Hubble investigates the globular star cluster NGC 2419.

The image from the NASA/ESA Hubble Space Telescope of the globular star cluster NGC 2419 captures its beauty and fascination. A globular cluster is a spherical group of stars that orbits the center of a galaxy, and in this case, it is our very own Milky Way. This star cluster lies at a distance of around 300,000 light-years from our solar system in the constellation Lynx. This stunning celestial phenomenon showcases the grandeur of our galaxy and its magnificent star clusters that are both captivating and awe-inspiring.

Globular clusters are known for their population of stars which are remarkably similar,This is because they formed at roughly the same time and so, astronomers can use their chemical composition, known as metallicity, to determine their relative age. As such, they tend to share similar characteristics, including their stellar helium content. Astronomers therefore believed that all the stars in a globular cluster would contain similar amounts of helium. This is one of the ways astronomers are able to determine the age and composition of these stars in this cluster, allowing to better understand how these stars formed and evolved over time.

Hubble’s observations of NGC 2419 shattered the idea that all stars within a globular cluster have the same chemical composition. This globular cluster holds two separate populations of red giant stars, one of which is unusually helium-rich. In addition, their nitrogen content varies significantly. What is even more interesting is that the helium-rich stars are predominantly in the center of the globular cluster and are rotating. These observations raise questions about the formation of globular clusters. Is it possible that these two drastically different groups of stars formed together,Or did this globular cluster come into being by a different route entirely?