Jewel Box (star cluster)

The Jewel Box, Kappa Crucis Cluster, NGC 4755, is an open cluster in the constellation Crux, originally discovered by Nicolas Louis de Lacaille during 1751–1752. This famous cluster was later named the Jewel Box by Sir John Herschel when he described its telescopic appearance as "...a superb piece of fancy jewellery" It is easily visible to the naked eye as a hazy star some 1.0° southeast of the first-magnitude star Beta Crucis. This hazy star was given the Bayer star designation Kappa Crucis, from which the cluster takes one of its common names. The modern designation Kappa Crucis has been assigned to one of the stars in the base of the A-shaped asterism of the cluster, the third brightest cluster star (HD 111973, HIP 62931, HR 4890), located at the base of the right leg of the A. This is a blue supergiant of spectral type B3Iae, shining at the apparent photometric visual magnitude of 5.94V. Two other cluster stars are brighter than κ Cru, namely, 5.77 magnitude star HD 111904 (HIP 62894), at the tip of the A, and HD 111613 (HIP 62732) at 5.75, which is 15 arc minutes beyond the asterism toward Beta Crucis.