Terzan 1: Hubble Spots Globular Cluster
The Wide Field Planetary Camera 2 on the NASA/ESA Hubble Space Telescope has captured a luminous image of the globular cluster Terzan 1, which is approximately 20,000 light-years away from the Earth. This globular cluster is found in the constellation Scorpius (the scorpion), which is one of the 150 globular clusters in the Milky Way.
Globular clusters are typically comprised of about 100,000 stars, which are held together by their mutual gravitational attraction that is spherically shaped a few hundred light-years across. Most galaxies have numerous globular clusters. The Milky Way, for instance, contains a few hundred globular clusters, compared to giant elliptical galaxies, which contain several thousand globular clusters, according to NASA.
Some of a galaxy's oldest stars are found in globular clusters. The reddish colored stars and the bright blue stars in the image are foreground stars, which are not part of the cluster. The age of these stars in the globular cluster shows that these stars were formed in the early stages of galaxy formation and they also enable researchers to have a better understanding of how galaxies formed.
Similarly to many other globular clusters, Terzan 1 is a source of X-rays. These X-rays are most likely derived from binary star systems, which contain a dense neutron star and a normal star. The neutron star extracts material from its companion star, which causes a burst of X-ray emission. The system then goes into a quiescent phase where the neutron star cools, this gives off X-ray emission with varying features, before enough material from the companion builds up to trigger another outburst.
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