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Basilicus, Kalb, Alpha Leonis, 32 Leonis

Proper NamesRegulus, Basilicus, Kalb
Bayer DesignationAlpha Leonis
Flamsteed Number32 Leonis
HR (BSC)3982
Right Ascension10h 8m 22s
Declination+11° 58' 2"
Distance79 light years
24 parsecs
MagnitudeApparent: +1.4
Absolute: -0.5
Spectral ClassB7V blue main sequence star
Optimum VisibilityMarch
NotesRegulus is a complex star system with at least four members. The primary blue dwarf star Regulus A forms a close binary pair with a companion star, thought to be a white dwarf. Around Regulus A and its companion, a second binary pair orbits at a distance of some 5,000 AU.

The faint and hazy patch of light directly northward from Regulus is Leo I, a dwarf spheroidal galaxy some 820,000 light years distant. Leo I is thought to be a satellite galaxy of the Milky Way, and if so this would make it most distant such satellite of the Galaxy known. Imagery provided by Aladin sky atlas

Location of Regulus

Regulus lies almost exactly on the Ecliptic, the apparent path of the Sun through the sky. This means that, once each year, the Sun will appear to pass directly in front of the star, an event which happens on or about the 22 August.

Image of Regulus

A comet pursues its lonely course around Regulus, the 'Royal Star' of Leo.

This blue dwarf star is slightly variable, but is always bright from an Earth-bound observer's perspective, with an apparent magnitude varying around +1.3. Regulus is also notable for lying almost exactly on the line of the Ecliptic.


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