| 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−Vcolor 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 mas[1] |
| Distance | 129.2 ± 0.2 ly (39.62 ± 0.06 pc) |
| Absolute magnitude (MV) | 4.48[2] |
| Details | |
| Mass | 1.37±0.130 M☉[5] 1.03±0.05[6] M☉ |
| Radius | 1.27[7] R☉ |
| Luminosity | 1.54[7] L☉ |
| Surface gravity (log g) | 4.37±0.06[7] cgs |
| Temperature | 5,695±44[5] K |
| Metallicity [Fe/H] | 0.30±0.03[6] dex |
| Rotational velocity (v sin i) | 0.88±0.5[7] km/s |
| Age | 5.3±3.4[5] Gyr |
| Other designations | |
| Uklun,CD–58°4207,HD 102117,HIP 57291,SAO 239348[3] | |
| Database references | |
| SIMBAD | data |
HD 102117 orUklun/ˈʌklən/ is astar in the southernconstellation ofCentaurus. With anapparent visual magnitude of 7.47,[2] it is too dim to be seen withoutbinoculars or a smalltelescope. It is located at a distance of approximately 129 light years from theSun based onparallax. HD 102117 is drifting further away with aradial 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]
Thestellar classification of HD 102117 is G6V,[8] which matches thespectrum of an ordinaryG-type main-sequence star. It is roughly five[5] billion years old and is spinning with aprojected rotational velocity of 0.9 km/s.[7] The star shows only a low level ofchromospheric activity[6] and isphotometrically stable,[4] meaning it doesn't vary significantly in brightness. It appearsmetal-enriched,[4] showing a higher abundance of heavy elements compared to the Sun.
In 2004, theAnglo-Australian Planet Search announced a planet orbiting the star.[4] A short time later theHARPS team also announced the presence of a planet around this star. Both groups detected this planet with theradial velocity method.[6]
HD 102117, and its planet HD 102117b, were chosen as part of the 2019NameExoWorlds campaign organised by theInternational Astronomical Union, which assigned each country a star and planet to be named. HD 102117 was assigned toPitcairn Islands. The winning proposal named the starUklun, from the wordaklan 'we/us' in thePitcairn language, and the planetLeklsullun/lɛkəlsʌlən/, from the phraselekl salan 'child/children' (lit. 'little person').[9]
| Companion (in order from star) | Mass | Semimajor axis (AU) | Orbital period (days) | Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b / Leklsullun | 0.172 ± 0.020 MJ | 0.1532 ± 0.0088 | 20.8133 ± 0.0064 | 0.121 ±0.082 | — | — |
