Gamma2 Sagittarii: Difference between revisions
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| url = http://deepsky.astroinfo.org/Sgr/ |
| url = http://deepsky.astroinfo.org/Sgr/ |
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| accessdate = 30 August 2008 |
| accessdate = 30 August 2008 |
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}}</ref><ref name="skywatchers">[http://www.flandrau.org/astronomy/skywatchers/picupclose.php?picid=89 skywatchers]{{ |
}}</ref><ref name="skywatchers">[http://www.flandrau.org/astronomy/skywatchers/picupclose.php?picid=89 skywatchers] {{wayback|url=http://www.flandrau.org/astronomy/skywatchers/picupclose.php?picid=89 |date=20070517140951 }}</ref> |
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**[[Delta Sagittarii|δ Sgr]] and [[Epsilon Sagittarii|ε Sgr]] were Akkadian ''Sin-nun‑tu'', or ''Si-nu-nu‑tum'', the Swallow.<ref name=allen1899/> |
**[[Delta Sagittarii|δ Sgr]] and [[Epsilon Sagittarii|ε Sgr]] were Akkadian ''Sin-nun‑tu'', or ''Si-nu-nu‑tum'', the Swallow.<ref name=allen1899/> |
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*In the catalogue of stars in the ''Calendarium'' of [[Al Achsasi al Mouakket]], this star was designated '''Aoul al Waridah''', which was translated into [[Latin]] as '''Prima τού al Warida''', meaning ''first going ostrich''.<ref>{{cite journal |
*In the catalogue of stars in the ''Calendarium'' of [[Al Achsasi al Mouakket]], this star was designated '''Aoul al Waridah''', which was translated into [[Latin]] as '''Prima τού al Warida''', meaning ''first going ostrich''.<ref>{{cite journal |
Revision as of 21:29, 12 January 2016
Observation data Epoch J2000.0 Equinox J2000.0 | |
---|---|
Constellation | Sagittarius |
Right ascension | 18h 05m 48.48810s[1] |
Declination | –30° 25′ 26.7235″[1] |
Apparent magnitude (V) | +2.98[2] |
Characteristics | |
Spectral type | K1 III[2] |
U−B color index | +0.77[3] |
B−V color index | +1.01[3] |
Astrometry | |
Radial velocity (Rv) | 22.0[2] km/s |
Proper motion (μ) | RA: –53.92[1] mas/yr Dec.: -180.90[1] mas/yr |
Parallax (π) | 33.67 ± 0.18 mas[1] |
Distance | 96.9 ± 0.5 ly (29.7 ± 0.2 pc) |
Details | |
Radius | 12[4] R☉ |
Surface gravity (log g) | 2.72[5] cgs |
Temperature | 4,760[5] K |
Metallicity [Fe/H] | –0.36[5] dex |
Other designations | |
Database references | |
SIMBAD | data |
Gamma Sagittarii (Gamma Sgr, γ Sagittarii, γ Sgr) is a 3rd-magnitude star in the zodiac constellation Sagittarius. The location of this star forms the tip of the arrow in the bow of Sagittarius the Centaur. It has the proper names Alnasl (Nasl, El Nasl), Nushaba (Nash) and Warida.[6]
This star is close enough to the Earth that its distance can be determined using parallax, yielding a value of about 96.9 light-years (29.7 parsecs). It has an apparent visual magnitude of +2.98,[2] making it the seventh brightest star in the constellation. A stellar classification of K1 III reveals that this is a giant star,[2] having expanded to an estimated 12 times the Sun's radius.[4] This means it has exhausted the hydrogen in its core and evolved away from the main sequence. The abundance of elements other than hydrogen and helium in this star, what astronomers term the star's metallicity,[5] is lower than in the Sun. Gamma Sagittarii has an effective temperature of 4,760 K,[5] compared to 5,778 K for the Sun.[8] It is this lower temperature that gives Gamma Sagittarii the orange hue that is a characteristic of K-type stars.
There is a fainter optical companion located about 50 arcminutes north of this star. It is magnitude 4.7 Cepheid variable star designated W Sagittarii.[9][10]
Name and etymology
- Alnasl is derived from the Arabic النصل al-naşl meaning "arrowhead".,[11] Nushaba is derived from the Arabic Zujj al-Nashshaba meaning the same as Alnasl.,[12] Warida is derived from النعم الوارد Al Naʽām al Wārid, the Going Ostriches, the asterism consisting this star, δ Sgr, ε Sgr and η Sgr.[12]
- This star, together with :
- In the catalogue of stars in the Calendarium of Al Achsasi al Mouakket, this star was designated Aoul al Waridah, which was translated into Latin as Prima τού al Warida, meaning first going ostrich.[15]
- In Chinese, 箕 (Jī), meaning Winnowing Basket, refers to an asterism consisting of γ Sagittarii, δ Sagittarii, ε Sagittarii and η Sagittarii. Consequently, γ Sagittarii itself is known as 箕宿一 (Jī Sù yī, English: the First Star of Winnowing Basket.)[16]
References
- ^ a b c d e 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
- ^ a b c d e Wielen, R.; et al. (1999), "Sixth Catalogue of Fundamental Stars (FK6). Part I. Basic fundamental stars with direct solutions", Veröff. Astron. Rechen-Inst. Heidelb, 35 (35), Astronomisches Rechen-Institut Heidelberg: 1, Bibcode:1999VeARI..35....1W
- ^ a b 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
- ^ a b Pasinetti-Fracassini, L. E.; et al. (February 2001), "Catalogue of Stellar Diameters (CADARS)", Astronomy and Astrophysics, 367 (2): 521–524, arXiv:astro-ph/0012289, Bibcode:2001A&A...367..521P, doi:10.1051/0004-6361:20000451
- ^ a b c d e McWilliam, Andrew (December 1990), "High-resolution spectroscopic survey of 671 GK giants. I - Stellar atmosphere parameters and abundances", Astrophysical Journal Supplement Series, 74: 1075–1128, Bibcode:1990ApJS...74.1075M, doi:10.1086/191527
- ^ a b Olcott, William Tyler (1907), A field book of the stars (2nd ed.), G. P. Putnam's sons, p. 136
- ^ "gam Sgr -- Variable Star", SIMBAD, Centre de Données astronomiques de Strasbourg, retrieved 2012-01-05
- ^ "The Colour of Stars", Australia Telescope, Outreach and Education, Commonwealth Scientific and Industrial Research Organisation, December 21, 2004, retrieved 2012-01-16
- ^ Kaler, James B., "ALNASL (Gamma-2 and Gamma-1=W Sagittarii)", Stars, University of Illinois, retrieved 2012-01-05
- ^ Burnham, Robert (1978), Burnham's celestial handbook: an observer's guide to the universe beyond the solar system, Dover books explaining science, vol. 3 (2nd ed.), Courier Dover Publications, p. 1560, ISBN 0-486-23673-0
- ^ Ridpath, Ian (1989), Star tales, James Clarke & Co., p. 113, ISBN 0-7188-2695-7
- ^ a b c 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.
- ^ "Sagittarius". deepsky.astroinfo.org. Retrieved 30 August 2008.
- ^ skywatchers Template:Wayback
- ^ 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. doi:10.1093/mnras/55.8.429.
- ^ Template:Zh icon AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 5 月 11 日