Regulus is not really a single star, but a multiple star system. It consists of two pairs of stars. Regulus A, the primary component in the Regulus system, is a spectroscopic binary star composed of a blue-white main sequence star with the spectral classification B7 V and a companion believed to be a white dwarf. With a visual magnitude of 1.35, Regulus A is reponsible for the star system’s brightness and bluish colour. The system lies approximately 79 light years from the Sun.

Leo I is a dwarf spheroidal galaxy in the constellation Leo. At about 820,000 light-years distant, it is a member of the Local Group of galaxies and is thought to be one of the most distant satellites of the Milky Way galaxy.

Leo I is located only 12 arc minutes from Regulus. For that reason, the galaxy is sometimes called the „Regulus Dwarf“. Scattered light from the star makes studying the galaxy more difficult, and it was not until the 1990s that it was detected visually. Typical to a dwarf galaxy, the metallicity of Leo I is very low, only one percent that of the Sun. The galaxy may be embedded in a cloud of ionized gas with a mass similar to that of the whole galaxy.