HD 165185

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HD 165185
Observation data
Epoch J2000      Equinox J2000
Constellation Sagittarius
Right ascension 18h 06m 23.71908s[1]
Declination –36° 01′ 11.2389″[1]
Apparent magnitude (V) 5.94[2]
Spectral type G1 V[2]
U−B color index 0.07[3]
B−V color index 0.61[3]
Radial velocity (Rv)+15.4[2] km/s
Proper motion (μ) RA: +105.05[1] mas/yr
Dec.: +7.95[1] mas/yr
Parallax (π)56.97 ± 0.48[1] mas
Distance57.3 ± 0.5 ly
(17.6 ± 0.1 pc)
Absolute magnitude (MV)+4.59[4]
Mass1.13[5] M
Radius0.94[6] R
Luminosity (bolometric)1.15[7] L
Surface gravity (log g)4.46±0.06[8] cgs
Temperature5,940±18[8] K
Metallicity [Fe/H]−0.05±0.03[8] dex
Rotation5.90[6] days
Rotational velocity (v sin i)7.53[8] km/s
Age437±186[5] Myr
Other designations
29 G. Sgr,[9] CD-36° 12214, GJ 702.1, HD 165185, HIP 88694, HR 6748, SAO 209710, WDS J18064-3601A.[10]
Database references

HD 165185 is the Henry Draper Catalogue designation for a star in the southern zodiac constellation of Sagittarius. It has an apparent visual magnitude of 5.94,[2] which indicates it is a sixth magnitude star that is faintly visible to the naked eye. (According to the Bortle scale, it can be viewed from dark suburban skies.) Parallax measurements by the Hipparcos spacecraft give an estimated distance of 57.3 light years away.[1]

This star is a pre-main-sequence[11] solar analog[12] with a stellar classification of G1 V.[2] It is spinning rapidly with a projected rotational velocity of 7.53 km/s[8] and a rotation period of 5.9 days.[6] Measurements of magnetic activity in the chromosphere show variations over time, much like the sunspot cycle. This activity showed a distinct peak in 2009.[13] Stellar models give an estimated mass equal to 1.13[5] times the mass of the Sun, but only 94%[6] of the Sun's radius. The total, or bolometric luminosity of the star is 15% higher than the Sun,[7] while the abundance of elements other than hydrogen and helium—what astronomer's term the metallicity—is nearly the same as in the Sun.[8] The stellar atmosphere has an effective temperature of 5,940[8] K, giving it the yellow-hued glow of a G-type star.[14]

HD 165185 completed its perihelion passage some 851,000 years ago when it came within 29 ly (8.9 pc) of the Sun,[15] and it is now moving away with a radial velocity component of 15.4 km/s.[2] Based upon the motion of this star through space, its age, and properties, this star is a probable member of the Ursa Major Moving Group; a stellar kinematic group that formed in the same region of space.[11] It has a suspected common proper motion companion at an angular separation of 12, corresponding to a projected separation of 220 AU. This is a red dwarf star with a stellar classification of M0 and an infrared K band magnitude of 8.11.[16]


  1. ^ a b c d e f 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 f Torres, C. A. O.; et al. (December 2006). "Search for associations containing young stars (SACY). I. Sample and searching method". Astronomy and Astrophysics. 460 (3): 695–708. arXiv:astro-ph/0609258. Bibcode:2006A&A...460..695T. doi:10.1051/0004-6361:20065602.
  3. ^ a b Stobie, R. S. (1970), "Photometry of bright southern cepheids", Monthly Notices of the Royal Astronomical Society, 148: 1–15, Bibcode:1970MNRAS.148....1S, doi:10.1093/mnras/148.1.1.
  4. ^ Eggen, Olin J. (August 1998), "The Sirius Supercluster and Missing Mass near the Sun", The Astronomical Journal, 116 (2): 782–788, Bibcode:1998AJ....116..782E, doi:10.1086/300465.
  5. ^ a b c Plavchan, Peter; et al. (June 2009), "New Debris Disks Around Young, Low-Mass Stars Discovered with the Spitzer Space Telescope", The Astrophysical Journal, 698 (2): 1068–1094, arXiv:0904.0819, Bibcode:2009ApJ...698.1068P, doi:10.1088/0004-637X/698/2/1068.
  6. ^ a b c d Linsky, Jeffrey L.; et al. (July 2012), "Ultraviolet Spectroscopy of Rapidly Rotating Solar-Mass Stars: Emission-line Redshifts as a Test of the Solar-Stellar Connection", The Astrophysical Journal, 754 (1): 14, arXiv:1205.6498, Bibcode:2012ApJ...754...69L, doi:10.1088/0004-637X/754/1/69, 69.
  7. ^ a b Léger, Alain; et al. (August 2015), "Impact of ηEarth on the Capabilities of Affordable Space Missions to Detect Biosignatures on Extrasolar Planets", The Astrophysical Journal, 808 (2): 19, arXiv:1504.08232, Bibcode:2015ApJ...808..194L, doi:10.1088/0004-637X/808/2/194, 194.
  8. ^ a b c d e f g Tsantaki, M.; et al. (October 2014), "Spectroscopic parameters for solar-type stars with moderate-to-high rotation. New parameters for ten planet hosts", Astronomy & Astrophysics, 570: 14, arXiv:1407.6765, Bibcode:2014A&A...570A..80T, doi:10.1051/0004-6361/201424257, A80.
  9. ^ B. A., Gould (1879), Resultados del Observatorio Nacional Argentino en Cordoba, 1, retrieved 2016-04-05.
  10. ^ "HD 165185 -- Pre-main sequence Star", SIMBAD Astronomical Database, Centre de Données astronomiques de Strasbourg.
  11. ^ a b Nakajima, Tadashi; Morino, Jun-Ichi (January 2012), "Potential Members of Stellar Kinematic Groups within 30 pc of the Sun", The Astronomical Journal, 143 (1): 2, Bibcode:2012AJ....143....2N, doi:10.1088/0004-6256/143/1/2.
  12. ^ Gaidos, Eric J.; Gonzalez, Guillermo (July 2002), "Stellar atmospheres of nearby young solar analogs", New Astronomy, 7 (5): 211–226, arXiv:astro-ph/0203518, Bibcode:2002NewA....7..211G, doi:10.1016/S1384-1076(02)00108-2.
  13. ^ Metcalfe, T. S.; et al. (September 2009), "Activity Cycles of Southern Asteroseismic Targets", Proceedings of the "Solar Analogs II" workshop, arXiv:0909.5464, Bibcode:2009arXiv0909.5464M.
  14. ^ "The Colour of Stars", Australia Telescope, Outreach and Education, Commonwealth Scientific and Industrial Research Organisation, December 21, 2004, retrieved 2012-01-16.
  15. ^ Bailer-Jones, C. A. L. (March 2015), "Close encounters of the stellar kind", Astronomy & Astrophysics, 575: 13, arXiv:1412.3648, Bibcode:2015A&A...575A..35B, doi:10.1051/0004-6361/201425221, A35.
  16. ^ Chini, R.; et al. (January 2014), "New visual companions of solar-type stars within 25 pc", Monthly Notices of the Royal Astronomical Society, 437 (1): 879–886, arXiv:1310.2684, Bibcode:2014MNRAS.437..879C, doi:10.1093/mnras/stt1953.