Gamma Leonis — Double Star in Leo
HIP 50583; Gamma2 Leonis; 41 Leonis
About Gamma Leo
Description
Gamma Leonis B (Gamma-2 Leo) is the fainter half of the famous Algieba double star system in Leo. The pair consists of two K-type giants about 130 light-years away — a K1 primary and a G7 secondary — in a 554-year orbit. Gamma-2 contributes magnitude 3.80 to the combined system magnitude of 1.98. The pair's separation is currently about 4.6 arcseconds and widening slowly.
Observing Tips
Gamma Leonis is one of the showpiece double stars of the northern sky. Split the pair with any 3-inch telescope at 100x — both components appear as matching yellow-orange giants. The secondary is about a magnitude fainter than the primary, and the color match makes the scene look like twin suns. Find Algieba on the Lion's mane, partway between Regulus and Adhafera. Best observed February through May.
History
The Algieba name (an Arabic word for "forehead" or "mane") traditionally applies to the combined system; modern catalogs distinguish Gamma-1 (the brighter star, named Algieba by the IAU) from Gamma-2. The binary nature was noted by William Herschel in 1782, and the orbit was first computed in the late 19th century.
Fun Facts
The Algieba system is one of the oldest known binaries with a fully resolved orbit. A planet (Gamma Leo Ab) has been found around the brighter component, orbiting every 1.2 years — making Algieba one of the rare bright binaries known to host planets around its primary giant. The orbit of the two giants is highly eccentric, with their separation ranging from 125 AU at periastron to 336 AU at apastron.
Observe
1Physical Properties
3How easy to split?
| Telescope | Bortle 3 | Bortle 4 | Bortle 5 |
|---|---|---|---|
| 80 mm refractor 80mm refr. | V. hard+ | V. hard+ | V. hard+ |
| 150 mm Newton 150mm Newt. | Hard | Hard | Hard |
| Celestron C8 (203 mm SCT) C8 203mm | Hard+ | Hard+ | Hard+ |
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: 3.8 · B: 9.6 · Sep: 4.8″ · PA: 288° · 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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