HD 200661 (HR 8067) is a solitary star in the equatorial constellation Equuleus. It has an apparent magnitude of 6.41, placing it near the max naked eye visibility. The star is situated at a distance of 430 light years[1] but is approaching with a heliocentric radial velocity of −12.1 km/s.[6]

HD 200661
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Equuleus
Right ascension 21h 04m 41.6405s[1]
Declination +02° 56′ 32.1874″[1]
Apparent magnitude (V) 6.41±0.01[2]
Characteristics
Evolutionary stage horizontal branch[3]
Spectral type K0 III[4]
U−B color index +0.89[5]
B−V color index +1.06[5]
Astrometry
Radial velocity (Rv)−12.1 ± 0.2[6] km/s
Proper motion (μ) RA: +13.336[1] mas/yr
Dec.: +5.800[1] mas/yr
Parallax (π)7.5933 ± 0.0353 mas[1]
Distance430 ± 2 ly
(131.7 ± 0.6 pc)
Absolute magnitude (MV)+0.53[7]
Details
Mass1.74[8] M
Radius10.62[9] R
Luminosity51.3[10] L
Surface gravity (log g)2.1[11] cgs
Temperature4,740[10] K
Metallicity [Fe/H]−0.1[8] dex
Other designations
7 G. Equueli, AG+02° 2688, BD+02°4297, GC 29434, HD 200661, HIP 104041, HR 8067, SAO 126519[12]
Database references
SIMBADdata

HD 200661 has a stellar classification of K0 III,[4] indicating that the object is an early K-type giant star that is on the horizontal branch.[3] It has an angular diameter of 0.75±0.05 mas, which yields a diameter 10.62[9] times that of the Sun at its estimated distance. At present HD 200661 has 1.74 times the Sun’s mass,[8] and shines at 51.3 times the luminosity of the Sun[10] from its enlarged photosphere at an effective temperature of 4,740 K,[10] giving it a yellow-orange glow.

References

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  1. ^ a b c d e f Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
  2. ^ Høg, E.; Fabricius, C.; Makarov, V. V.; Urban, S.; Corbin, T.; Wycoff, G.; Bastian, U.; Schwekendiek, P.; Wicenec, A. (1 March 2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics. 355: L27–L30. Bibcode:2000A&A...355L..27H. ISSN 0004-6361.
  3. ^ a b Gontcharov, G. A. (November 2008). "Red giant clump in the Tycho-2 catalogue". Astronomy Letters. 34 (11): 785–796. arXiv:1607.00619. Bibcode:2008AstL...34..785G. doi:10.1134/S1063773708110078. ISSN 0004-6299. S2CID 73524157.
  4. ^ a b Houk, N.; Swift, C. (1999). "Michigan catalogue of two-dimensional spectral types for the HD Stars, Vol. 5". Michigan Spectral Survey. 05: 0. Bibcode:1999MSS...C05....0H.
  5. ^ a b Cousins, A. W. J. (1971). "Photometric standard stars". Royal Observatory Annals. 7. Bibcode:1971ROAn....7.....C.
  6. ^ a b Famaey, B.; Jorissen, A.; Luri, X.; Mayor, M.; Udry, S.; Dejonghe, H.; Turon, C. (2005). "Local kinematics of K and M giants from CORAVEL/Hipparcos/Tycho-2 data. Revisiting the concept of superclusters". Astronomy and Astrophysics. 430: 165. arXiv:astro-ph/0409579. Bibcode:2005A&A...430..165F. doi:10.1051/0004-6361:20041272. S2CID 17804304.
  7. ^ Anderson, E.; Francis, Ch. (1 May 2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331–346. arXiv:1108.4971. Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015. ISSN 1063-7737. S2CID 119257644.
  8. ^ a b c Anders, F.; et al. (1 August 2019). "Photo-astrometric distances, extinctions, and astrophysical parameters for Gaia DR2 stars brighter than G = 18". Astronomy and Astrophysics. 628: A94. arXiv:1904.11302. Bibcode:2019A&A...628A..94A. doi:10.1051/0004-6361/201935765. ISSN 0004-6361. S2CID 131780028.
  9. ^ a b Lang, Kenneth R. (2006). Astrophysical formulae. Astronomy and astrophysics library. Vol. 1 (3 ed.). Birkhäuser. ISBN 3-540-29692-1.. The radius (R*) is given by:
     
  10. ^ a b c d McDonald, I.; Zijlstra, A. A.; Watson, R. A. (2017). "Fundamental parameters and infrared excesses of Tycho-Gaia stars". Monthly Notices of the Royal Astronomical Society. 471 (1): 770. arXiv:1706.02208. Bibcode:2017MNRAS.471..770M. doi:10.1093/mnras/stx1433.
  11. ^ Lafrasse, Sylvain; Mella, Guillaume; Bonneau, Daniel; Duvert, Gilles; Delfosse, Xavier; Chesneau, Olivier; Chelli, Alain (16 July 2010). "Building the 'JMMC Stellar Diameters Catalog' using SearchCal". Optical and Infrared Interferometry II. Vol. 7734. pp. 77344E. arXiv:1009.0137. Bibcode:2010SPIE.7734E..4EL. doi:10.1117/12.857024. S2CID 32097037.
  12. ^ "HR 8067". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 11 September 2021.