39 Draconis

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39 Draconis
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)4,0000 ± 2000 yr
Semi-major axis (a)6.6 ± 0.3″
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 ± 2.2°
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
b Dra, 39 Dra, BD+58°1809, HD 170073, HIP 90156, HR 6923, SAO 30949 [2]
Database references
SIMBAD 39 Dra
39 Dra A
39 Dra B

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]

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

  1. 1 2 3 4 5 6 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.
  2. 1 2 3 "* b Dra". SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved 21 June 2017.
  3. 1 2 3 4 5 "Sixth Catalog of Orbits of Visual Binary Stars". United States Naval Observatory. Archived from the original on 2017-08-01. Retrieved 2017-06-22.
  4. ↑ 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 .
  5. 1 2 Mermilliod, J.-C. (1986). "Compilation of Eggen's UBV data, transformed to UBV (unpublished)". Catalogue of Eggen's UBV Data. Bibcode:1986EgUBV........0M.
  6. 1 2 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.
  7. 1 2 3 4 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.
  8. 1 2 3 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.
  9. ↑ 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 .
  10. ↑ 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 .
  11. ↑ 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.
  12. ↑ Tokovinin, A. A.; Smekhov, M. G. (1995). "Spectroscopic components in multiple systems: ADS 11336C". Astronomy Letters. 21 (2): 247. Bibcode:1995AstL...21..247T.
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