Izar
HIP 72105; Epsilon Boo; 36 Boo
Sep: 2.8", Companion: mag 4.8
Physical Properties
Position & Identifiers
Visibility
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Multiple Star System
Eyepiece View
Sep: 2.8″ · PA: 347° · N up, E left
At limit · Rayleigh: 2.3″ · Dawes: 1.9″ · Eff: 3.1″
Size Comparison
Stellar Lifecycle
Spectral Classification
Hertzsprung-Russell Diagram
Blackbody Spectrum
Stellar Absorption Spectrum
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Stellar Notes
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About Izar
Description
Izar (also called Pulcherrima) is one of the most beautiful double stars in the sky at magnitude 2.70 in Bootes. A telescope reveals a stunning pair — a golden-orange giant (K0II-III, mag 2.5) and a blue-white companion (A2V, mag 4.6) separated by about 2.9 arcseconds. Located about 203 light-years from Earth.
Observing Tips
Izar lies in the waist of Bootes, about 10 degrees northeast of Arcturus. Resolving the close pair requires a 4-inch or larger telescope at 150x or more. The color contrast — warm orange and cool blue — is exquisite. Best observed April through August when Bootes is well-placed.
History
The name Izar comes from the Arabic 'al-izar,' meaning 'the girdle' or 'veil.' The celebrated astronomer Friedrich Georg Wilhelm Struve gave it the Latin name Pulcherrima, meaning 'the most beautiful,' after resolving the pair and being struck by its color contrast.
Fun Facts
Struve's nickname 'Pulcherrima' (most beautiful) has stuck for nearly 200 years, and Izar regularly appears on lists of the finest double stars. Its tight separation makes it a good test of telescope optics and atmospheric seeing.