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NGC 2808: New population of ultraviolet stars discovered

Date: 13 March 2019 Tags: Space

Astronomers from Thiruvananthapuram and Mumbai have identified new population of ultraviolet stars in the globular cluster NGC 2808. These starts were identified using Indian multi-wavelength space observatory AstroSat.

Globular clusters

  • They are collections of thousands to millions of stars, moving as one unit.
  • These stars are believed to have formed together at roughly the same time and are tightly held together by gravity of cluster itself.
  • Some globular clusters could be among the oldest objects in our Milky Way, which hosts over 150 of them.
  • It contains stars of different masses but with similar chemical composition. Its detail could reveal evolution of stars of different masses at different stages.

NGC 2808

  • It is one of the most massive globular clusters know to humans. It is located at a distance of 47,000 light years from Earth.
  • It was observed for first time by the team of researchers using UltraViolet Imaging Telescope (UVIT) on-board AstroSat.
  • So far AstroSat has taken images of over 2,000 individual stars in NGC 2808 through various ultraviolet filters.

Significance

NGC2808 is special as optical observations have shown that it may have at least five different populations of stars.  It is contrary to normal assumption that all stars in such clusters are of the same age.

ASTROSAT

  • It is India’s first dedicated multi wavelength space observatory. It was launched in September 2015. It orbits in low earth equatorial orbit at altitude of 650 km.
  • It has mission life of 5 years. It observes universe in the optical, Ultraviolet (UV), low and high energy X-ray regions of the electromagnetic spectrum.
  • It is unique as compared to most other scientific satellites which are only capable of observing a narrow range of wavelength band.
  • It operationalisation is one of the major scientific missions of ISRO. India is among few nations like US, Japan, Russia and Europe to have its own space observatory.