Epsilon Draconis
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Draco |
| A | |
| Right ascension | 19h 48m 10.35046s |
| Declination | +70° 16′ 04.5491″ |
| Apparent magnitude (V) | 3.91 |
| B | |
| Right ascension | 19h 48m 10.54875s |
| Declination | +70° 16′ 07.5676″ |
| Apparent magnitude (V) | 6.80 |
| Characteristics | |
| A | |
| Evolutionary stage | red clump |
| Spectral type | G7IIIbFe-1 |
| U−B color index | +0.48 |
| B−V color index | +0.88 |
| B | |
| Spectral type | F6V |
| B−V color index | 0.57 |
| Astrometry | |
| A | |
| Radial velocity (Rv) | +2.89±0.11 km/s |
| Proper motion (μ) | RA: +79.486 mas/yr Dec.: +40.041 mas/yr |
| Parallax (π) | 21.3219±0.1256 mas |
| Distance | 153.0 ± 0.9 ly (46.9 ± 0.3 pc) |
| B | |
| Proper motion (μ) | RA: +86.898 mas/yr Dec.: +37.126 mas/yr |
| Parallax (π) | 21.3808 ± 0.0403 mas |
| Distance | 152.5 ± 0.3 ly (46.77 ± 0.09 pc) |
| Details | |
| A | |
| Mass | 1.20±0.08, 1.76+0.29 −0.23 M☉ |
| Radius | 10.41±0.29 R☉ |
| Luminosity | 63.1 L☉ |
| Surface gravity (log g) | 2.61 cgs |
| Temperature | 4,966±41 K |
| Metallicity | = -0.31 |
| Metallicity [Fe/H] | −0.30 dex |
| Rotational velocity (v sin i) | 2.25±0.56 km/s |
| Age | 2.6+1.8 −1.6 Gyr |
| B | |
| Radius | 1.16 R☉ |
| Luminosity | 2.814 L☉ |
| Temperature | 6,936 K |
| Other designations | |
| Tyl, ε Dra, 63 Dra, AG+70°689, BD+69°1070, GC 27471, HD 188119, HIP 97433, HR 7582, SAO 9540, CCDM J19482+7016AB, PLX 4689, IRAS 19483+7008, 2MASS J19481035+7016045 | |
| Database references | |
| SIMBAD | data |
![{\displaystyle {\begin{smallmatrix}\left[{\ce {M}}/{\ce {H}}\right]\end{smallmatrix}}}](./d9a106d03666c72cc54c1dff07a5637d3adda9a1.svg)
Epsilon Draconis, Latinized from ε Draconis, is a binary star in the constellation Draco, with a combined apparent magnitude of 3.84, it is the eleventh-brightest star in this rather faint constellation. This star along with Delta Draconis (Altais), Pi Draconis and Rho Draconis forms an asterism known as Al Tāis, meaning "the Goat". The distance to this system has been calculated to be about 150 light-years, based on stellar parallax measurements.
In Chinese astronomy, 天廚 (Tiān Chú), meaning the Celestial Kitchen, refers to an asterism consisting of Epsilon Draconis, Delta Draconis, Sigma Draconis, Rho Draconis, 64 Draconis and Pi Draconis. Consequently, the Chinese name for Epsilon Draconis itself is 天廚三 (Tiān Chú sān, English: the Third Star of the Celestial Kitchen.) Most authors do not use a traditional name for this star, using instead the Bayer designation; but Bečvář (1951) listed it as Tyl /ˈtɪl/.