Sigma Sagittarii
Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Sagittarius |
Right ascension | 18h 55m 15.92650s[1][2] |
Declination | –26° 17′ 48.2068″[1][2] |
Apparent magnitude (V) | 2.05[3] |
Characteristics | |
Spectral type | B2.5 V[4] |
U−B color index | –0.761[5] |
B−V color index | –0.204[5] |
Absolute magnitude (MV) | −2.17[6] |
Details | |
Myr | |
J18553-2618Aa,Ab | |
Database references | |
SIMBAD | data |
Sigma Sagittarii, Latinized from σ Sagittarii; formally named Nunki /ˈnʌŋki/,[13][14] is the second-brightest star in the constellation of Sagittarius. It has an apparent magnitude of +2.05,[3] making it readily visible to the naked eye. The distance to this star, determined using parallax measurements from the Hipparcos astrometry satellite,[15] yields a value of approximately 228 light-years (70 parsecs) from the Sun.[1][2]
Properties
Sigma Sagittarii has a
It has a 10th magnitude optical companion located 5.2
It is 3.45 degrees south of the ecliptic, so it can be occulted by the Moon and rarely by planets. The last occultation by a planet took place on November 17, 1981, when it was occulted by Venus.[19] This is the brightest star that can be principally occulted by an exterior planet between 5000 BC and 5000 AD. However, only Mars can do this, and only rarely; the last time was on September 3, 423.[citation needed]
Nomenclature
σ Sagittarii (Latinised to Sigma Sagittarii) is the star's Bayer designation. In his Uranometria star atlas, Johann Bayer placed this star in the fourth magnitude class, although it is a second-magnitude star by modern measurements.[citation needed]
It bore the traditional name of Nunki, which was an
This star, together with :
- Gamma Sagittarii, Delta Sagittarii, Epsilon Sagittarii, Zeta Sagittarii, Lambda Sagittarii, Tau Sagittarii and Phi Sagittarii, comprised the Teapot asterism.[22]
- Phi Sagittarii, Zeta Sagittarii, Chi Sagittarii and Tau Sagittarii were the Arabic Al Naʽām al Ṣādirah (النعم السادرة), the Returning Ostriches.[23]
Zeta Sagittarii and Pi Sagittarii may have been the Akkadian Gu-shi-rab‑ba, the Yoke of the Sea.[23]
In the catalogue of stars in the Calendarium of Al Achsasi al Mouakket, this star was designated Thanih al Sadirah, which was translated into Latin as Secunda τού al Sadirah, meaning second returning ostrich.[24]
In Chinese, 斗 (Dǒu), meaning Dipper, refers to an asterism consisting of Sigma Sagittarii, Phi Sagittarii, Lambda Sagittarii,
References
- ^ Bibcode:1997A&A...323L..49P
- ^ ISSN 0004-6361.
- ^ Bibcode:1999VeARI..35....1W
- ^ Bibcode:1982mcts.book.....H
- ^ doi:10.1086/190168
- S2CID 119257644.
- ^ S2CID 118629873
- ^ S2CID 14969137
- doi:10.1086/340590
- ^ Paul Kunitzsch [in German] (1959). Arabische Sternnamen in Europa. Wiesbaden: Otto Harrassowitz. p. 137. Retrieved 2020-08-30.
- ISBN 9780486318035. Retrieved 2020-08-30.
- Bibcode:1944PA.....52....8D.
- ^ a b "Naming Stars". IAU.org. Retrieved 16 December 2017.
- ISBN 978-3-642-11601-8
- ^ James B. Kaler, "NUNKI (Sigma Sagatarii)", Stars, University of Illinois, retrieved 2012-01-31
- doi:10.1086/173683
- doi:10.1086/323920.
- Bibcode:1981JBAA...91..148K.
- ^ Allen, Richard Hinckley, Star Names, their lore and meaning, p. 359
- ^ IAU Working Group on Star Names (WGSN), International Astronomical Union, retrieved 22 May 2016.
- ^ "Teapot". constellation-guide.com. Retrieved 2017-05-13.
- ^ ISBN 0-486-21079-0. Retrieved 2012-09-04.
- .
- ^ (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 5 月 11 日