Regulus is a hot, blue B7V main sequence star having a luminosity about 140 times that of the sun and about 3.4 times the diameter. The spectral type implies an effective temperature of 13,000 K and a diameter about 3 times that of the sun.
This star is in fact the A component of a multiple star system. The B and C components are a close binary pair revolving together with a separation of 4.2 arc sec from A. This corresponds to a separation of about 100 AU, that is, two and a half times the distance between the sun and Pluto. The period is 2000 years.
Regulus B is an orange K1V main sequence star having a Apparent Magnitude of 8.13. This star has slightly more than 1/4 of the luminosity of the sun, 70% of the sun's mass, and 80% of the sun's radius.
Regulus C is a 13th magnitude dwarf having a luminosity of 1/330 of that of the sun.