26 Draconis is a triple star system[12] in the constellation Draco, located 46 light years from the Sun. Two of the system components, A and B, form a spectroscopic binary that completes an orbit every 76 years. The composite spectral classification of the AB pair is G0V, which decomposes to individual spectral types F9V and K3V.[3] A 1962 study estimated the masses of these two stars as 1.30 and 0.83 times the mass of the Sun, respectively.[7] The stars are considered moderately metal-poor compared to the Sun, which means they have a lower proportion of elements other than hydrogen or helium.[9]
Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Draco |
Right ascension | 17h 34m 59.59363s[1] |
Declination | +61° 52′ 28.4006″[1] |
Apparent magnitude (V) | 5.236[2] |
Characteristics | |
Spectral type | G0Va (F9V + K3V)[3] |
U−B color index | +0.100[2] |
B−V color index | +0.595[2] |
Astrometry | |
Radial velocity (Rv) | –12.7[4] km/s |
Proper motion (μ) | RA: 277.02[1] mas/yr Dec.: –524.88[1] mas/yr |
Parallax (π) | 70.47 ± 0.37 mas[1] |
Distance | 46.3 ± 0.2 ly (14.19 ± 0.07 pc) |
Absolute magnitude (MV) | 4.58±0.011[5] |
Orbit[6] | |
Primary | 26 Dra A |
Companion | 26 Dra B |
Period (P) | 76.1 yr |
Semi-major axis (a) | 1.53″ |
Eccentricity (e) | 0.18 |
Inclination (i) | 104° |
Longitude of the node (Ω) | 151° |
Periastron epoch (T) | 1947 |
Argument of periastron (ω) (secondary) | 307° |
Details | |
Mass | 1.30/0.83[7] M☉ |
Surface gravity (log g) | 4.50[8] cgs |
Temperature | 6,000[8] K |
Metallicity [Fe/H] | -0.18[9] dex |
Rotational velocity (v sin i) | 10[10] km/s |
Age | 8.4–11.5[9] Gyr |
Other designations | |
AB: 26 Dra, HD 160269, HIP 86036, HR 6573, LHS 3305, LTT 15223, SAO 17546[11] | |
C: HIP 86037, GJ 685, LTT 15224 | |
Database references | |
SIMBAD | AB |
C |
The third component, GJ 685, is a red dwarf spectral classification of M0V. As of 1970, this star is separated by 737.9 arc seconds from the AB pair and they share a common proper motion.[13] The Star GJ 685 has one known planet orbit that was detected by radial velocity. [14]
Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
---|---|---|---|---|---|---|
b | 9.0+1.7−1.8 M🜨 | 0.1344 | 24.160+0.061−0.047 d | — | — | — |
The space velocity components of 26 Draconis are U = +36.5, V = −4.3 and W = −21.8 km/s.[15] This system is on an orbit through the Milky Way galaxy that has an eccentricity of 0.14, taking it as close as 23.1 kly (7.08 kpc) and as far as 30.4 kly (9.32 kpc) from the galactic core. The inclination of this orbit carries the star system as much as 0.75 kly (0.23 kpc) above the plane of the galactic disk.[16] This system may be a member of the Ursa Major moving group.[17]