39 Draconis is a wide binary star system in the northern circumpolar constellation of Draco. It has the Bayer designation b Draconis, while 39 Draconis is the Flamsteed designation. This system is visible to the naked eye as a dim, white-hued point of light with an apparent visual magnitude of 5.0.[2] Parallax measurements made by the Hipparcos spacecraft put it at a distance of 184 light-years, or 56 parsecs away from the Sun.[1] The system is moving closer to the Earth with a heliocentric radial velocity of -24.5 km/s.[6]
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Draco |
| Right ascension | 18h 23m 54.60641s[1] |
| Declination | 58° 48′ 02.6446″[1] |
| Apparent magnitude (V) | 5.034[2] (5.06 8.07)[3] |
| Characteristics | |
| Spectral type | A1V F5V[4] |
| U−B color index | 0.06[5] |
| B−V color index | 0.10[5] |
| Astrometry | |
| Radial velocity (Rv) | −24.53±0.23[6] km/s |
| Proper motion (μ) | RA: −37.82[1] mas/yr Dec.: 61.60[1] mas/yr |
| Parallax (π) | 17.71 ± 0.35 mas[1] |
| Distance | 184 ± 4 ly (56 ± 1 pc) |
| Absolute magnitude (MV) | 1.31 / 4.32[7] |
| Orbit[3] | |
| Period (P) | 3962.50 ± 209.26 yr |
| Semi-major axis (a) | 6.621 ± 0.325″ |
| Eccentricity (e) | 0.553 ± 0.005 |
| Inclination (i) | 107.7 ± 0.12° |
| Longitude of the node (Ω) | 179.9 ± 0.10° |
| Periastron epoch (T) | 5671.40 ± 12.08 |
| Argument of periastron (ω) (secondary) | 128.0 ± 2.18° |
| Details | |
| 39 Dra A | |
| Mass | 2.12[7] M☉ |
| Radius | 2.3[8] R☉ |
| Surface gravity (log g) | 4.05 ± 0.07[8] cgs |
| Temperature | 8710[8] K |
| 39 Dra B | |
| Mass | 1.18[7] M☉ |
| Other designations | |
| Database references | |
| SIMBAD | 39 Dra |
| 39 Dra A | |
| 39 Dra B | |
The two components of 39 Draconis have an angular separation of 6.621″ and take almost 4,000 years to orbit each other.[3] The primary star is an early A-type main-sequence star, having 2.12 times the mass of the Sun with a visual magnitude of 5.06[3] The secondary is a magnitude 8.07[3] F-type main-sequence star, and has 1.18 times the mass of the Sun.[7]
The 8th-magnitude star HD 238865 is listed in double star catalogues as component C.[9] It is separated from the other two stars by 90″ and lies at about the same distance.[10] It is itself a spectroscopic binary with an F8 primary and a red dwarf secondary orbiting every 2.7 days.[11][12]
References
edit- ^ a b c d e f van Leeuwen, F.; et al. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. S2CID 18759600.
- ^ a b c "* b Dra". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 21 June 2017.
- ^ a b c d e "Sixth Catalog of Orbits of Visual Binary Stars". United States Naval Observatory. Archived from the original on 2017-08-01. Retrieved 2017-06-22.
- ^ Lutz, T. E.; Lutz, J. H. (1977). "Spectral classification and UBV photometry of bright visual double stars". The Astronomical Journal. 82: 431. Bibcode:1977AJ.....82..431L. doi:10.1086/112066.
- ^ a b Mermilliod, J.-C. (1986). "Compilation of Eggen's UBV data, transformed to UBV (unpublished)". Catalogue of Eggen's UBV Data. Bibcode:1986EgUBV........0M.
- ^ a b Pourbaix, D.; et al. (2004). "SB9: The ninth catalogue of spectroscopic binary orbits". Astronomy and Astrophysics. 424 (2): 727–732. arXiv:astro-ph/0406573. Bibcode:2004A&A...424..727P. doi:10.1051/0004-6361:20041213. S2CID 119387088.
- ^ a b c d Novakovic, B.; Todorovic, N. (2006). "Orbits of four double stars". Serbian Astronomical Journal. 172 (172): 21. Bibcode:2006SerAJ.172...21N. doi:10.2298/SAJ0672021N. S2CID 55352155.
- ^ a b c Allende Prieto, C.; Lambert, D. L. (1999). "Fundamental parameters of nearby stars from the comparison with evolutionary calculations: masses, radii and effective temperatures". Astronomy and Astrophysics. 352: 555–562. arXiv:astro-ph/9911002. Bibcode:1999A&A...352..555A.
- ^ Mason, B. D.; et al. (2014). "The Washington Visual Double Star Catalog". The Astronomical Journal. 122 (6): 3466–3471. Bibcode:2001AJ....122.3466M. doi:10.1086/323920.
- ^ Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
- ^ De Rosa, R. J.; Patience, J.; Wilson, P. A.; Schneider, A.; Wiktorowicz, S. J.; Vigan, A.; Marois, C.; Song, I.; MacIntosh, B.; Graham, J. R.; Doyon, R.; Bessell, M. S.; Thomas, S.; Lai, O. (2014). "The VAST Survey - III. The multiplicity of A-type stars within 75 pc". Monthly Notices of the Royal Astronomical Society. 437 (2): 1216. arXiv:1311.7141. Bibcode:2014MNRAS.437.1216D. doi:10.1093/mnras/stt1932. S2CID 88503488.
- ^ Tokovinin, A. A.; Smekhov, M. G. (1995). "Spectroscopic components in multiple systems: ADS 11336C". Astronomy Letters. 21 (2): 247. Bibcode:1995AstL...21..247T.