The designation Gliese 486 comes from the Gliese Catalogue of Nearby Stars. This was the 486th star listed in the first edition of the catalogue.
In August 2022, this planetary system was included among 20 systems to be named by the third NameExoWorlds project.[8] The approved names, proposed by a team from Spain, were announced in June 2023. Gliese 486 is named Gar and its planet is named Su, after the Basque words for "flame" and "fire".[9]
Properties
Gliese 486 has a surface temperature of 3340±54 K. Gliese 486 is similar to the Sun in its concentration of heavy elements, with a metallicity Fe/H index of 0.07±0.16. It was suspected to be a flare star,[10] although measurements available in 2019 did not reveal any flares.[11] The chemical makeup of the star is unremarkable and consistent with solar abundances or being slightly metal-poor.[5]
The star has an unremarkable magnetic field in the chromosphere of about 1.6 kilogauss.[6] It is rotating very slowly and is likely to be very old, belonging kinematically to the old thin disk of the Milky Way.[12]
Multiplicity surveys did not detect any stellar companions to Gliese 486 as of 2020.[13]
Planetary system
Artistic impression of the surface of the hot super-Earth Gliese 486b.Artist's impression and size comparison of Gliese 486b and Earth. In reality, the exoplanet likely has little to no atmosphere.
In 2021, one planet, named Gliese 486 b, was discovered on a tight, circular orbit.[7] It represents a rare class of rocky exoplanet suitable for spectroscopic characterization in the near future[14] by the James Webb Space Telescope.[15] By 2022, no hydrogen or steam dominated atmosphere was detected, although a secondary planetary atmosphere with a higher molecular weight remained a possibility.[16] Observations by JWST announced in 2023 detected signs of water vapor, but it was unclear if this is from the planet's atmosphere or from its host star.[17][18]
Secondary eclipse observations by JWST published in 2024 show a planetary dayside temperature of 865±14 K (592 °C; 1,097 °F). This is consistent with a lack of heat redistribution, indicating that the planet likely has little to no atmosphere and the previous water vapor detection was likely a result of contamination from the host star. Gliese 486 b is thus similar to other hot rocky planets around red dwarfs, such as LHS 3844 b, GJ 1252 b, TRAPPIST-1b, and GJ 1132 b.[4]
^Bozhinova, I.; Helling, Ch.; Scholz, A. (2014), "Planetary host stars: Evaluating uncertainties in cool model atmospheres", Monthly Notices of the Royal Astronomical Society, 450 (1): 160–182, arXiv:1405.5416, Bibcode:2015MNRAS.450..160B, doi:10.1093/mnras/stv613
^ abcMansfield, Megan Weiner; Xue, Qiao; Zhang, Michael; Mahajan, Alexandra S.; Ih, Jegug; Koll, Daniel; Bean, Jacob L.; Coy, Brandon Park; Eastman, Jason D.; Kempton, Eliza M.-R.; Kite, Edwin S.; Lunine, Jonathan (2024). "No Thick Atmosphere on the Terrestrial Exoplanet GI 486b". arXiv:2408.15123.
