Regulus
Star
Regulus — the 'little king' at the heart of Leo the Lion, about 79 light-years away and the faintest of the 1st-magnitude stars. It spins so fast — a full turn in under 16 hours — that it bulges at the equator into a squashed, egg-like shape, cooler and dimmer around its waist than at its poles.
Open in 3D viewSee Regulus in the live, interactive 3D map
Key facts
Mass
7.56 × 10³⁰ kg
3.8 M☉
Radius
2,782,800 km
4× wider than the Sun
Surface temperature
11,700 K (11427 °C)
Luminosity
1.21 × 10²⁹ W
Spectral type
B8 IVn (rapidly-rotating blue-white star)
Science
Physical
- Mass
- 7.56 × 10³⁰ kg · 3.8 M☉
- Radius
- 2,782,800 km · 4× wider than the Sun
- Density
- 83.7 kg/m³ · 0.084× water
- Spectral type
- B8 IVn (rapidly-rotating blue-white star)
Composition
- By mass
- A hot blue-white star rotating near its break-up speed — one turn in under 16 hours — so it bulges at the equator and is cooler and fainter there (gravity darkening). It has a white-dwarf companion plus two fainter stars. The figures here are for Regulus A; its temperature varies from pole to equator.
Temperature
- Surface
- 11,700 K (11427 °C)
Radiation & temperature
- Surface temperature
- 11,700 K (11427 °C)
- Peak wavelength
- 248 nm · ultraviolet (invisible to the eye)
Discovery & history
- Method
- Naked-eye star
- Name
- 'Regulus' — the little king (Latin, diminutive of rex); Alpha Leonis, the Lion's heart (Cor Leonis).
One of the four 'royal stars' of ancient Persia that marked the seasons. Sitting close to the ecliptic, it is regularly passed — and occasionally hidden — by the Moon and planets; interferometry has measured its rapid rotation and oblate shape.
Images
Images from open archives · credit shown per image