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]
Characteristics
Spectral type K3 III[3]
U−B color index +1.55[2]
B−V color index +1.38[2]
Astrometry
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]
Details
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:[citation needed]

  • 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]

  • The names Kaus Media, Kaus Meridionalis, and Media, are come from the Arabic قوس qaws 'bow' and Latin media 'middle'.
  • This star, together with :
  • In the catalogue of stars in the Calendarium of Al Achsasi al Mouakket, this star was designated Thanih al Waridah, which was translated into Latin as Secunda τού al Warida, meaning second going ostrich.[10]
  • In Chinese, (), meaning Winnowing Basket, refers to an asterism consisting of δ Sagittarii γ Sagittarii, ε Sagittarii and η Sagittarii. Consequently, δ Sagittarii itself is known as 箕宿二 (Jī Sù èr, English: the Second Star of Winnowing Basket.)[11]
  • In the Hindu system of astrology, this star is also called "Purvashada Nakshatra".

See also[edit]

References[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:0708.1752, 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), Bibcode:1966CoLPL...4...99J 
  3. ^ Houk, Nancy (1979), Michigan catalogue of two-dimensional spectral types for the HD stars 3, Ann Arbor, Michigan: Dept. of Astronomy, University of Michigan, Bibcode:1982mcts.book.....H 
  4. ^ 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, University of Toronto: International Astronomical Union, 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. ^ "Sagittarius". deepsky.astroinfo.org. Retrieved 30 August 2008. 
  8. ^ skywatchers[dead link]
  9. ^ 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. 
  10. ^ 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: 435. Bibcode:1895MNRAS..55..429K. 
  11. ^ (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]