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)
Absolute magnitude (MV) 5.27[5]
Mass 0.865[6] or 1.00[7] M
Radius 0.90[6] R
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[8] km/s
Age 4.1–4.8[9] Gyr
Other designations
86 G. Sagittarii, BD -21°5081, GCTP 4289.01, GJ 722, HD 172051, HIP 91438, HR 6998, SAO 187086.
Database references

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.[10]

During a search for brown dwarf companions using the Hale telescope in 2004, two candidate companions were identified at angular separations of 5″ and 6″. However, these were determined to be background stars.[11]


  1. ^ a b c d e van Leeuwen, F. (November 2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. Bibcode:2007A&A...474..653V. arXiv:0708.1752Freely accessible. 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. Bibcode:2012A&A...541A..40M. arXiv:1202.5884Freely accessible. 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, Bibcode:2002ApJS..141..503N, arXiv:astro-ph/0112477Freely accessible, doi:10.1086/340570 
  5. ^ Holmberg, J.; et al. (July 2009), "The Geneva-Copenhagen survey of the solar neighbourhood. III. Improved distances, ages, and kinematics", Astronomy and Astrophysics, 501 (3): 941–947, Bibcode:2009A&A...501..941H, arXiv:0811.3982Freely accessible, doi:10.1051/0004-6361/200811191. 
  6. ^ a b Takeda, Genya; et al. (February 2007), "Structure and Evolution of Nearby Stars with Planets. II. Physical Properties of ~1000 Cool Stars from the SPOCS Catalog", The Astrophysical Journal Supplement Series, 168 (2): 297–318, Bibcode:2007ApJS..168..297T, arXiv:astro-ph/0607235Freely accessible, doi:10.1086/509763 
  7. ^ Zechmeister, M.; et al. (April 2013), "The planet search programme at the ESO CES and HARPS. IV. The search for Jupiter analogues around solar-like stars", Astronomy & Astrophysics, 552: 62, Bibcode:2013A&A...552A..78Z, arXiv:1211.7263Freely accessible, doi:10.1051/0004-6361/201116551, A78. 
  8. ^ 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. Bibcode:2010A&A...520A..79M. arXiv:1002.4391Freely accessible. doi:10.1051/0004-6361/200913725. 
  9. ^ 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. Bibcode:2008ApJ...687.1264M. arXiv:0807.1686Freely accessible. doi:10.1086/591785. 
  10. ^ "Planet hunters target nearby star". BBC News. 2003-11-07. Retrieved 2006-08-04. 
  11. ^ Tanner, Angelle M.; et al. (October 2010), "A High-Contrast Imaging Survey of SIM Lite Planet Search Targets", Publications of the Astronomical Society of the Pacific, 122 (896): 1195–1206, Bibcode:2010PASP..122.1195T, arXiv:1007.4315Freely accessible, doi:10.1086/656481. 

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