59 Draconis
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Draco[1] |
| Right ascension | 19h 09m 09.88146s[2] |
| Declination | +76° 33′ 37.8138″[2] |
| Apparent magnitude (V) | 5.11[1] |
| Characteristics | |
| Evolutionary stage | main sequence[2] |
| Spectral type | A9V[3] |
| B−V color index | 0.308[1] |
| Variable type | γ Dor?[3] |
| Astrometry | |
| Radial velocity (Rv) | −3.77±0.50[2] km/s |
| Proper motion (μ) | RA: +52.390 mas/yr[2] Dec.: −119.469 mas/yr[2] |
| Parallax (π) | 36.5363±0.1299 mas[2] |
| Distance | 89.3 ± 0.3 ly (27.37 ± 0.10 pc) |
| Absolute magnitude (MV) | 2.93[1] |
| Orbit[3] | |
| Period (P) | 28.44±0.01 d |
| Semi-major axis (a) | 0.22 AU |
| Eccentricity (e) | 0.20±0.01 |
| Periastron epoch (T) | 2453244.3±0.3 JD |
| Argument of periastron (ω) (secondary) | 56±4° |
| Semi-amplitude (K1) (primary) | 1.20±0.02 km/s |
| Details | |
| A | |
| Mass | 1.447+0.014 −0.015[4] M☉ |
| Radius | 1.488+0.031 −0.033[4] R☉ |
| Luminosity | 4.861+0.285 −0.290[4] L☉ |
| Surface gravity (log g) | 4.18±0.21[5] cgs |
| Temperature | 7053±194[5] K |
| Rotational velocity (v sin i) | 53.0±1.1[5] km/s |
| Age | 436+156 −203[4] Myr |
| B | |
| Mass | ≥25[3] MJup |
| Other designations | |
| 59 Dra, NSV 11824, BD+76 717, GC 26484, GJ 9649, GJ 748.1, HD 180777, HIP 94083, HR 7312, SAO 9341, PPM 10093, PLX 4497[6] | |
| Database references | |
| SIMBAD | data |
59 Draconis is a star with a likely brown dwarf companion, located 89.3 light-years (27.4 parsecs) away in the constellation Draco. With an apparent magnitude of 5.1, it is faintly visible to the naked eye under good viewing conditions. In Chinese astronomy, this star is known as Tiānzhùsì (天柱四), meaning it is the fourth star of the asterism Tiānzhù (天柱, Celestial Pillar).[8]
The stellar classification of 59 Draconis is A9V,[3] indicating that it is an A-type main-sequence star that is generating energy through hydrogen fusion at its core. Other sources classify it as A7V[9] or F0Vs.[1] It has a similar chemical abundance to the Sun.[5] The star is listed as a suspected variable,[10] with pulsations resembling those of Gamma Doradus stars.[3] It is a candidate member of the Ursa Major Moving Group stream,[11][4] though a 2020 study listed its membership probability as only 33%.[12] It appears to be rotating with an inclination of about 28° to the plane of the sky.[4]
The detection of a companion via Doppler spectroscopy was announced in 2006.[3] This object orbits with a period of 28.4 days and has a minimum mass of 25 MJ, in the range of brown dwarfs. Since the inclination of the orbit is unknown, the true mass cannot be determined, and it remains possible that it is a star rather than a brown dwarf.[3] Hipparcos astrometry has set an upper limit on its mass of 0.27 M☉.[13] If confirmed as a brown dwarf, it is within the brown dwarf desert, a range of orbits where few brown dwarfs are found.[3]
References
- ^ a b c d e Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331. arXiv:1108.4971. Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015. XHIP record for this object at VizieR.
- ^ a b c d e f Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
- ^ a b c d e f g h i Galland, F.; Lagrange, A.-M.; et al. (June 2006). "Extrasolar planets and brown dwarfs around A-F type stars. IV. A candidate brown dwarf around the A9V pulsating star HD 180777". Astronomy and Astrophysics. 452 (2): 709–714. arXiv:astro-ph/0602592. Bibcode:2006A&A...452..709G. doi:10.1051/0004-6361:20054079.
- ^ a b c d e f Jones, Jeremy; White, R. J.; et al. (November 2015). "The Ages of A-Stars. I. Interferometric Observations and Age Estimates for Stars in the Ursa Major Moving Group". The Astrophysical Journal. 813 (1): 58. arXiv:1508.05643. Bibcode:2015ApJ...813...58J. doi:10.1088/0004-637X/813/1/58.
- ^ a b c d Saffe, C.; Miquelarena, P.; et al. (March 2021). "Chemical analysis of early-type stars with planets". Astronomy & Astrophysics. 647: A49. arXiv:2101.04416. Bibcode:2021A&A...647A..49S. doi:10.1051/0004-6361/202040132.
- ^ "* 59 Dra". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 18 June 2025.
- ^ Yi, Shitong (April 1981). 中西对照恒星图表 [Atlas Comparing Chinese and Western Star Maps and Catalogues] (in Chinese). 科学出版社.
- ^ Stellarium, citing Yi Shitong, 1981[7]
- ^ van Belle, Gerard T.; von Braun, Kaspar (April 2009). "Directly Determined Linear Radii and Effective Temperatures of Exoplanet Host Stars". The Astrophysical Journal. 694 (2): 1085–1098. arXiv:0901.1206. Bibcode:2009ApJ...694.1085V. doi:10.1088/0004-637X/694/2/1085.
- ^ "NSV 11824". International Variable Star Index. AAVSO. Retrieved 29 June 2025.
- ^ King, Jeremy R.; Villarreal, Adam R.; et al. (April 2003). "Stellar Kinematic Groups. II. A Reexamination of the Membership, Activity, and Age of the Ursa Major Group". The Astronomical Journal. 125 (4): 1980–2017. Bibcode:2003AJ....125.1980K. doi:10.1086/368241.
- ^ Ujjwal, K.; Kartha, Sreeja S.; et al. (April 2020). "Analysis of Membership Probability in Nearby Young Moving Groups with Gaia DR2". The Astronomical Journal. 159 (4): 166. arXiv:2002.04801. Bibcode:2020AJ....159..166U. doi:10.3847/1538-3881/ab76d6.
- ^ Sahlmann, J.; Ségransan, D.; et al. (January 2011). "Search for brown-dwarf companions of stars". Astronomy and Astrophysics. 525: A95. arXiv:1009.5991. Bibcode:2011A&A...525A..95S. doi:10.1051/0004-6361/201015427.