Most flare stars are dim red dwarfs, although less massive (lighter) brown dwarfs might also be able to flare. The more massive (heavier) RS Canum Venaticorum variables (RS CVn) are also known to flare, but scientists understand that a companion star in a binary system causes these flares. This companion star disturbs the magnetic field. Nine stars similar to the Sun have also been seen to flare. There is a suggestion that this happens for similar reasons to the flares of the RS CVn variables. A companion causes the flares, this companion is a massive planet like the planet Jupiter that orbits the flaring star closely.