XO-5

XO-5, formally named Absolutno, is a likely binary star system, made up of a G-type dwarf and a red dwarf companion, located approximately 893 light-years away from Earth in the Lynx constellation. It has a magnitude of about 12 and cannot be seen with the naked eye but is visible through a small telescope.
XO-5 has a suspected red dwarf companion with a temperature of 3500 K, on a wide orbit. A 2024 study also identified it as a very likely binary star, with 94% probability.
The name Absolutno was selected in the NameExoWorlds campaign by the Czech Republic, during the 100th anniversary of the IAU. Absolutno is a fictional miraculous substance in the Czech sci-fi novel Továrna na absolutno.

Planetary system

The exoplanet XO-5b was discovered by the XO Telescope using the transit method in 2008. This planet is classified as a hot Jupiter. A search for transit timing variations caused by additional planets was negative.