Indian Scientists Discover Helium-Enhanced Cool Bright Stars Among Metal-Rich Parts Of Omega Centauri Globular Cluster

In a 'stellar' discovery, Indian scientists have discovered Helium-enhanced cool bright stars among the metal-rich sample of Omega Centauri globular cluster.

A team of scientists from the Indian Institute of Astrophysics (IIA), an autonomous institute under the Department of Science & Technology (DST), studied numerous stars of the Omega Centauri and discovered Helium-enhanced cool bright stars among the metal-rich sample of the globular cluster, the Ministry of Science and Technology said in a release.

Globular clusters are the stellar systems with millions of stars formed from the same gaseous cloud. Hence, usually, the stars formed will be homogeneous in their chemical composition of elemental abundances. But, there are clusters which deviate from this norm. One of them is Omega Centauri, the brightest and the largest globular cluster in our Milky Way galaxy, the ministry said.

The different stars of Omega Centauri do not show the same metal content, a parameter that indicates its age, but a large range in it.

Due to the anomalous elemental abundances, the formation scenario may be different from normal. Normally, the abundances are derived using the assumption that Helium (He) is one-tenth of the Hydrogen-abundance, it said.

The study by the IIA scientists, a result of the spectroscopic survey conducted of this cluster, determines the He-abundance of these stars for the first time and has been published in ‘The Astrophysical Journal’.

According to the ministry, this is the first-ever spectroscopic determination of He-abundance in Omega Centauri.

The study provides a very important clue for the origin of the He-enhanced population establishing that these are the second generation of stars formed from the metal-rich and He-enhanced material from the first generation of stars. And, also that the He-enhanced main-sequence stars evolve to the metal-rich He-enhanced cool bright stars as our program starts, it said.

While in most stars, Hydrogen is the most abundant element, if the abundance of Hydrogen is reduced, correspondingly, the Helium abundance increases because the sum of Hydrogen and Helium is a constant, and the other heavier elements are in traces.