Astronomy:26 Draconis
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Short description: Star in the constellation Draco
| Observation data {{#ifeq:J2000|J2000.0 (ICRS)|Epoch J2000.0 Equinox J2000.0 (ICRS)| Epoch J2000 [[Astronomy:Equinox (celestial coordinates)|Equinox J2000}} | |
|---|---|
| Constellation | Draco |
| AB | |
| Right ascension | 17h 34m 59.62474s[1] |
| Declination | +61° 52′ 28.2418″[1] |
| Apparent magnitude (V) | 5.236[2] |
| C | |
| Right ascension | 17h 35m 34.47852s[3] |
| Declination | +61° 40′ 53.6281″[3] |
| Apparent magnitude (V) | 9.97[4] |
| Characteristics | |
| AB | |
| Evolutionary stage | main sequence[1] |
| Spectral type | G0Va (F9V + K3V)[5] |
| U−B color index | +0.100[2] |
| B−V color index | +0.595[2] |
| C | |
| Evolutionary stage | main sequence[3] |
| Spectral type | M0.5V[4] |
| B−V color index | +1.48[4] |
| Astrometry | |
| AB | |
| Radial velocity (Rv) | −15.72±0.33[1] km/s |
| Proper motion (μ) | RA: 236.247[1] mas/yr Dec.: −466.111[1] mas/yr |
| Parallax (π) | 69.2832 ± 0.2004[1] mas |
| Distance | 47.1 ± 0.1 ly (14.43 ± 0.04 pc) |
| Absolute magnitude (MV) | 4.58±0.011[6] |
| C | |
| Radial velocity (Rv) | −15.53±0.16[3] km/s |
| Proper motion (μ) | RA: 261.923 mas/yr Dec.: −514.499 mas/yr |
| Parallax (π) | 69.8921 ± 0.0153[3] mas |
| Distance | 46.67 ± 0.01 ly (14.308 ± 0.003 pc) |
| Orbit[7] | |
| 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 | |
| AB | |
| Mass | 1.30/0.83[8] M☉ |
| Surface gravity (log g) | 4.50[9] cgs |
| Temperature | 6,000[9] K |
| Metallicity [Fe/H] | −0.18[10] dex |
| Rotational velocity (v sin i) | 10[11] km/s |
| Age | 8.4–11.5[10] Gyr |
| C | |
| Mass | 0.55±0.06[4] M☉ |
| Radius | 0.54±0.05[4] R☉ |
| Surface gravity (log g) | 4.72±0.05[4] cgs |
| Temperature | 3816±69[4] K |
| Rotation | 18.15+0.15 −0.16 d[4] |
| Rotational velocity (v sin i) | 1.33±0.42[4] km/s |
| Other designations | |
| AB: 26 Dra, BD+61 1678, GJ 684, HD 160269, HIP 86036, HR 6573, SAO 17546, LHS 3305, LTT 15223[12] | |
| C: GJ 685, HIP 86087, G 226-66, LHS 3306, LTT 15224[13] | |
| Database references | |
| SIMBAD | A |
| B | |
| C | |
26 Draconis is a triple star system[14] in the constellation Draco, located 47 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.[5] A 1962 study estimated the masses of these two stars as 1.30 and 0.83 times the mass of the Sun, respectively.[8] 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.[10]
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]
Gliese 685
The third component, GJ 685, is a red dwarf with 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.[18] The star GJ 685 has one known planet in orbit that was detected by radial velocity.[4]
| 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+0.0052 −0.0051 |
24.160+0.061 −0.047 |
— | — | — |
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940 Gaia DR3 record for this source at VizieR.
- ↑ 2.0 2.1 2.2 Oja, T. (1986), "UBV photometry of stars whose positions are accurately known. III", Astronomy and Astrophysics Supplement Series 65 (2): 405–4, Bibcode: 1986A&AS...65..405O.
- ↑ 3.0 3.1 3.2 3.3 3.4 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940 Gaia DR3 record for this source at VizieR.
- ↑ 4.00 4.01 4.02 4.03 4.04 4.05 4.06 4.07 4.08 4.09 4.10 Pinamonti, M. et al. (May 2019). "The HADES RV programme with HARPS-N at TNG. XI. GJ 685 b: a warm super-Earth around an active M dwarf". Astronomy & Astrophysics 625: A126. doi:10.1051/0004-6361/201834969. Bibcode: 2019A&A...625A.126P.
- ↑ 5.0 5.1 Edwards, T. W. (April 1976), "MK classification for visual binary components", Astronomical Journal 81: 245–249, doi:10.1086/111879, Bibcode: 1976AJ.....81..245E
- ↑ Park, Sunkyung et al. (2013), "Wilson-Bappu Effect: Extended to Surface Gravity", The Astronomical Journal 146 (4): 73, doi:10.1088/0004-6256/146/4/73, Bibcode: 2013AJ....146...73P.
- ↑ "Sixth Catalog of Orbits of Visual Binary Stars". United States Naval Observatory. http://www.usno.navy.mil/USNO/astrometry/optical-IR-prod/wds/orb6. Retrieved 25 March 2017.
- ↑ 8.0 8.1 Upgren, A. R. (October 1962). "Parallax and orbital motion of the triple system 26 Draconis from photographs taken with the Sproul 24-inch refractor". Astronomical Journal 67: 539–543. doi:10.1086/108760. Bibcode: 1962AJ.....67..539U.
- ↑ 9.0 9.1 Luck, R. Earle; Heiter, Ulrike (June 2006). "Dwarfs in the Local Region". The Astronomical Journal 131 (6): 3069–3092. doi:10.1086/504080. Bibcode: 2006AJ....131.3069L.
- ↑ 10.0 10.1 10.2 Makarov, V. V.; Zacharias, N.; Hennessy, G. S. (November 2008). "Common Proper Motion Companions to Nearby Stars: Ages and Evolution". The Astrophysical Journal 687 (1): 566–578. doi:10.1086/591638. Bibcode: 2008ApJ...687..566M.
- ↑ Bernacca, P. L.; Perinotto, M. (1970). "A catalogue of stellar rotational velocities". Contributi Osservatorio Astronomico di Padova in Asiago 239 (1): 1. Bibcode: 1970CoAsi.239....1B.
- ↑ "HD 160269". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=HD+160269.
- ↑ "GJ 685". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=GJ+685.
- ↑ Greaves, J. S.; Wyatt, M. C. (November 2003). "Some anomalies in the occurrence of debris discs around main-sequence A and G stars". Monthly Notices of the Royal Astronomical Society 345 (4): 1212–1222. doi:10.1046/j.1365-2966.2003.07037.x. Bibcode: 2003MNRAS.345.1212G.
- ↑ Soderblom, David R.; Mayor, Michel (January 1993). "Stellar kinematic groups. I - The Ursa Major group". Astronomical Journal 105 (1): 226–249. doi:10.1086/116422. Bibcode: 1993AJ....105..226S.
- ↑ Holmberg, J.; Nordström, B.; Andersen, J. (July 2009). "The Geneva-Copenhagen survey of the solar neighbourhood. III. Improved distances, ages, and kinematics". Astronomy and Astrophysics 501 (3): 941–947. doi:10.1051/0004-6361/200811191. Bibcode: 2009A&A...501..941H.
- ↑ Greaves, J. S.; Wyatt, M. C.; Bryden, G. (August 2009). "Debris discs around nearby solar analogues". Monthly Notices of the Royal Astronomical Society 397 (2): 757–762(6). doi:10.1111/j.1365-2966.2009.15048.x. Bibcode: 2009MNRAS.397..757G.
- ↑ Lépine, Sébastien; Bongiorno, Bethany (2007). "New Distant Companions to Known Nearby Stars. II. Faint Companions of Hipparcos Stars and the Frequency of Wide Binary Systems". The Astronomical Journal 133 (3): 889–905. doi:10.1086/510333. Bibcode: 2007AJ....133..889L.
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