The brightest white dwarf star is Sirius B. It is part of the binary star system Sirius, which includes the much brighter main-sequence star, Sirius A.
Sirius B was discovered in 1862 and has a surface temperature of about 25,000 K, making it incredibly hot for a white dwarf. Its brightness comes from the fact that it is relatively close to our solar system, at a distance of approximately 8.6 light-years, which allows us to observe it with a greater intensity.
Although Sirius B is not visible to the naked eye due to its faintness compared to Sirius A, it can be observed with the help of telescopes. Its high luminosity among white dwarfs is attributed to both its temperature and its proximity to Earth.