What kind of star is Regulus?
Regulus, catalogued as Alpha Leonis (α Leo), appears in the official constellation Leo. Its apparent visual magnitude is 1.35, while its estimated distance is about 79 light-years. Astronomers classify the object as B8 IVn. These labels describe temperature, luminosity class or system components; they should not be read as a claim that every naked-eye point is a single isolated star.
Regulus A is a hot B-type star spinning so rapidly that centrifugal force makes its equator wider and cooler than its poles. Interferometry and rotational modelling therefore give a more realistic picture than a single spherical temperature or radius. Radial-velocity measurements reveal a close, unseen low-mass companion in an orbit of roughly forty days; evolutionary work commonly interprets it as a white dwarf that previously transferred mass and spun Regulus up. Farther away, two faint stars form another pair, making the complete system hierarchical. Regulus lies near the ecliptic only by viewing geometry, which is why lunar occultations are possible; that position has no causal connection with the system's unusual rotation.
The coordinate pair RA 10h 08m 22.31s, Dec +11° 58′ 01.9″ fixes the object's direction on the celestial sphere for the J2000 reference epoch. Right ascension works like celestial longitude measured in hours, while declination works like latitude north or south of the celestial equator. Proper motion and improved measurements can refine catalogue positions, but these coordinates are sufficiently precise for a finder chart or planetarium search.
Regulus data at a glance
| Proper name | Regulus | Catalogue designation | Alpha Leonis (α Leo) |
|---|---|---|---|
| Constellation | Leo | Apparent magnitude | 1.35 |
| Spectral or system type | B8 IVn | Estimated distance | about 79 light-years |
| Right ascension (J2000) | 10h 08m 22.31s | Declination (J2000) | +11° 58′ 01.9″ |
Values are rounded for an observer-friendly overview. Consult the linked SIMBAD record for component-level identifiers, bibliography, measurement provenance and newer catalogue values.
The name Regulus
Latin for “little king” or “prince.” It is also historically known as Cor Leonis, the Lion’s Heart.
Long before modern Leo boundaries, Mesopotamian sky traditions treated this region as royal, and Greek writers used a name meaning “little king.” The Latin Regulus became standard in European catalogues, while Cor Leonis preserved the anatomical idea of the Lion's Heart. Astrologers counted it among four “royal stars,” but that cultural category is not a scientific classification. Twentieth-century spectroscopy and later optical interferometry replaced the old picture of a single round star with today's rapid-rotator and multiple-system model.
Modern professional catalogues retain identifiers such as the Bayer designation alongside a proper name. The International Astronomical Union standardizes which name belongs to which component—an important distinction for systems whose combined light looks like one star from Earth.
How to find Regulus
Find the Sickle of Leo, shaped like a reversed question mark. Regulus is the bright star at its base. Its position near the ecliptic makes lunar conjunctions and occultations particularly worthwhile.
Visible from most inhabited latitudes; especially prominent during northern late winter and spring. Visibility on a particular night still depends on latitude, season, time, horizon obstructions, weather and local light pollution. Use the interactive atlas below to check the surrounding field before observing.
Observation checklist
- Look at the bottom of Leo's backward-question-mark Sickle from February through May.
- Compare its blue-white light with orange Algieba higher in the Sickle.
- Watch for close Moon–Regulus conjunctions because the star lies near the ecliptic.
- The stellar companions are not a practical small-telescope split despite the point's naked-eye brightness.
Interesting facts about Regulus
- Regulus lies less than half a degree from the ecliptic, so the Moon and occasionally planets pass in front of it.
- Its hot primary rotates rapidly, producing an oblate star with a cooler equator and hotter poles.
- Regulus is a multiple system with a close faint companion and a more distant pair.
- It is Leo’s brightest star and marks the Lion’s heart.
- The star is easy to see from suburban locations without optical aid.
Continue from Regulus into the night sky
Use the Leo constellation guide to place this star within its larger pattern. When you are ready to observe, compare dark-sky places, find a nearby observatory, or follow our practical guide to finding a star in the night sky. Symbolically registered names are kept separately in the searchable Star-Register catalogue.
Sources and further reading
Measurements are rounded for readability. Multiple systems, variable stars and distant supergiants can have component-specific or model-dependent values. Survey panels show photographic sky fields, not the physical surface of the star.