11 Cephei
Observation data
Epoch J2000      Equinox J2000
Constellation Cepheus
Right ascension 21h 41m 55.31069s[1]
Declination +71° 18′ 41.2585″[1]
Apparent magnitude (V) 4.55[2]
Characteristics
Evolutionary stage horizontal branch[3]
Spectral type K0.5 III[4]
B−V color index 1.108±0.004[2]
Astrometry
Radial velocity (Rv)−38.36±0.19[2] km/s
Proper motion (μ) RA: +111.130[1] mas/yr
Dec.: +92.743[1] mas/yr
Parallax (π)17.6830 ± 0.1814 mas
Distance184 ± 2 ly
(56.6 ± 0.6 pc)
Absolute magnitude (MV)0.16[2]
Details[5]
Mass2.38±0.07 M☉
Radius10.93+0.27
−0.26 R☉
Luminosity94.9±8.8 L☉
Surface gravity (log g)2.41 cgs
Temperature5,446±113 K
Metallicity [Fe/H]0.17 dex
Rotational velocity (v sin i)1.0[6] km/s
Age670±60 Myr
Other designations
11 Cep, BD+70°1193, FK5 817, HD 206952, HIP 107119, HR 8317, SAO 10126[7]
Database references
SIMBADdata

11 Cephei is a single[8] star in the northern constellation of Cepheus,[7] located 184 light years away from the Sun.[1] It is visible to the naked eye as a faint, orange-hued star with an apparent visual magnitude of 4.55.[2] The star has a relatively high proper motion, traversing the celestial sphere at the rate of 0.153 arc seconds per annum.[9] It is moving closer to the Earth with a heliocentric radial velocity of −38 km/s.[2]

This is an aging giant star with a stellar classification of K0.5 III,[4] having exhausted the hydrogen at its core and expanded. It is a red clump giant, which means it is currently on the horizontal branch and is generating energy through helium fusion at the core.[3] 11 Cephei is 670 million years old with 2.4 times the mass of the Sun and 11 times the Sun's radius. It is radiating around 95 times the luminosity of the Sun from its swollen photosphere at an effective temperature of 5,446 K.[5]

References

  1. ^ a b c d e 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. ^ a b c d e f 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.
  3. ^ a b 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.
  4. ^ a b 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, ISSN 0067-0049.
  5. ^ a b Baines, Ellyn K.; et al. (2018), "Fundamental Parameters of 87 Stars from the Navy Precision Optical Interferometer", The Astronomical Journal, 155 (1), 30, arXiv:1712.08109, Bibcode:2018AJ....155...30B, doi:10.3847/1538-3881/aa9d8b, S2CID 119427037.
  6. ^ De Medeiros, J. R.; et al. (November 2000), "Rotation and lithium in single giant stars", Astronomy and Astrophysics, 363: 239–243, arXiv:astro-ph/0010273, Bibcode:2000A&A...363..239D.
  7. ^ a b "11 Cep". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved April 28, 2019.
  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, S2CID 14878976.
  9. ^ 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.
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