Astronomy:HD 200779

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Short description: High proper motion star; Equuleus
HD 200779
Observation data
Epoch J2000.0   Equinox (celestial coordinates)
Constellation Equuleus
Right ascension  21h 05m 19.74605s[1]
Declination +07° 04′ 09.4729″[1]
Apparent magnitude (V) 8.27[2]
Characteristics
Spectral type K6 V[3]
U−B color index +1.12[4]
B−V color index +1.21[4]
R−I color index +0.61[2]
Astrometry
Radial velocity (Rv)−66.94±0.18[5] km/s
Proper motion (μ) RA: +78.562[1] mas/yr
Dec.: −563.909[1] mas/yr
Parallax (π)66.4626 ± 0.0225[1] mas
Distance49.07 ± 0.02 ly
(15.046 ± 0.005 pc)
Absolute magnitude (MV)+7.38[6]
Details
Mass0.68±0.01[7] M☉
Radius0.689+0.077−0.050[8] R☉
Luminosity0.18[9] L☉
Surface gravity (log g)4.67±0.02[7] cgs
Temperature4,406±73[10] K
Metallicity [Fe/H]+0.05±0.06[7] dex
Rotational velocity (v sin i)5.1±1.2[5] km/s
Age6.33[11] Gyr
Other designations
BD+06°4741, GC 29447, GJ 818, HD 200779, HIP 104092, SAO 126533, CCDM J21054+0704A, WDS J21053+0704A, LFT 160, LHS 3624, LTT 16169[12]
Database references
SIMBADdata
ARICNSdata

HD 200779 (HIP 104092; Gliese 818; LHS 3624) is a solitary star located in the equatorial constellation Equuleus, the foal. It has an apparent magnitude of 8.27,[2] making it readily visible in binoculars but not to the naked eye. The object is located relatively close at a distance of 49 light years based on Gaia DR3 parallax measurements,[1] and it is approaching rapidly with a heliocentric radial velocity of −67 km/s.[5] It is classified as a high proper motion star,[12] with a total proper motion of 569 mas/yr.[1]

At its current distance, HD 200779's brightness is diminished by only six hundredths of a magnitude due to interstellar dust[13] and it has an absolute magnitude of +7.38.[6] HD 200779 is expected to come within 7.76 parsecs (25.3 ly) of the Solar System in roughly 160,000 years.[14]

HD 200779 is an ordinary K-type main-sequence star with a stellar classification of K6 V.[3] It has 68% the mass of the Sun[7] and 69% of its radius.[8] However, it only radiates 18% the luminosity of the Sun[9] from its photosphere at an effective temperature of 4,406 K,[10] giving it an orange hue. It has an iron abundance slightly above solar level at [Fe/H] = +0.05[7] and it is estimated to be 6.33 billion years old.[11] HD 200779 spins modestly with a projected rotational velocity of 5.1 km/s.[5] The star is generally considered to be chromospherically active.[3]

HD 200779 has two optical companions: a distant 11th magnitude star located 64.6" away and a 9th magnitude star located 169.4" away.[15]

