HD 172051

HD 172051 (86 G. Sagittarii) is a single,[10] yellow-hued star in the southern constellation of Sagittarius. The star is barely bright enough to be seen with the naked eye, having an apparent visual magnitude of 5.85.[2] Based upon an annual parallax shift of 76.64 mas, it is located some 43 light years from the Sun. It is moving away from the Sun with a radial velocity of +37 km/s.[1]

HD 172051
Observation data
Epoch J2000      Equinox J2000
Constellation Sagittarius
Right ascension 18h 38m 53.40151s[1]
Declination −21° 03′ 06.7415″[1]
Apparent magnitude (V) 5.85[2]
Characteristics
Spectral type G5 V[2]
B−V color index 0.68[3]
Astrometry
Radial velocity (Rv)+37.14±0.20[1] km/s
Proper motion (μ) RA: −75.128±0.163[1] mas/yr
Dec.: −153.645±0.150[1] mas/yr
Parallax (π)76.6355 ± 0.1082[1] mas
Distance42.56 ± 0.06 ly
(13.05 ± 0.02 pc)
Absolute magnitude (MV)5.27[4]
Details
Mass0.865[5] or 1.00[6] M☉
Radius0.90[5] R☉
Surface gravity (log g)4.65[2] cgs
Temperature5,638[2] K
Metallicity [Fe/H]–0.21[2] dex
Rotational velocity (v sin i)0.32[7] km/s
Age4.1–4.8[8] Gyr
Other designations
86 G. Sagittarii, BD−21° 5081, GJ 722, HD 172051, HIP 91438, HR 6998, SAO 187086, WDS J18389-2103AB[9]
Database references
SIMBADdata

This ordinary G-type main-sequence star is considered a solar analog, having physical properties sufficiently similar to the Sun. It has a stellar classification of G5 V[2] and is around 4.5 billion years old. 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.[11] 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.[12]

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.
  2. 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. 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, arXiv:0811.3982, Bibcode:2009A&A...501..941H, doi:10.1051/0004-6361/200811191.
  5. 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, arXiv:astro-ph/0607235, Bibcode:2007ApJS..168..297T, doi:10.1086/509763
  6. 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, arXiv:1211.7263, Bibcode:2013A&A...552A..78Z, doi:10.1051/0004-6361/201116551, A78.
  7. 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" (PDF). Astronomy and Astrophysics. 520: A79. arXiv:1002.4391. Bibcode:2010A&A...520A..79M. doi:10.1051/0004-6361/200913725.
  8. 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.
  9. "HD 172051". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved November 15, 2018.
  10. 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.
  11. "Planet hunters target nearby star". BBC News. 2003-11-07. Retrieved 2006-08-04.
  12. 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, arXiv:1007.4315, Bibcode:2010PASP..122.1195T, doi:10.1086/656481.

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