Thursday, January 13, 2022

A globular cluster lost in the immensity of space

It is known as the Intergalactic Wanderer and it is not difficult to understand why: the globular cluster photographed in this image (NGC 2419) is in fact located 300,000 light years away from Earth!

By comparison, on average, globular clusters are located twenty thousand light-years away from the galactic center, while the Large Magellanic Cloud, the largest satellite galaxy of the Milky Way, is 160,000 light-years away.

Despite its high distance, NGC 2419 is considered part of our galaxy, since it orbits it in a time of about 3 billion years. Furthermore, NGC 2419 is also one of the largest and brightest clusters in the Milky Way: it has an absolute magnitude of -10 and a mass 900 thousand times that of the Sun!

The mystery, however, concerns the origin of the cluster: it is still not clear how this object was able to form on its current orbit or, if it had formed elsewhere, what mechanism led it to the position where it is today. Furthermore, a recent study has shown that NGC 2419 is composed of stars from two different populations, one richer in helium and one poorer. This has only deepened the mystery, since usually a cluster would have to consist of stars from a single population.

Credit: Adam Block.

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