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940  Gaia DR3 record for this source at VizieR.
  2. ↑ 2.0 2.1 2.2 Koen, C.; Kilkenny, D.; van Wyk, F.; Marang, F. (21 April 2010). "UBV (RI)C JHK observations of Hipparcos-selected nearby stars". Monthly Notices of the Royal Astronomical Society 403 (4): 1949–1968. doi:10.1111/j.1365-2966.2009.16182.x. ISSN 0035-8711. Bibcode: 2010MNRAS.403.1949K. 
  3. ↑ 3.0 3.1 3.2 Gray, R. O.; Corbally, C. J.; Garrison, R. F.; McFadden, M. T.; Robinson, P. E. (October 2003). "Contributions to the Nearby Stars (NStars) Project: Spectroscopy of Stars Earlier than M0 within 40 Parsecs: The Northern Sample. I.". The Astronomical Journal 126 (4): 2048–2059. doi:10.1086/378365. ISSN 0004-6256. Bibcode: 2003AJ....126.2048G. 
  4. ↑ 4.0 4.1 Roman, Nancy G. (December 1955). "A Catalogue of High-Velocity Stars.". The Astrophysical Journal Supplement Series 2: 195. doi:10.1086/190021. ISSN 0067-0049. Bibcode: 1955ApJS....2..195R. 
  5. ↑ 5.0 5.1 5.2 5.3 Tokovinin, A. A. (March 1992). "The frequency of low-mass companions to K and M stars in the solar neighbourhood.". Astronomy and Astrophysics 256: 121–132. ISSN 0004-6361. Bibcode: 1992A&A...256..121T. 
  6. ↑ 6.0 6.1 Anderson, E.; Francis, Ch. (May 2012). "XHIP: An extended hipparcos compilation". Astronomy Letters 38 (5): 331–346. doi:10.1134/S1063773712050015. ISSN 1063-7737. Bibcode: 2012AstL...38..331A. 
  7. ↑ 7.0 7.1 7.2 7.3 7.4 Ramírez, I.; Fish, J. R.; Lambert, D. L.; Allende Prieto, C. (13 August 2012). "Lithium Abundances in nearby FGK Dwarf and Subgiant Stars: Internal Destruction, Galactic Chemical Evolution, and Exoplanets". The Astrophysical Journal 756 (1): 46. doi:10.1088/0004-637X/756/1/46. ISSN 0004-637X. Bibcode: 2012ApJ...756...46R. 
  8. ↑ 8.0 8.1 Stassun, Keivan G. et al. (9 September 2019). "The Revised TESS Input Catalog and Candidate Target List". The Astronomical Journal 158 (4): 138. doi:10.3847/1538-3881/ab3467. Bibcode: 2019AJ....158..138S. 
  9. ↑ 9.0 9.1 Brown, A. G. A. (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics 616: A1. doi:10.1051/0004-6361/201833051. Bibcode: 2018A&A...616A...1G.  Gaia DR2 record for this source at VizieR.
  10. ↑ 10.0 10.1 Luck, R. Earle (13 February 2018). "Abundances in the Local Region. III. Southern F, G, and K Dwarfs". The Astronomical Journal 155 (3): 111. doi:10.3847/1538-3881/aaa9b5. Bibcode: 2018AJ....155..111L. 
  11. ↑ 11.0 11.1 Dotter, Aaron; Chaboyer, Brian; Jevremović, Darko; Kostov, Veselin; Baron, E.; Ferguson, Jason W. (September 2008). "The Dartmouth Stellar Evolution Database". The Astrophysical Journal Supplement Series 178 (1): 89–101. doi:10.1086/589654. ISSN 0067-0049. Bibcode: 2008ApJS..178...89D. 
  12. ↑ 12.0 12.1 "HD 2007799". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=HD+2007799. 
  13. ↑ Gontcharov, George A.; Mosenkov, Aleksandr V. (28 September 2017). "Verifying reddening and extinction for Gaia DR1 TGAS main sequence stars". Monthly Notices of the Royal Astronomical Society 472 (4): 3805–3820. doi:10.1093/mnras/stx2219. ISSN 0035-8711. Bibcode: 2017MNRAS.472.3805G. 
  14. ↑ Bailer-Jones, C. A. L. (19 February 2015). "Close encounters of the stellar kind". Astronomy & Astrophysics 575: A35. doi:10.1051/0004-6361/201425221. ISSN 0004-6361. Bibcode: 2015A&A...575A..35B. 
  15. ↑ Mason, Brian D.; Wycoff, Gary L.; Hartkopf, William I.; Douglass, Geoffrey G.; Worley, Charles E. (December 2001). "The 2001 US Naval Observatory Double Star CD-ROM. I. The Washington Double Star Catalog". The Astronomical Journal 122 (6): 3466–3471. doi:10.1086/323920. ISSN 0004-6256. Bibcode: 2001AJ....122.3466M. 



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