Summary
68 Draconis is the Flamsteed designation for a star in the northern circumpolar 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 Gaia spacecraft show an annual parallax shift of 0.0209232″,[1] which is equivalent to a distance of around 156 ly (48 pc) from the Sun. It is moving closer to the Earth with a heliocentric radial velocity of –14.6 km/s.[4] The star has a relatively high proper motion, traversing the celestial sphere at a rate of 0.150″ per year.[9]
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Draco |
| Right ascension | 20h 11m 34.872s[1] |
| Declination | +62° 04′ 42.77″[1] |
| Apparent magnitude (V) | 5.69[2] |
| Characteristics | |
| Spectral type | F5 V[2] |
| B−V color index | 0.48[3] |
| Astrometry | |
| Radial velocity (Rv) | –14.6[4] km/s |
| Proper motion (μ) | RA: +142.267 mas/yr[1] Dec.: +72.842 mas/yr[1] |
| Parallax (π) | 20.9232 ± 0.065 mas[1] |
| Distance | 155.9 ± 0.5 ly (47.8 ± 0.1 pc) |
| Absolute magnitude (MV) | 2.33[5] |
| Details | |
| Mass | 1.15[6] M☉ |
| Luminosity | 10.73[7] L☉ |
| 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 | |
| Database references | |
| SIMBAD | data |
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 has 15%[6] more mass than the Sun but is less than half as old, with an estimated age of 1.7 billion years.[5] The star is radiating 11[7] times the Sun's luminosity from its photosphere at an effective temperature of 6,137 K,[3] giving it the yellow-white hue of an F-type star.[10]
References edit
- ^ a b c d e Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
- ^ 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.
- ^ a b c d e Schröder, C.; Reiners, Ansgar; Schmitt, Jürgen H. M. M. (January 2009), "Ca II HK emission in rapidly rotating stars. Evidence for an onset of the solar-type dynamo" (PDF), Astronomy and Astrophysics, 493 (3): 1099–1107, Bibcode:2009A&A...493.1099S, doi:10.1051/0004-6361:200810377[permanent dead link]
- ^ a b 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/0405198, Bibcode:2004A&A...418..989N, doi:10.1051/0004-6361:20035959, S2CID 11027621.
- ^ 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:0811.3982, Bibcode:2009A&A...501..941H, doi:10.1051/0004-6361/200811191, S2CID 118577511.
- ^ a b David, Trevor J.; Hillenbrand, Lynne A. (2015), "The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets", The Astrophysical Journal, 804 (2): 146, arXiv:1501.03154, Bibcode:2015ApJ...804..146D, doi:10.1088/0004-637X/804/2/146, S2CID 33401607.
- ^ a b 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, S2CID 119257644.
- ^ "68 Dra". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2013-11-06.
- ^ Lépine, Sébastien; Shara, Michael M. (March 2005), "A Catalog of Northern Stars with Annual Proper Motions Larger than 0.15" (LSPM-NORTH Catalog)", The Astronomical Journal, 129 (3): 1483–1522, arXiv:astro-ph/0412070, Bibcode:2005AJ....129.1483L, doi:10.1086/427854, S2CID 2603568.
- ^ "The Colour of Stars", Australia Telescope, Outreach and Education, Commonwealth Scientific and Industrial Research Organisation, December 21, 2004, archived from the original on March 18, 2012, retrieved 2012-01-16.