Jewel Box
NGC 4755
Properties
Position & Identifiers
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Jewel Box · 7.8′ diameter · N up, E left
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About Jewel Box
Description
The Jewel Box (NGC 4755) is a brilliant open cluster in Crux, about 6,440 light-years away. Named by John Herschel, who compared it to a piece of fancy jewelry with its striking array of blue, white, and red supergiants clustered within 10 arcminutes. It is visible to the naked eye at magnitude 4.2.
Observing Tips
One of the most beautiful open clusters in the sky. A telescope at 50-100x reveals the famous color contrasts — the red supergiant Kappa Crucis stands out against brilliant blue-white companions. Binoculars show a bright, condensed group near Beta Crucis. Best from southern latitudes in autumn and winter.
History
Discovered by Nicolas Louis de Lacaille in 1751. John Herschel named it the Jewel Box during his southern sky survey, describing it as "a casket of variously coloured precious stones."
Fun Facts
The Jewel Box is only about 14 million years old. The bright red supergiant Kappa Crucis (DU Crucis) has already evolved off the main sequence despite the cluster's youth, indicating it is one of the most massive stars in the cluster at about 20 solar masses.