Flare star
Proxima Centauri is closer to the sun than any other star and is a flare star. Proxima Centauri increases its brightness randomly and magnetic force causes this. Convection creates a magnetic field throughout the matter in Proxima Centauri, and this leads to flaring with a total X-ray output similar to that of the Sun though the sun is much more massive (heavier) than Proxima Centauri.