What kind of star is Zubenelgenubi?
Zubenelgenubi, catalogued as Alpha² Librae (α² Lib; named component Aa), appears in the official constellation Libra. Its apparent visual magnitude is 2.75 for α²; about 2.6 combined, while its estimated distance is about 76 light-years. Astronomers classify the object as A-type multiple system. 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.
Alpha Librae is a multiple system dominated by α² Librae and the wider α¹ companion. The pair is separated by several arcminutes, wide enough for sharp eyes under good conditions and effortless in binoculars. Gaia-era astrometry confirms compatible distance and motion, while each principal point has additional multiplicity reported at closer scales. SIMBAD's parallax for α² corresponds to roughly 76 light-years. The brightest component is an A-type star with a chemically unusual spectrum, while other members are cooler. Zubenelgenubi lies close to the ecliptic, making lunar and planetary passages common. The nearby-looking star KU Librae shares broadly similar motion and may belong to an even wider co-moving arrangement, although definitions of such fragile systems require care.
The coordinate pair RA 14h 50m 52.71s, Dec −16° 02′ 30.4″ 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.
Zubenelgenubi data at a glance
| Proper name | Zubenelgenubi | Catalogue designation | Alpha² Librae (α² Lib; named component Aa) |
|---|---|---|---|
| Constellation | Libra | Apparent magnitude | 2.75 for α²; about 2.6 combined |
| Spectral or system type | A-type multiple system | Estimated distance | about 76 light-years |
| Right ascension (J2000) | 14h 50m 52.71s | Declination (J2000) | −16° 02′ 30.4″ |
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 Zubenelgenubi
From Arabic al-zubānā al-janūbiyy, “the southern claw.” The name predates Libra's modern scale-pan interpretation and preserves the stars' older placement in Scorpius's claws.
Libra's stars once represented the Scorpion's claws, which explains why both principal Libra names begin with Arabic zubānā, “claws.” Greek and Roman traditions increasingly treated this region as a balance, and modern constellations preserve Libra separately. The IAU assigns Zubenelgenubi specifically to α² Librae Aa rather than to the whole visible pair. Its unusually long transliterated form has many published variants, but standardized spelling makes modern database searches and cross-identification more reliable.
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 Zubenelgenubi
Find Libra between Spica and Antares. Zubenelgenubi is the southern of Libra's two brightest stars. Try first with unaided eyes, then use binoculars to separate α¹ and α² cleanly in the same field.
Visible from most inhabited latitudes, highest on northern late-spring and southern autumn evenings. 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 May through July evenings.
- Attempt the wide split without optics from a dark site.
- Binoculars make the two principal points obvious.
- Watch lunar conjunctions because the system lies near the ecliptic.
Interesting facts about Zubenelgenubi
- Its name means the southern claw.
- The principal pair can be resolved with binoculars and sometimes unaided eyes.
- The system contains more than the two obvious stars.
- It lies close to the ecliptic.
- Its name records Libra's historical connection with Scorpius.
Continue from Zubenelgenubi into the night sky
Use the Libra 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.