Globular Star Cluster NGC 6397 in Ara | MPG/ESO Telescope
The globular cluster NGC 6397, located at a distance of approximately 7,800 light-years in the southern constellation Ara within the Milky Way galaxy. It has undergone a "core collapse" and the central area is very dense. It contains about 400,000 stars and its age (based on evolutionary models) is 13,400 ± 800 million years.
NGC 6397 (also known as Caldwell 86), resembles a treasure chest of glittering jewels. Here, the stars are jam-packed together. The stellar density is about a million times greater than in our Sun's stellar neighborhood. The stars are only a few light-weeks apart, while the nearest star to our Sun is over four light-years away. NGC 6397 was discovered by French astronomer Nicolas-Louis de Lacaille in 1752.
This ancient stellar jewelry box glitters with the light from hundreds of thousands of stars. The cluster’s blue stars are near the end of their lives. These stars have used up their hydrogen fuel that makes them shine. Now they are converting helium to energy in their cores. This fuses at a higher temperature and appears blue. The reddish glow is from red giant stars that have consumed their hydrogen fuel and have expanded in size. The myriad small white objects include stars like our Sun.
The photo is a composite of exposures in the B-, V- and I-bands obtained in the frame of the Pilot Stellar Survey with the Wide-Field-Imager (WFI) camera at the 2.2-m ESO/MPG telescope at the European Southern Observatory's La Silla Observatory. It was prepared and provided by the ESO Imaging Survey team. The spikes seen at some of the brighter stars are caused by the effect of overexposure (CCD "bleeding").
Credit: European Southern Observatory (ESO)
Release Date: Aug. 17, 2004
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