Omega Sagittarii

Omega Sagittarii

Location of ω Sagittarii (circled)
Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Sagittarius
Right ascension	19^h 55^m 50.3577^s[1]
Declination	−26° 17′ 58.223″[1]
Apparent magnitude (V)	4.70[1]
Characteristics
Spectral type	G5IV[1]
U−B color index	+0.32[2]
B−V color index	+0.75[2]
R−I color index	+0.37[2]
Astrometry
Radial velocity (Rv)	−21.0 ± 0.9[1] km/s
Proper motion (μ)	RA: 203.96[1] mas/yr Dec.: 74.40[1] mas/yr
Parallax (π)	42.03 ± 0.94[1] mas
Distance	78 ± 2 ly (23.8 ± 0.5 pc)
Absolute magnitude (MV)	2.82[3]
Details
Radius	1.1[4] R☉
Temperature	5400[5] K
Metallicity	[Fe/H] = 0.00[5]
Rotational velocity (v sin i)	2[5] km/s
Age	2.9 (2.8 to 3.0) × 10^9[5] years
Other designations
ω Sagittarii, ω Sgr, Omega Sgr, 58 Sgr, CPD−26 6880, GC 27583, HD 188376, HIP 98066, HR 7597, PPM 270451, SAO 188722.[1]
Database references
SIMBAD	data

Omega Sagittarii (Omega Sgr, ω Sagittarii, ω Sgr) is a G-type subgiant star in the constellation of Sagittarius.^[1] It has an apparent visual magnitude of approximately 4.70.

Name and etymology

• This star, together with :
  • 60 Sgr, 62 Sgr and 59 Sgr, consisting the asterism Terebellum^[6] According to the catalogue of stars in the Technical Memorandum 33-507 - A Reduced Star Catalog Containing 537 Named Stars, Terebellum was originally the title for four stars: ω Sgr as Terebellum I, 59 Sgr as Terebellum II, 60 Sgr as Terebellum III and 62 Sgr as Terebellum IV .^[7]
  • ν Sgr, ψ Sgr, τ Sgr, 60 Sgr and ζ Sgr were Al Udḥiyy, the Ostrich's Nest.^[6]
• In Chinese, 狗國 (Gǒu Guó), meaning Dog Territory, refers to an asterism consisting of ω Sagittarii, 60 Sgr, 62 Sgr and 59 Sgr. Consequently, ω Sagittarii itself is known as 狗國一 (Gǒu Guó yī, English: the First Star of Dog Territory.)^[8]

References

1. LTT 7872 -- High proper-motion Star, database entry, SIMBAD. Accessed on line November 19, 2009.
2. HR 7597, database entry, The Bright Star Catalogue, 5th Revised Ed. (Preliminary Version), D. Hoffleit and W. H. Warren, Jr., CDS ID V/50. Accessed on line November 19, 2009.
3. From apparent magnitude and parallax.
4. HD 188376, database entry, Catalog of Apparent Diameters and Absolute Radii of Stars (CADARS), 3rd edition, L. E. Pasinetti-Fracassini, L. Pastori, S. Covino, and A. Pozzi, CDS ID II/224. Accessed on line November 19, 2009.
5. HD 188376, database entry, The Geneva-Copenhagen Survey of Solar neighbourhood, J. Holmberg et al., 2007, CDS ID V/117A. Accessed on line November 19, 2009.
6. 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.
7. Jack W. Rhoads - Technical Memorandum 33-507-A Reduced Star Catalog Containing 537 Named Stars, Jet Propulsion Laboratory, California Institute of Technology; November 15, 1971
8. (Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 2 日