Alpha Sagittae
 Location of α Sagittae (circled) |
|
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) |
|
|---|---|
| Constellation | Sagitta |
| Right ascension | 19h 40m 05.8s |
| Declination | +18° 00′ 50″ |
| Apparent magnitude (V) | +4.39 |
| Characteristics | |
| Spectral type | G1 II |
| Astrometry | |
| Radial velocity (Rv) | 1.72 ± 0.16 km/s |
| Proper motion (μ) |
RA: 15.09 ± 0.16 mas/yr Dec.: -19.65 ± 0.15 mas/yr |
| Parallax (π) | 7.67 ± 0.24mas |
| Distance | 430 ± 10 ly (130 ± 4 pc) |
| Absolute magnitude (MV) | −0.96 |
| Details | |
| Mass | 4.11 M☉ |
| Luminosity | 340 L☉ |
| Surface gravity (log g) | 3.11 cgs |
| Temperature | 5,333 K |
| Metallicity [Fe/H] | −0.15 dex |
| Age | 151 Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
Alpha Sagittae (α Sagittae, abbreviated Alpha Sge, α Sge), also named Sham, 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) 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.
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.)
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. The star's radius is roughly 20 times solar (R☉) while its mass is 4 times solar (M☉).
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