Alpha Sagittae

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α Sagittae
Sagitta constellation map.svg
Red circle.svg
Location of α Sagittae (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Sagitta
Right ascension 19h 40m 05.8s[1]
Declination +18° 00′ 50″[1]
Apparent magnitude (V) +4.39[2]
Spectral type G1 II[2]
Radial velocity (Rv)1.72 ± 0.16[3] km/s
Proper motion (μ) RA: 15.09 ± 0.16[1] mas/yr
Dec.: -19.65 ± 0.15[1] mas/yr
Parallax (π)7.67 ± 0.24[1] mas
Distance430 ± 10 ly
(130 ± 4 pc)
Absolute magnitude (MV)−0.96[4]
Mass4.11[5] M
Luminosity340[2] L
Surface gravity (log g)3.11[2] cgs
Temperature5,333[2] K
Metallicity [Fe/H]−0.15[2] dex
Age151[5] Myr
Other designations
Sham, Alsahm, α Sagittae, α Sge, Alpha Sge, 5 Sagittae, BD+17°4042, CCDM J19401+1801A, GC 27215, HD 185758, HIP 96757, HR 7479, IDS 19356+1747 A, PPM 136737, SAO 105120, WDS J19401+1801A
Database references

Alpha Sagittae (α Sagittae, abbreviated Alpha Sge, α Sge), also named Sham,[6] is a star in the constellation of Sagitta. Based upon parallax measurements taken during the Hipparcos mission, it is approximately 430 light-years from the Sun.


α Sagittae (Latinised to Alpha Sagittae) is the star's Bayer designation.

It bore the traditional name Sham (or Alsahm), which derives from the Arabic word سهم sahm, meaning "arrow", the name formerly having been applied to the whole constellation. In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)[7] to catalogue and standardize proper names for stars. The WGSN approved the name Sham for this star on 12 September 2016 and it is now so included in the List of IAU-approved Star Names.[6]

In Chinese, 左旗 (Zuǒ Qí), meaning Left Flag, refers to an asterism consisting of Alpha Sagittae, Beta Sagittae, Delta Sagittae, Zeta Sagittae, Gamma Sagittae, 13 Sagittae, 11 Sagittae, 14 Sagittae and Rho Aquilae. Consequently, Alpha Sagittae itself is known as 左旗一 (Zuǒ Qí yī, English: the First Star of Left Flag).[8]


Alpha Sagittae is a yellow bright giant star of apparent magnitude +4.38 and spectral class G1 II. It has a luminosity of 340 L with a surface temperature of 5,333 K.[2] The star's radius is roughly 20 R while its mass is 4 M.


  1. ^ a b c d e van Leeuwen, F. (2007). "Validation of the New Hipparcos Reduction". Astronomy and Astrophysics. 474 (2): 653–64. arXiv:0708.1752Freely accessible. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. 
  2. ^ a b c d e f g Mallik, Sushma V. (December 1999), "Lithium abundance and mass", Astronomy and Astrophysics, 352: 495–507, Bibcode:1999A&A...352..495M 
  3. ^ Soubiran, C.; Bienaymé, O.; Mishenina, T. V.; Kovtyukh, V. V. (2008). "Vertical distribution of Galactic disk stars. IV. AMR and AVR from clump giants". Astronomy and Astrophysics. 480: 91. arXiv:0712.1370Freely accessible. Bibcode:2008A&A...480...91S. doi:10.1051/0004-6361:20078788. 
  4. ^ Kovtyukh, V. V.; Gorlova, N. I.; Belik, S. I. (2012). "Accurate luminosities from the oxygen λ7771-4 Å triplet and the fundamental parameters of F-G supergiants". Monthly Notices of the Royal Astronomical Society. 423 (4): 3268. arXiv:1204.4115Freely accessible. Bibcode:2012MNRAS.423.3268K. doi:10.1111/j.1365-2966.2012.21117.x. 
  5. ^ a b Takeda, Yoichi; Sato, Bun'ei; Murata, Daisuke (2008). "Stellar Parameters and Elemental Abundances of Late-G Giants". Publications of the Astronomical Society of Japan. 60 (4): 781. arXiv:0805.2434Freely accessible. Bibcode:2008PASJ...60..781T. doi:10.1093/pasj/60.4.781. 
  6. ^ a b "Naming Stars". Retrieved 16 December 2017. 
  7. ^ IAU Working Group on Star Names (WGSN), International Astronomical Union, retrieved 22 May 2016. 
  8. ^ (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 3 日