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
Distance 430 ± 10 ly
(130 ± 4 pc)
Absolute magnitude (MV) −0.96[4]
Mass 4.11[5] M
Luminosity 340[2] L
Surface gravity (log g) 3.11[2] cgs
Temperature 5,333[2] K
Metallicity [Fe/H] −0.15[2] dex
Age 151[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.


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 entered in the IAU Catalog of 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 four times more massive and 340 times brighter than the Sun. It is a yellow-bright giant star of apparent magnitude +4.38 and spectral class G1 II about 430 ± 10 light-years from Earth. It has a luminosity 340 times that of the Sun with a surface temperature of 5,333 K.[2] The star's radius is roughly 20 times solar (R) while its mass is 4 times solar (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. 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 "IAU Catalog of Star Names". Retrieved 28 July 2016. 
  7. ^ IAU Working Group on Star Names (WGSN), International Astronomical Union, retrieved 22 May 2016. 
  8. ^ (Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 3 日