What kind of star is Izar?
Izar, catalogued as Epsilon Boötis (ε Boo; name applies to component Aa), appears in the official constellation Boötes. Its apparent visual magnitude is 2.45 combined, while its estimated distance is about 236 light-years. Astronomers classify the object as K0 II–III + A-type companion. 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.
Epsilon Boötis combines an evolved orange K giant with a hotter, fainter A-type companion. They are separated by only a few arcseconds, so atmospheric seeing and diffraction make the system more demanding than its combined magnitude suggests. The SIMBAD parallax places the pair around 236 light-years away. Their contrasting temperatures create the familiar orange-and-blue impression, although perceived colour depends on aperture, magnification, adaptation and simultaneous contrast. The components move together and constitute a physical binary with an orbital period measured in centuries, meaning only part of the orbit has been directly tracked. Izar illustrates stellar evolution within one system: the initially more massive component has already expanded into a giant while its partner remains much closer to the main sequence.
The coordinate pair RA 14h 44m 59.22s, Dec +27° 04′ 27.2″ 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.
Izar data at a glance
| Proper name | Izar | Catalogue designation | Epsilon Boötis (ε Boo; name applies to component Aa) |
|---|---|---|---|
| Constellation | Boötes | Apparent magnitude | 2.45 combined |
| Spectral or system type | K0 II–III + A-type companion | Estimated distance | about 236 light-years |
| Right ascension (J2000) | 14h 44m 59.22s | Declination (J2000) | +27° 04′ 27.2″ |
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 Izar
From Arabic izār, “veil” or “loincloth.” The alternative Pulcherrima—Latin for “most beautiful”—was popularized for the pair's telescopic appearance.
Izar is one of several Boötes names transmitted through Arabic astronomy. Friedrich Georg Wilhelm von Struve called the pair Pulcherrima because of its appearance, and that nickname remains common among double-star observers. The IAU standardized Izar for the primary component, while Epsilon Boötis identifies the combined catalogue system. Nineteenth-century micrometer measurements began the long positional record that allows today's observers to see the slow progress of its orbit.
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 Izar
Arc from the Big Dipper to Arcturus, then move northeast along Boötes. Use 100–200× on a night of steady seeing. A clean split shows a bright amber primary and a much fainter companion often described as bluish.
A northern favourite, highest on spring and early-summer evenings; visible well into southern temperate latitudes. 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
- Best during April through July evenings.
- Allow the telescope to cool and check collimation.
- Start near 100× and increase magnification only if seeing supports it.
- Judge the split, not an expected colour label; colour perception varies.
Interesting facts about Izar
- Izar is nicknamed Pulcherrima, the most beautiful.
- Its components have strongly contrasting temperatures.
- The physical orbit takes many centuries.
- The brighter component is an evolved giant.
- It is a classic test double for small telescopes.
Continue from Izar into the night sky
Use the Boötes 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.