20 Boötis

20 Boötis is a single[7] star in the northern constellation of Boötes, located 183 light years away from the Sun. It is visible to the naked eye as a faint, orange-hued star with an apparent visual magnitude of 4.84.[2] The star has a relatively high proper motion, traversing the celestial sphere at the rate of 0.154 arc seconds per annum.[8] It is moving closer to the Earth with a heliocentric radial velocity of −8 km/s.[2]

20 Boötis
Observation data
Epoch J2000      Equinox J2000
Constellation Boötes
Right ascension 14h 19m 45.23505s[1]
Declination +16° 18′ 24.9955″[1]
Apparent magnitude (V) 4.84[2]
Characteristics
Spectral type K3 III[3]
B−V color index 1.228±0.001[2]
Astrometry
Radial velocity (Rv)−8.25±0.43[2] km/s
Proper motion (μ) RA: –141.521[1] mas/yr
Dec.: +60.274[1] mas/yr
Parallax (π)17.8379 ± 0.1894[1] mas
Distance183 ± 2 ly
(56.1 ± 0.6 pc)
Absolute magnitude (MV)1.01±0.09[4]
Details[4]
Mass1.14±0.19 M☉
Radius12.18+0.26
−0.36[1] R☉
Luminosity51.99±0.66[1] L☉
Surface gravity (log g)2.36±0.08 cgs
Temperature4,472 K
Metallicity [Fe/H]0.16 dex
Rotation848 days[5]
Rotational velocity (v sin i)1.0[5] km/s
Age5.21±2.28 Gyr
Other designations
20 Boo, NSV 6631, BD+16°2637, FK5 3135, GC 19334, GJ 3841, HD 125560, HIP 70027, HR 5370, SAO 100980[6]
Database references
SIMBADdata

This is an aging K-type giant star with a stellar classification of K3 III.[3] It is a red clump giant,[9] which indicates it is on the horizontal branch and is generating energy through helium fusion at its core. The star is around five billion years old with 1.1[4] times the mass of the Sun and has expanded to 12[1] times the Sun's radius. It is radiating 52[1] times the luminosity of the Sun from its swollen photosphere at an effective temperature of 4,472 K.[4]

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. 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. Roman, Nancy G. (July 1952), "The Spectra of the Bright Stars of Types F5-K5", Astrophysical Journal, 116: 122, Bibcode:1952ApJ...116..122R, doi:10.1086/145598.
  4. da Silva, L.; et al. (November 2006), "Basic physical parameters of a selected sample of evolved stars", Astronomy and Astrophysics, 458 (2): 609–623, arXiv:astro-ph/0608160, Bibcode:2006A&A...458..609D, doi:10.1051/0004-6361:20065105, S2CID 9341088.
  5. Setiawan, J.; et al. (July 2004), "Precise radial velocity measurements of G and K giants. Multiple systems and variability trend along the Red Giant Branch", Astronomy and Astrophysics, 421: 241–254, Bibcode:2004A&A...421..241S, doi:10.1051/0004-6361:20041042-1.
  6. "20 Boo". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved May 8, 2019.
  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. 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.
  9. 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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