Delta Sagittarii
| |
| 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 | |
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
- 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 Thani al Waridah, meaning second of Warida.[11]
- In Chinese, 箕 (Jī), 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.)[12]
- In the Hindu system of astrology, this star is also called "Purvashada Nakshatra".
See also
References
- 1 2 3 4 5 6 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
- 1 2 3 4 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
- ↑ 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:1982mcts.book.....H
- ↑ 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
- ↑ 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
- 1 2 "del Sgr -- Star in double system", SIMBAD (Centre de Données astronomiques de Strasbourg), retrieved 2012-01-11
- ↑ 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.
- ↑ "Sagittarius". deepsky.astroinfo.org. Retrieved 30 August 2008.
- ↑ skywatchers Archived May 17, 2007, at the Wayback Machine.
- 1 2 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.
- ↑ 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.
- ↑ (Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 5 月 11 日
External links
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