HD 172051

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HD 172051
Observation data
Epoch J2000      Equinox J2000
Constellation Sagittarius
Right ascension 18h 38m 53.40045s[1]
Declination −21° 03′ 06.7368″[1]
Apparent magnitude (V) 5.85[2]
Spectral type G5 V[2]
B−V color index 0.68[3]
Radial velocity (Rv) +37.13[4] km/s
Proper motion (μ) RA: –74.85 ± 0.77[1] mas/yr
Dec.: –152.00 ± 0.47[1] mas/yr
Parallax (π) 76.43 ± 0.47[1] mas
Distance 42.7 ± 0.3 ly
(13.08 ± 0.08 pc)
Surface gravity (log g) 4.65[2] cgs
Temperature 5,638[2] K
Metallicity [Fe/H] –0.21[2] dex
Rotational velocity (v sin i) 0.32[5] km/s
Age 4.1–4.8[6] Gyr
Other designations
86 G. Sagittarii, BD -21°5081, GCTP 4289.01, GJ 722, HD 172051, HIP 91438, HR 6998, SAO 187086.

HD 172051 (86 G. Sagittarii) is a main sequence star in the constellation Sagittarius. It is located about 42 light years from the Sun and is considered a solar analog. The mass is similar to the Sun, although it is cooler and has a lower luminosity. Due to this similarity, HD 172051 has been selected as an early target star for both the Terrestrial Planet Finder and Darwin missions, which seek to find an Earth-like extrasolar planet.[7]


  1. ^ a b c d e van Leeuwen, F. (November 2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. 
  2. ^ a b c d e Maldonado, J. et al. (May 2012). "Metallicity of solar-type stars with debris discs and planets". Astronomy & Astrophysics 541: A40. arXiv:1202.5884. Bibcode:2012A&A...541A..40M. doi:10.1051/0004-6361/201218800. 
  3. ^ Corben, P. M.; Stoy, R. H. (1968), "Photoelectric Magnitudes and Colours for Bright Southern Stars", Monthly Notes of the Astronomical Society of Southern Africa 27: 11, Bibcode:1968MNSSA..27...11C. 
  4. ^ Nidever, David L. et al. (August 2002), "Radial Velocities for 889 Late-Type Stars", The Astrophysical Journal Supplement Series 141 (2): 503–522, arXiv:astro-ph/0112477, Bibcode:2002ApJS..141..503N, doi:10.1086/340570 
  5. ^ Martínez-Arnáiz, R. et al. (September 2010). "Chromospheric activity and rotation of FGK stars in the solar vicinity. An estimation of the radial velocity jitter". Astronomy and Astrophysics 520: A79. arXiv:1002.4391. Bibcode:2010A&A...520A..79M. doi:10.1051/0004-6361/200913725. 
  6. ^ Mamajek, Eric E.; Hillenbrand, Lynne A. (November 2008). "Improved Age Estimation for Solar-Type Dwarfs Using Activity-Rotation Diagnostics". The Astrophysical Journal 687 (2): 1264–1293. arXiv:0807.1686. Bibcode:2008ApJ...687.1264M. doi:10.1086/591785. 
  7. ^ "Planet hunters target nearby star". BBC News. 2003-11-07. Retrieved 2006-08-04. 

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