The Jewel Box cluster, NGC 4755

This famous group of young bright stars is an open cluster stars some 7800 light years from the Sun. It was named the Jewel Box from its description by Sir John Herschel as 'a casket of variously coloured precious stones', which refers to its appearance in the telescope. The bright orange star is kappa Crucis, and it contrasts strongly against its predominantly blue, hot companions. Kappa Cru is a very large, (hence very luminous) quite young star in its red supergiant stage, which paradoxically indicates that its life is drawing to a close. The cluster is looks like a star to the unaided eye and appears close to the eastern-most star of the Southern Cross, so is only visible from southern latitudes.

Entry from NGC 2000.0 (R.W. Sinnott, Ed.) © Sky Publishing Corporation, 1988:

NGC 4755  OC 12 53.6  -60 20 s  Cru  10.    4.2  Cl, vL, st vB (kappa Cru)