Epoch J2000.0 Equinox J2000.0
|Right ascension||19h 04m 40.98s |
|Declination||−21° 44′ 29.4″ |
|Apparent magnitude (V)||+ 3.771|
|Proper motion (μ)||RA: 76.35 ± 0.31  mas/yr
Dec.: −58.12 ± 0.18  mas/yr
|Parallax (π)||22.96 ± 0.24 mas|
|Distance||142 ± 1 ly
(43.6 ± 0.5 pc)
|Absolute magnitude (MV)||0.625|
|Surface gravity (log g)||2.66 cgs|
|Metallicity [Fe/H]||−0.04 dex|
Omicron Sagittarii (Omicron Sgr, ο Sagittarii, ο Sgr) is a binary star in the constellation Sagittarius. ο Sagittarii is located 142 light years from Earth and is a spectral type K0 orange giant with an apparent magnitude of +3.77. It has a faint, 13th magnitude companion, ο Sagittarii B, 36 arc seconds away.
Because it is close to the ecliptic, ο Sagittarii can be occulted by the Moon and very rarely by planets. The last occultation of ο Sagittarii by a planet took place on 24 December 1937, when it was occulted by Mercury.
Name and etymology
- In Chinese, 建 (Jiàn), meaning Establishment, refers to an asterism consisting of ο Sagittarii ξ² Sagittarii, π Sagittarii, 43 Sagittarii, ρ¹ Sagittarii and υ Sagittarii. Consequently, ο Sagittarii itself is known as 建二 (Jiàn èr, English: the Second Star of Establishment.)
- van Leeuwen, F. (2007). "HIP 93683". Hipparcos, the New Reduction. Retrieved 2009-12-04.
- Liu, Y. J.; et al. (2007), "The abundances of nearby red clump giants", Monthly Notices of the Royal Astronomical Society, 382 (2): 553–66, Bibcode:2007MNRAS.382..553L, doi:10.1111/j.1365-2966.2007.11852.x.
- (Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 5 月 11 日
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