68 Draconis

From Wikipedia, the free encyclopedia
Jump to: navigation, search
68 Draconis
Observation data
Epoch J2000      Equinox J2000
Constellation Draco
Right ascension 20h 11m 34.91482s[1]
Declination +62° 04′ 42.7542″[1]
Apparent magnitude (V) 5.69[2]
Spectral type F5 V[2]
B−V color index 0.48[3]
Radial velocity (Rv) –14.6[4] km/s
Proper motion (μ) RA: +137.01[1] mas/yr
Dec.: +80.45[1] mas/yr
Parallax (π) 20.68 ± 0.42[1] mas
Distance 158 ± 3 ly
(48.4 ± 1.0 pc)
Absolute magnitude (MV) 2.33[5]
Surface gravity (log g) 3.95[3] cgs
Temperature 6,137[3] K
Metallicity [Fe/H] 0.20[5] dex
Rotational velocity (v sin i) 15.1[3] km/s
Age 1.7[5] Gyr
Other designations
68 Dra, BD+61° 1983, HD 192455, HIP 99500, HR 7727, SAO 18751.[6]
Database references

68 Draconis is the Flamsteed designation for a star in the northern constellation of Draco. It has an apparent visual magnitude of 5.69,[2] so, according to the Bortle scale, it is faintly visible to the naked eye from suburban skies at night. Measurements made with the Hipparcos spacecraft show an annual parallax shift of 0.02068″,[1] which is equivalent to a distance of around 158 ly (48 pc) from the Sun.

The stellar classification of 68 Draconis is F5 V,[2] indicating that it is a main sequence star that is fusing hydrogen into helium at its core to generate energy. The star appears to be over-luminous for a member of its class, being 0.73 magnitudes brighter than expected. This may indicate that this is a binary system with an unresolved secondary component.[2] It is less than half as old as the Sun, with an estimated age of 1.7 billion years.[5] The effective temperature of the stellar atmosphere is 6,137 K,[3] giving it the yellow-white hue of an F-type star.[7]


  1. ^ a b c d e f van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752Freely accessible, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357. 
  2. ^ a b c d e Griffin, R. F.; Suchkov, A. A. (July 2003), "The Nature of Overluminous F Stars Observed in a Radial-Velocity Survey", The Astrophysical Journal Supplement Series, 147 (1): 103–144, Bibcode:2003ApJS..147..103G, doi:10.1086/367855. 
  3. ^ a b c d e Schröder, C.; Reiners, A.; Schmitt, J. H. M. M. (January 2009), "Ca II HK emission in rapidly rotating stars. Evidence for an onset of the solar-type dynamo", Astronomy and Astrophysics, 493 (3): 1099–1107, Bibcode:2009A&A...493.1099S, doi:10.1051/0004-6361:200810377. 
  4. ^ Nordström, B.; et al. (May 2004), "The Geneva-Copenhagen survey of the Solar neighbourhood. Ages, metallicities, and kinematic properties of ˜14,000 F and G dwarfs", Astronomy and Astrophysics, 418: 989–1019, arXiv:astro-ph/0405198Freely accessible, Bibcode:2004A&A...418..989N, doi:10.1051/0004-6361:20035959. 
  5. ^ a b c d Holmberg, J.; et al. (July 2009), "The Geneva-Copenhagen survey of the solar neighbourhood. III. Improved distances, ages, and kinematics", Astronomy and Astrophysics, 501 (3): 941–947, arXiv:0811.3982Freely accessible, Bibcode:2009A&A...501..941H, doi:10.1051/0004-6361/200811191. 
  6. ^ "68 Dra -- Star in double system", SIMBAD Astronomical Database, Centre de Données astronomiques de Strasbourg, retrieved 2013-11-06. 
  7. ^ "The Colour of Stars", Australia Telescope, Outreach and Education, Commonwealth Scientific and Industrial Research Organisation, December 21, 2004, archived from the original on March 10, 2012, retrieved 2012-01-16. 

Coordinates: Sky map 20h 11m 34.91s, +62° 04′ 42.75″