26 Cygni

26 Cygni is a single[8] star in the northern constellation of Cygnus. It has the Bayer designation e Cygni, while 26 Cygni is the Flamsteed designation. This star is visible to the naked eye as a faint, yellow-hued point of light with an apparent visual magnitude of 5.12.[2] It is located around 451 light-years (138 pc) distant from the Sun,[1] based on parallax measurements. The radial velocity is close to negligible, being measured at −0.3 km/s.[1]

26 Cygni
Observation data
Epoch J2000      Equinox J2000
Constellation Cygnus
Right ascension  20h 01m 21.56485s[1]
Declination +50° 06′ 16.8912″[1]
Apparent magnitude (V) 5.12[2]
Characteristics
Evolutionary stage giant
Spectral type G8 III[3]
B−V color index 1.122[4]
Astrometry
Radial velocity (Rv)−0.25±0.16[1] km/s
Proper motion (μ) RA: +15.520[1] mas/yr
Dec.: +5.805[1] mas/yr
Parallax (π)7.2271 ± 0.0853[1] mas
Distance451 ± 5 ly
(138 ± 2 pc)
Absolute magnitude (MV)−0.56[5]
Details
Mass2.44[6] M☉
Radius22.27[6] R☉
Luminosity204.8[6] L☉
Surface gravity (log g)2.50[4] cgs
Temperature4,700[4] K
Metallicity [Fe/H]−0.09±0.04[5] dex
Rotational velocity (v sin i)3.63[4] km/s
Other designations
e Cyg, 26 Cyg, BD+49°3158, HD 190147, HIP 98571, HR 7660, SAO 49098, ADS 13278, WDS J20014+5006, 2MASS J20012157+5006167[7]
Database references
SIMBADdata

This object is an evolved giant star with a stellar classification of G8 III;[3] a star that has used up its core hydrogen and left the main sequence. It is most likely (88% chance) on the horizontal branch, in which case stellar modelling yields an estimated 2.44 times the mass of the Sun and 22 times the Sun's radius.[6] It is radiating 205[6] times the luminosity of the Sun from its enlarged photosphere at an effective temperature of 4,700 K.[4]

There is a magnitude 8.94 visual companion at an angular separation of 41.6″ along a position angle of 150°, as of 2014.[9]

References
  1. 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.
  2. Fernie, J. D. (1983). "New UBVRI photometry for 900 supergiants". Astrophysical Journal Supplement Series. 52: 7. Bibcode:1983ApJS...52....7F. doi:10.1086/190856.
  3. Abt, Helmut A. (2008). "Visual Multiples. IX. MK Spectral Types". The Astrophysical Journal Supplement Series. 176: 216–217. Bibcode:2008ApJS..176..216A. doi:10.1086/525529.
  4. Hekker, S.; Meléndez, J. (2007). "Precise radial velocities of giant stars. III. Spectroscopic stellar parameters". Astronomy and Astrophysics. 475 (3): 1003. arXiv:0709.1145. Bibcode:2007A&A...475.1003H. doi:10.1051/0004-6361:20078233.
  5. 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.
  6. Stock, Stephan; et al. (August 2018). "Precise radial velocities of giant stars. X. Bayesian stellar parameters and evolutionary stages for 372 giant stars from the Lick planet search". Astronomy & Astrophysics. 616: 15. arXiv:1805.04094. Bibcode:2018A&A...616A..33S. doi:10.1051/0004-6361/201833111. A33.
  7. "26 Cyg". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-01-11.
  8. Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869–879, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x.
  9. Mason, B. D.; et al. (2014), The Washington Visual Double Star Catalog, Bibcode:2001AJ....122.3466M, doi:10.1086/323920, retrieved 2015-07-22
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