50 Draconis

Last updated
50 Draconis
Observation data
Epoch J2000       Equinox J2000
Constellation Draco [1]
Right ascension 18h 46m 22.24188s [2]
Declination +75° 26 02.2400 [2]
Apparent magnitude  (V)5.369±0.001 [3]
(5.997 + 6.238) [4]
Characteristics
Evolutionary stage Main sequence [4]
Spectral type A2Vp [1]
Variable type Rotating ellipsoidal variable [4]
Astrometry
Radial velocity (Rv)−6.53±0.09 [4] km/s
Proper motion (μ)RA: −17.061 mas/yr [2]
Dec.: +70.391 mas/yr [2]
Parallax (π)11.4150±0.1058  mas [2]
Distance 286 ± 3  ly
(87.6 ± 0.8  pc)
Absolute magnitude  (MV)+0.70 [1]
Orbit [4]
Period (P)4.117719(2) days
Semi-major axis (a)13.184±0.026  R
Eccentricity (e)0.0021±0.0003
Inclination (i)49.9±0.8°
Argument of periastron (ω)
(secondary)
94.85±0.02°
Semi-amplitude (K1)
(primary)
78.93±0.02 km/s
Semi-amplitude (K2)
(secondary)
82.96±0.20 km/s
Details [4]
50 Dra A
Mass 2.08±0.08  M
Radius 2.06±0.09  R
Surface gravity (log g)4.13±0.05  cgs
Temperature 9,800±100  K
Metallicity [Fe/H]+0.21±0.09  dex
Rotation 4.117719(2) days
Rotational velocity (v sin i)19±1 km/s
50 Dra B
Mass 1.97±0.08  M
Radius 1.99±0.09  R
Surface gravity (log g)4.13±0.05  cgs
Temperature 9,200±200  K
Metallicity [Fe/H]+0.08±0.10  dex
Rotation 4.117719(2) days
Rotational velocity (v sin i)19±1 km/s
Other designations
BD+75°682, HD 175286, HIP 92112, HR 7124, TYC 4583-2839-1 [5]
Database references
SIMBAD data

50 Draconis is a binary star in the constellation Draco. At an apparent magnitude of +5.369, it is faintly visible to the naked eye in locations far from light pollution. Parallax measurements give a distance of 286 light-years (88 parsecs ).

Characteristics

50 Draconis was first discovered to be a binary in 1914 at the American Astronomical Society. [6] A spectroscopic binary, the existence of a companion was inferred from periodic variations in the spectral lines, corresponding to the orbital motion of the stars. [4]

The system has a very tight orbit, with an orbital period of just 4.11 days and an orbital separation of 13.184 solar radii (9,172,000 km) at a low eccentricity of 0.002. The orbit is inclined at 50 degrees from Earth and thus the system is not eclipsing. The components are so close to each other that their shapes are distorted by gravity, and during the orbit the surfaces visible from Earth, and hence the luminosities, vary, making the system a rotating ellipsoidal variable. The stars are tidally locked, with rotation periods synchronized with the orbital period. [4]

Relative to the Sun, the stars are overabundant in iron peak and rare-earth elements, but underabundant in scandium, classifying them as Am stars. The components are similar to each other, with around twice the mass and radius of the Sun, and effective temperatures of 9,800 and 9,200  K for the primary and secondary respectively, temperatures at the upper range for Am stars. [4]

References

  1. 1 2 3 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.
  2. 1 2 3 4 5 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.
  3. Paunzen, E. (2015-08-01). "A new catalogue of Strömgren-Crawford uvbyβ photometry". Astronomy and Astrophysics. 580: A23. arXiv: 1506.04568 . Bibcode:2015A&A...580A..23P. doi:10.1051/0004-6361/201526413. ISSN   0004-6361.
  4. 1 2 3 4 5 6 7 8 9 Skarka, M.; Lipták, J.; Niemczura, E.; Mikulášek, Z.; Cabezas, M.; Vítková, M.; Karjalainen, R.; Kabáth, P. (June 2025). "50 Dra: Am-type twins with additional variability in a non-eclipsing system". Astronomy & Astrophysics. 698: A48. arXiv: 2504.05854 . Bibcode:2025A&A...698A..48S. doi:10.1051/0004-6361/202452341. ISSN   0004-6361.
  5. "50 Dra". SIMBAD . Centre de données astronomiques de Strasbourg.
  6. Harper, W. E. (April 1915). "The Orbits of the Spectroscopic Components of 50 Draconis". Journal of the Royal Astronomical Society of Canada. 9: 165. Bibcode:1915JRASC...9..165H. ISSN   0035-872X.