‘Omega Centauri globular cluster’

Category
Science & Technology
Published
2nd Sep, 2020

Scientists at Indian Institute of Astrophysics (IIA) discovered He-enhanced cool bright stars among the metal-rich parts of Omega Centauri globular cluster.

Context

Scientists at Indian Institute of Astrophysics (IIA) discovered He-enhanced cool bright stars among the metal-rich parts of Omega Centauri globular cluster.

About

Omega Centauri, the largest and brightest of all globular star clusters, is a globe-shaped stellar city, teeming with millions of stars. It is estimated to contain several million stars; several hundred variables have been observed in it.
- Globular clusters are large, symmetrically shaped groupings of stars, fairly evenly distributed around the core of our Milky Way galaxy.
- The globular clusters are stellar systems consisting of millions of stars that are formed from a gaseous cloud.
Location: It is located in the southern constellation Centaurus.
Mass: Having a mass of 5 million suns, Omega Centauri is 10 times more massive than a typical globular cluster.
Diameter: Omega Centauri has a diameter of 230 light-years.
Magnitude: It has a magnitudeof 3.7 and is visible to the unaided eye as a faint luminous patch. Omega Centauri is about 16,000 light-years from Earth and is thus one of the nearer globular clusters.

The ‘H’ Element

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

Key-findings

This is the first time He abundance has been found in Omega Centauri and the work has been published in ‘The Astrophysical Journal’.
The different stars of Omega Centauri are not made of the same metal content which is also an indicator of its age.
With the anomalous elemental abundances, the formation of these are at times different from normal.
To be sure, the abundances are made on the back of an assumption that “He is one-tenth of the H-abundance.”

The method

Scientists studied the spectrum by using a low-resolution spectra which had been obtained from the Optometric Medium Resolution Spectrograph (OMRS) installed with the Vainu Bappu Telescope, Vainu Bappu Observatory, Kavalur, India.
They identified the mild Helium and Helium enhanced stars.
Moreover, in order to measure the amount of He that is present in the identified bright/ cool stars of Omega Centauri, the scientists used a high-resolution spectra that has been obtained from the Southern African Large Telescope (SALT).