0004-6361/201220671. 
  10. ^ "eps Del -- Variable Star", SIMBAD Astronomical Database, Centre de Données astronomiques de Strasbourg, retrieved 2017-06-28. 
  11. ^ Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869–879, Bibcode:2008MNRAS.389..869E, arXiv:0806.2878Freely accessible, doi:10.1111/j.1365-2966.2008.13596.x. 
  12. ^ Knobel, E. B. (June 1895), "Al Achsasi Al Mouakket, on a catalogue of stars in the Calendarium of Mohammad Al Achsasi Al Mouakket", Monthly Notices of the Royal Astronomical Society, 55: 429–438, Bibcode:1895MNRAS..55..429K, doi:10.1093/mnras/55.8.429. 
  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) 香港太空館 - 研究資源 - 亮星中英對照表 Archived September 29, 2009, at the Wayback Machine., Hong Kong Space Museum. Accessed on line November 23, 2010.
  15. ^ Allen, R. H. (1963), Star Names, Their Lore and Meaning (Dover ed.), p. 201, retrieved 2017-06-29.