Algieba — Double Star in Leo
HIP 50583; Gamma1 Leonis; 41 Leonis
About Algieba
Description
Algieba is one of the finest double stars in the sky at magnitude 2.61 in Leo. A small telescope reveals a stunning pair — a golden-orange giant (K1III, mag 2.3) and a slightly fainter yellow-green companion (G7III, mag 3.5) separated by about 4.5 arcseconds. Located about 126 light-years from Earth, the primary has a confirmed exoplanet.
Observing Tips
Algieba lies in the Sickle of Leo, the curved line of stars forming the Lion's head. In a telescope at 100x or more, it splits into a gorgeous warm-toned double — golden orange and yellowish green. It rivals Almach and Albireo as one of the most beautiful double stars. Best observed February through June.
History
The name Algieba comes from the Arabic 'al-jabhah,' meaning 'the forehead.' The double star nature was first observed in 1782 by William Herschel. In 2009, a giant exoplanet (Gamma Leo b) with about 8.8 Jupiter masses was discovered orbiting the primary.
Fun Facts
Algieba's color contrast — deep gold and pale green — makes it one of the most beautiful doubles in the northern sky. The 'green' star is likely an optical illusion enhanced by contrast with the orange primary, as truly green stars do not exist.
Observe
1Physical Properties
3How easy to split?
| Telescope | Bortle 3 | Bortle 4 | Bortle 5 |
|---|---|---|---|
| 80 mm refractor 80mm refr. | Easy | Easy | Easy |
| 150 mm Newton 150mm Newt. | Easy | Easy | Easy |
| Celestron C8 (203 mm SCT) C8 203mm | Easy | Easy | Easy |
Bortle 3 = rural · 4 = outer suburbs · 5 = suburbs
4Visibility
Set a location in User Settings to see visibility data.
5Multiple Star System Quadruple C,D: optical
Separation over time
Apparent separation over time, computed from ORB6 orbital elements. Steep curves indicate fast-changing pairs — catch them while they're splittable.
Eyepiece View
A: 2.6 · B: 3.6 · Sep: 4.8″ · PA: 127° · N up, E right
Resolved · Rayleigh: 2.3″ · Dawes: 1.9″ · Eff: 2.3″
Explore
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Size Comparison
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Compare Stars
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Spectral Classification
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Hertzsprung-Russell Diagram
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Stellar Lifecycle
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Blackbody Spectrum
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Stellar Absorption Spectrum
Simulated absorption spectrum based on spectral type. Hover over lines to identify elements.
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Stellar Fusion
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Exoplanets
1 known planet
View in 3D
| Planet | Radius | Mass | Period | Distance |
|---|---|---|---|---|
| gam1 Leo b | 12.50R⊕ | 8.78M♃ | 1.2yr | 130ly |
Habitable Zone
Size & Mass Comparison
About exoplanets — how we find them and which host stars you can observe
Discover
16Stellar Notes
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Light Travel Time Machine
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Relativistic Travel
Nearby in the Sky
Other targets within a few degrees — pan your scope a little and keep exploring.
Visibility scores assume a 150 mm Newton at Bortle 4.
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