15 Cygni

15 Cygni is a single[7] star in the northern constellation Cygnus. With an apparent visual magnitude of 4.90,[2] it is a faint star but visible to the naked eye. The distance to 15 Cygni can be estimated from its annual parallax shift of 11.0 mas,[1] which yields a separation of some 296 light years. It is moving closer to the Sun with a heliocentric radial velocity of −23.6 km/s.[4]

15 Cygni
Observation data
Epoch J2000      Equinox J2000
Constellation Cygnus
Right ascension 19h 44m 16.60522s[1]
Declination +37° 21′ 15.6771″[1]
Apparent magnitude (V) 4.90[2]
Characteristics
Spectral type G8 III[2]
B−V color index 0.931[3]
Astrometry
Radial velocity (Rv)−23.62±0.21[4] km/s
Proper motion (μ) RA: +72.660[1] mas/yr
Dec.: +35.708[1] mas/yr
Parallax (π)11.0063 ± 0.1188[1] mas
Distance296 ± 3 ly
(90.9 ± 1.0 pc)
Absolute magnitude (MV)0.19[5]
Details
Mass2.30[3] M☉
Radius12[4] R☉
Luminosity93.3[3] L☉
Surface gravity (log g)2.8[4] cgs
Temperature4,920±61[3] K
Metallicity [Fe/H]−0.14[4] dex
Rotational velocity (v sin i)2.8[4] km/s
Age1.50[3] Gyr
Other designations
15 Cyg, BD+37°3586, FK5 740, HD 186675, HIP 97118, HR 7517, SAO 68778[6]
Database references
SIMBADdata

This is an aging giant star with a stellar classification of G8 III,[2] having consumed the hydrogen at its core and evolved off the main sequence. It is a red clump giant,[8] which means it is generating energy via helium fusion at its core. The star is 1.50 billion years old with 2.3 times the mass of the Sun,[3] and has expanded to 12 times the Sun's radius.[4] It is radiating 93 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,920 K.[3]

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. Keenan, Philip C.; McNeil, Raymond C. (1989), "The Perkins catalog of revised MK types for the cooler stars", Astrophysical Journal Supplement Series, 71: 245, Bibcode:1989ApJS...71..245K, doi:10.1086/191373.
  3. Luck, R. Earle (2015), "Abundances in the Local Region. I. G and K Giants", The Astronomical Journal, 150 (3): 88, arXiv:1507.01466, Bibcode:2015AJ....150...88L, doi:10.1088/0004-6256/150/3/88, S2CID 118505114.
  4. Massarotti, Alessandro; et al. (January 2008), "Rotational and Radial Velocities for a Sample of 761 Hipparcos Giants and the Role of Binarity", The Astronomical Journal, 135 (1): 209–231, Bibcode:2008AJ....135..209M, doi:10.1088/0004-6256/135/1/209
  5. Takeda, Yoichi; et al. (February 2005), "Stellar Parameters and Photospheric Abundances of Late-G Giants: Properties of the Targets of the Okayama Planet Search Program", Publications of the Astronomical Society of Japan, 57 (1): 109–125, Bibcode:2005PASJ...57..109T, doi:10.1093/pasj/57.1.109.
  6. "15 Cyg". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-01-09.
  7. 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, S2CID 14878976.
  8. Alves, David R. (August 2000), "K-Band Calibration of the Red Clump Luminosity", The Astrophysical Journal, 539 (2): 732–741, arXiv:astro-ph/0003329, Bibcode:2000ApJ...539..732A, doi:10.1086/309278, S2CID 16673121.
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