Delta Sagittarii

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Delta Sagittarii
Diagram showing star positions and boundaries of the Sagittarius constellation and its surroundings
Cercle rouge 100%.svg

Location of δ Sagittarii (circled)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Sagittarius
Right ascension 18h 20m 59.64354s[1]
Declination −29° 49′ 41.1659″[1]
Apparent magnitude (V) +2.70[2]
Spectral type K3 III[3]
U−B color index +1.55[2]
B−V color index +1.38[2]
Radial velocity (Rv) –19.9[4] km/s
Proper motion (μ) RA: +32.54[1] mas/yr
Dec.: −25.57[1] mas/yr
Parallax (π) 9.38 ± 0.18[1] mas
Distance 348 ± 7 ly
(107 ± 2 pc)
Absolute magnitude (MV) −1.99[5]
Other designations
Kaus Media, Kaus Meridionalis, Media, δ Sagittarii, δ Sgr, Delta Sgr, 19 Sagittarii, CCDM J18210-2950A, CPD-30 5513, FK5 687, GC 25024, HD 168454, HIP 89931, HR 6859, IDS 18146-2952 A, PPM 268275, SAO 186681, WDS J18210-2950A.[6]

Delta Sagittarii (Delta Sgr, δ Sagittarii, δ Sgr) is a double star[6] in the southern zodiac constellation of Sagittarius. It has the traditional names Kaus Media, Kaus Meridionalis, and Media.The apparent visual magnitude of this star is +2.70,[2] making it easily visible to the naked eye. Parallax measurements place the distance at roughly 348 light-years (107 parsecs) from Earth.[1]

This is a giant star with a stellar classification K3 III.

It has three dim companions:[7]

  • a 14th magnitude star at a separation of 26 arcseconds,
  • a 15th magnitude star at a separation of 40 arcseconds, and
  • a 13th magnitude star at a separation of 58 arcseconds from the primary.

It is not certain that these stars form a physical system or whether they are merely aligned by chance.

Name and etymology[edit]

See also[edit]


  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:0708.1752free to read, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357 
  2. ^ a b c d Johnson, H. L.; et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory, 4 (99): 99, Bibcode:1966CoLPL...4...99J 
  3. ^ 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, 
  4. ^ Evans, D. S. (June 20–24, 1966), Batten, Alan Henry; Heard, John Frederick, eds., "The Revision of the General Catalogue of Radial Velocities", Determination of Radial Velocities and their Applications, University of Toronto: International Astronomical Union, 30: 57, Bibcode:1967IAUS...30...57E, retrieved 2009-09-10 
  5. ^ Elgarøy, Øystein; Engvold, Oddbjørn; Lund, Niels (March 1999), "The Wilson-Bappu effect of the MgII K line - dependence on stellar temperature, activity and metallicity", Astronomy and Astrophysics, 343: 222–228, Bibcode:1999A&A...343..222E 
  6. ^ a b "del Sgr -- Star in double system", SIMBAD, Centre de Données astronomiques de Strasbourg, retrieved 2012-01-11 
  7. ^ Dommanget, J.; Nys, O. (1994). "Catalogue des composantes d'etoiles doubles et multiples (CCDM) premiere edition - Catalogue of the components of double and multiple stars (CCDM) first edition". Com. de l'Observ. Royal de Belgique. 115: 1. Bibcode:1994CoORB.115....1D. 
  8. ^ "Sagittarius". Retrieved 30 August 2008. 
  9. ^ skywatchers Archived May 17, 2007, at the Wayback Machine.
  10. ^ a b Allen, R. H. (1963). Star Names: Their Lore and Meaning (Reprint ed.). New York: Dover Publications Inc. p. 355. ISBN 0-486-21079-0. Retrieved 2012-09-04. 
  11. ^ 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 (8): 435. Bibcode:1895MNRAS..55..429K. doi:10.1093/mnras/55.8.429. 
  12. ^ (Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 5 月 11 日

External links[edit]