‘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.


  • 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. 


  • 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).

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