Gamma Cygni
 Location of γ Cyg (circled) |
|
| Observation data Epoch J2000 Equinox J2000 |
|
|---|---|
| Constellation | Cygnus |
| Right ascension | 20h 22m 13.70184s |
| Declination | +40° 15′ 24.0450″ |
| Apparent magnitude (V) | 2.23 |
| Characteristics | |
| Spectral type | F8 Iab |
| U−B color index | +0.54 |
| B−V color index | +0.67 |
| Variable type | suspected |
| Astrometry | |
| Radial velocity (Rv) | -7.5 km/s |
| Proper motion (μ) |
RA: +2.39 mas/yr Dec.: -0.91 mas/yr |
| Parallax (π) | 1.78 ± 0.27mas |
| Distance | approx. 1,800 ly (approx. 560 pc) |
| Absolute magnitude (MV) | −4.54 |
| Details | |
| Mass | 12.11±0.71 M☉ |
| Radius | 150±80 R☉ |
| Luminosity (bolometric) | 33,023 L☉ |
| Surface gravity (log g) | 1.02±0.10 cgs |
| Temperature | 5,790±100 K |
| Metallicity [Fe/H] | +0.02 dex |
| Rotational velocity (v sin i) | 15 km/s |
| Age | 12 Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
Gamma Cygni (γ Cygni, abbreviated Gamma Cyg, γ Cyg), also named Sadr, is a star in the northern constellation of Cygnus, forming the intersection of an asterism of five stars called the Northern Cross.
γ Cygni (Latinised to Gamma Cygni) is the star's Bayer designation.
It bore the traditional name Sadr (also spelled Sadir or Sador), derived from the Arabic صدر ṣadr "chest", the same word which gave rise to the star Schedar (Alpha Cassiopeiae). 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 Sadr for this star on 21 August 2016 and it is now so entered in the IAU Catalog of Star Names.
In the catalogue of stars in the Calendarium of Al Achsasi al Mouakket, this star was designated Sadr al Dedjadjet, (صدر الدجاجة / ṣadr al-dajājati), which was translated into Latin as Pectus Gallinǣ, meaning the hen's chest.
In Chinese, 天津 (Tiān Jīn), meaning Celestial Ford, refers to an asterism consisting of Gamma Cygni, Delta Cygni, 30 Cygni, Alpha Cygni, Nu Cygni, Tau Cygni, Upsilon Cygni, Zeta Cygni and Epsilon Cygni. Consequently, Gamma Cygni itself is known as 天津一 (Tiān Jīn yī, English: the First Star of Celestial Ford.).
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