Astronomy:6 Draconis
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| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Draco |
| Right ascension | 12h 34m 44.01929s[1] |
| Declination | +70° 01′ 18.4053″[1] |
| Apparent magnitude (V) | 4.95[2] |
| Characteristics | |
| Evolutionary stage | red giant branch[1] |
| Spectral type | K2.5 III Fe-2[3] + A8–9 V[4] |
| B−V color index | 1.312±0.003[2] |
| Astrometry | |
| Radial velocity (Rv) | 3.38±0.30[2] km/s |
| Proper motion (μ) | RA: −32.393[1] mas/yr Dec.: −4.449[1] mas/yr |
| Parallax (π) | 6.6159 ± 0.4238[1] mas |
| Distance | 490 ± 30 ly (151 ± 10 pc) |
| Absolute magnitude (MV) | −1.35[2] |
| Orbit[4] | |
| Period (P) | 561.7±0.3 d |
| Eccentricity (e) | 0.262±0.017 |
| Periastron epoch (T) | 45525±5 MJD |
| Argument of periastron (ω) (secondary) | 9±4° |
| Semi-amplitude (K1) (primary) | 6.90±0.12 km/s |
| Details | |
| Mass | 1.28[5] M☉ |
| Radius | 33[6] R☉ |
| Luminosity | 316[6] L☉ |
| Surface gravity (log g) | 1.43[7] cgs |
| Temperature | 4,134[7] K |
| Metallicity [Fe/H] | −0.22[5] dex |
| Rotational velocity (v sin i) | 1.7[8] km/s |
| Age | 2.2[7] Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
6 Draconis is a single-lined spectroscopic binary[4] star system in the northern constellation of Draco, located about 430 light years away from the Sun. It is visible to the naked eye as an orange-hued star with an apparent visual magnitude of 4.95.[2] The system is moving further from the Earth with a heliocentric radial velocity of 3 km/s.[2]
The variable radial velocity of this star system was announced by W. W. Campbell in 1922. Griffin et al. (1990) found an orbital period of 1.5 yr and an eccentricity of 0.26. The primary has an "a sin i" value of 51.4 Gm (0.34 astronomical unit|AU), where a is the semimajor axis and i is the (unknown) orbital inclination. This value provides a lower bound on the actual semimajor axis, which is one half of the longest dimension of their elliptical orbit.[4]
The visible component is an evolved giant star with a stellar classification of K2.5 III Fe-2,[3] where the suffix notation indicates a pronounced underabundance of iron in the spectrum. The measured angular diameter of this star, after correction for limb darkening, is 2.54±0.04 mas.[10] At its estimated distance, this yields a physical size of about 33 times the radius of the Sun.[6] It is radiating 316 times the Sun's luminosity[6] from its enlarged photosphere at an effective temperature of 4,134 K.[7] The companion is most likely an A-type main-sequence star with a class of A8–9 V.[4]
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940 Gaia DR3 record for this source at VizieR.
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters 38 (5): 331, doi:10.1134/S1063773712050015, Bibcode: 2012AstL...38..331A.
- ↑ 3.0 3.1 Keenan, Philip C.; McNeil, Raymond C. (1989), "The Perkins catalog of revised MK types for the cooler stars", Astrophysical Journal Supplement Series 71: 245, doi:10.1086/191373, Bibcode: 1989ApJS...71..245K.
- ↑ 4.0 4.1 4.2 4.3 4.4 Griffin, R. F. et al. (June 1990), "The spectroscopic orbit of 6 Draconis", Journal of Astrophysics and Astronomy 11 (2): 255, doi:10.1007/BF02715020, Bibcode: 1990JApA...11..255G
- ↑ 5.0 5.1 Khalatyan, A.; Anders, F.; Chiappini, C.; Queiroz, A. B. A.; Nepal, S.; Dal Ponte, M.; Jordi, C.; Guiglion, G. et al. (2024). "Transferring spectroscopic stellar labels to 217 million Gaia DR3 XP stars with SHBoost". Astronomy & Astrophysics 691: A98. doi:10.1051/0004-6361/202451427. Bibcode: 2024A&A...691A..98K.
- ↑ 6.0 6.1 6.2 6.3 Fetherolf, Tara; Pepper, Joshua; Simpson, Emilie; Kane, Stephen R.; Močnik, Teo; English, John Edward; Antoci, Victoria; Huber, Daniel et al. (2023), "Variability Catalog of Stars Observed during the TESS Prime Mission", The Astrophysical Journal Supplement Series 268 (1): 4, doi:10.3847/1538-4365/acdee5, Bibcode: 2023ApJS..268....4F.
- ↑ 7.0 7.1 7.2 7.3 Kordopatis, G. et al. (2023). "Stellar ages, masses, extinctions, and orbital parameters based on spectroscopic parameters of Gaia DR3". Astronomy and Astrophysics 669: A104. doi:10.1051/0004-6361/202244283. Bibcode: 2023A&A...669A.104K.
- ↑ De Medeiros, J. R. et al. (October 2002), "The Rotation of Binary Systems with Evolved Components", The Astrophysical Journal 578 (2): 943–950, doi:10.1086/342613, Bibcode: 2002ApJ...578..943D.
- ↑ "6 Dra". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=6+Dra.
- ↑ Richichi, A.; Percheron, I.; Khristoforova, M. (February 2005), "CHARM2: An updated Catalog of High Angular Resolution Measurements", Astronomy and Astrophysics 431 (2): 773–777, doi:10.1051/0004-6361:20042039, Bibcode: 2005A&A...431..773R.
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