Terzan 5 – Fossil Relic
In this image taken by the Hubble Space Telescope you can see Terzan 5. It is located in the constellation of Sagittarius (The Archer, https://goo.gl/QAysWt), about 19,000 light-years away from Earth.
Research suggests that the star formation (https://goo.gl/Mn2Zxf) in Terzan 5 was not continuous but instead happened in two phases, about 7 billion years apart.
Terzan 5 was believed to be a globular cluster, but because of the age gap and different metallicities (https://goo.gl/2siJh7) of the two star generations it is possible that it is the core of a disrupted dwarf galaxy (https://goo.gl/S4pJVZ), not a true globular cluster. Terzan 5 has many X-ray sources, possibly because of the high stellar density in its core, leading to many star collisions and formation of close binaries.
Terzan 5 was discovered by the French astronomer Agop Terzan (https://goo.gl/0VbYrB) in 1968.
Take a look here at Terzan 1, a globular cluster:
What is a globular cluster?
A globular cluster is a spherical collection of up to millions of stars held together by their own gravitational forces and orbiting a galaxy core as a satellite. They have very high stellar densities at their core. More information here: