From Wired Science:
This stunning image of the Kappis Crucis Cluster, nicknamed the “Jewel Box,” was one of the last gifts from a retiring camera on the Hubble Space Telescope.
Just before NASA brought the Wide Field Planetary Camera 2 back to Earth in mid-2009, it snapped this photo of the core of the NGC 4755 star cluster, the first comprehensive image of an open galactic cluster taken in multiple wavelengths. Using seven different filters, Hubble captured the Jewel Box cluster in far ultraviolet to near-infrared light. The different colors of the stars — from pale blue to bright ruby red — result from their differing intensities at various ultraviolet wavelengths.
Just bright enough to be seen from Earth with the naked eye, the Jewel Box was given its name by English astronomer John Herschel in the 1830’s, who thought the sparkling blue and red stars resembled expensive jewelry. Like most open star clusters, the Jewel Box is made up of an array of sister stars, all formed from the same cloud of gas and dust with similar ages and chemical make-up. Located about 6,400 light-years away, near the Southern Cross in the constellation of Crux, the Jewel Box contains roughly 100 stars.
Besides Hubble, two other telescopes have also recently captured new images of the Jewel Box. A wide-field photo taken by the 2.2-meter telescope at the European Southern Observatory’s La Silla observatory in Chile shows the multi-colored cluster surrounded by thousands of neighboring stars. A close-up from ESO’s Very Large Telescope captures the stars in detail and ranks as one of the best images of the Jewel Box ever taken from the ground. Both images can be seen in the composite photo below.
Image 1: NASA/ESA and Jesús Maíz Apellániz/Instituto de Astrofísica de Andalucía, Spain. Image 2: ESO, NASA/ESA, Digitized Sky Survey 2 and Jesús Maíz Apellániz/Instituto de Astrofísica de Andalucía, Spain.