Gliese 686 (GJ 686 / HIP 86287 / LHS 452)[6] is a star in the constellation of Hercules, with an apparent magnitude +9.577.[3] Although it is close to the Solar System – at 26.6 light-years – it is not the closest known star in its constellation, since Gliese 661 is 20.9 light years away.[7] The closest system to this star is the bright μ Herculis, at 4.5 light years. They are followed by GJ 1230 and Gliese 673, at 7.2 and 7.6 light years respectively.[8]
Gliese 686 is one of the many red dwarfs in the Solar System neighborhood with a spectral type of M1V,[3][6] and has an effective temperature of about 3600 K.[3] Its brightness in the visible spectrum is equal to 0.82% of that of the Sun,[9] while its total luminosity is equivalent to 2.7% that of the Sun,[10] since a significant amount of the radiation emitted by these stars is infrared invisible light. Considering only this last parameter, Gliese 686 is considerably brighter than other known red dwarfs: it is 6.5 times more luminous than Ross 154 and 15 times more than Proxima Centauri, the closest star to the Solar System.
Gliese 686 has a radius approximately half that of the Sun. Its projected rotation speed is 2.5 km / s, its rotation period being equal to or less than 10.3 days.[11] It has a metallic content lower than that of the Sun; various studies estimate its index metallicity between -0.25 and -0.44.[11][12] It has an approximate mass between 45% and 49% of the solar mass[13] and is a star with characteristics comparable to that of Lacaille 9352.
Planetary system
Gliese 686 has one known super-Earth planet detected by radial velocity.[3] It is orbiting close to the host star with a separation of 0.091 AU (13.6 Gm) and an orbital period of 15.5 days. Since the inclination of its orbit is unknown, only a lower bound on its mass can be determined: it has at least 6.6 times the mass of the planet Earth.
^ abcBurt, Jennifer A.; Feng, Fabo; Holden, Bradford; Mamajek, Eric E.; Huang, Chelsea X.; Rosenthal, Mickey M.; Wang, Songhu; Paul Butler, R.; Vogt, Steven S.; Laughlin, Gregory; Henry, Gregory W.; Teske, Johanna K.; Wang, Sharon W.; Crane, Jeffrey D.; Shectman, Steve A. (2021), "A Collage of Small Planets from the Lick–Carnegie Exoplanet Survey: Exploring the Super-Earth and Sub-Neptune Mass Regime", The Astronomical Journal, 161 (1): 10, arXiv:2011.08867, Bibcode:2021AJ....161...10B, doi:10.3847/1538-3881/abc2d0, S2CID227013469
^Nidever, David L.; Marcy, Geoffrey W.; Butler, R. Paul; Fischer, Debra A.; Vogt, Steven S.; McGahee, C. E.; O'Donoghue, A. A.; Knox, E. R. (2002). "Radial Velocities for 889 Late-Type Stars". The Astrophysical Journal Supplement Series. 141 (2): 503–522. arXiv:astro-ph/0112477. Bibcode:2002ApJS..141..503N. doi:10.1086/340570. S2CID51814894.
