HD 102117

HD 102117 or Uklun /ˈʌklən/ is a star in the southern constellation of Centaurus. With an apparent visual magnitude of 7.47,[2] it is too dim to be seen without binoculars or a small telescope. It is located at a distance of approximately 129 light years from the Sun based on parallax. HD 102117 is drifting further away with a radial velocity of +50 km/s,[1] having come to within 43.9 light-years some 692,000 years ago.[2] It has one known planet.[6]

HD 102117
Observation data
Epoch J2000      Equinox J2000
Constellation Centaurus
Right ascension 11h 44m 50.46084s[1]
Declination –58° 42′ 13.3564″[1]
Apparent magnitude (V) 7.47[2]
Characteristics
Spectral type G6V[3]
B−V color index 0.721±0.009[2]
Variable type Constant[4]
Astrometry
Radial velocity (Rv)+49.64±0.13[1] km/s
Proper motion (μ) RA: –63.555[1] mas/yr
Dec.: –70.439[1] mas/yr
Parallax (π)25.2369 ± 0.0409[1] mas
Distance129.2 ± 0.2 ly
(39.62 ± 0.06 pc)
Absolute magnitude (MV)4.48[2]
Details
Mass1.37±0.130 M☉[5]
1.03±0.05[6] M☉
Radius1.27[7] R☉
Luminosity1.54[7] L☉
Surface gravity (log g)4.37±0.06[7] cgs
Temperature5,695±44[5] K
Metallicity [Fe/H]0.30±0.03[6] dex
Rotational velocity (v sin i)0.88±0.5[7] km/s
Age5.3±3.4[5] Gyr
Other designations
Uklun, CD–58°4207, HD 102117, HIP 57291, SAO 239348[3]
Database references
SIMBADdata
Extrasolar Planets
Encyclopaedia		data

The stellar classification of HD 102117 is G6V,[8] which matches the spectrum of an ordinary G-type main-sequence star. It is roughly five[5] billion years old and is spinning with a projected rotational velocity of 0.9 km/s.[7] The star shows only a low level of chromospheric activity[6] and is photometrically stable,[4] meaning it doesn't vary significantly in brightness. It appears metal-enriched,[4] showing a higher abundance of heavy elements compared to the Sun.

Planetary system

In 2004, the Anglo-Australian Planet Search announced a planet orbiting the star.[4] A short time later the HARPS team also announced the presence of a planet around this star. Both groups detected this planet with the radial velocity method.[6]

HD 102117, and its planet HD 102117b, were chosen as part of the 2019 NameExoWorlds campaign organised by the International Astronomical Union, which assigned each country a star and planet to be named. HD 102117 was assigned to Pitcairn Islands. The winning proposal named the star Uklun, from the word aklan 'we/us' in the Pitcairn language, and the planet Leklsullun /lɛkəlsʌlən/, from the phrase lekl salan 'child/children' (lit. 'little person').[9]

The HD 102117 planetary system[10]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b 0.172 ± 0.020 MJ 0.1532 ± 0.0088 20.8133 ± 0.0064 0.121 ±0.082 — —

See also

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. Gaia DR2 record for this source at VizieR.
  2. Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015, S2CID 119257644
  3. "HD 102117". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2021-01-28.
  4. Tinney, C. G.; et al. (2005). "Three Low-Mass Planets from the Anglo-Australian Planet Search". The Astrophysical Journal. 623 (2): 1171–1179. Bibcode:2005ApJ...623.1171T. CiteSeerX 10.1.1.491.2941. doi:10.1086/428661.
  5. Valenti, Jeff A.; Fischer, Debra A. (July 2005), "Spectroscopic Properties of Cool Stars (SPOCS). I. 1040 F, G, and K Dwarfs from Keck, Lick, and AAT Planet Search Programs", The Astrophysical Journal Supplement Series, 159 (1): 141–166, Bibcode:2005ApJS..159..141V, doi:10.1086/430500
  6. Lovis, C.; et al. (2005). "The HARPS search for southern extra-solar planets III. Three Saturn-mass planets around HD 93083, HD 101930 and HD 102117". Astronomy and Astrophysics. 437 (3): 1121–1126. arXiv:astro-ph/0503660. Bibcode:2005A&A...437.1121L. doi:10.1051/0004-6361:20052864. S2CID 119492030.
  7. "SPOCS I", Exoplanets, Yale University, retrieved 2012-01-31
  8. Houk, Nancy (1979). Michigan catalogue of two-dimensional spectral types for the HD stars. 1. Ann Arbor, Michigan: Department of Astronomy, University of Michigan. Bibcode:1978mcts.book.....H.
  9. "Pitcairn Islands". NameExoworlds. Retrieved 2019-12-30.
  10. Butler, R. P.; et al. (2006). "Catalog of Nearby Exoplanets". The Astrophysical Journal. 646 (1): 505–522. arXiv:astro-ph/0607493. Bibcode:2006ApJ...646..505B. doi:10.1086/504701. S2CID 119067572.

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