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Blue Straggler stars

  • Published
    26th Apr, 2022

Indian Institute of Astrophysics, Bengaluru, researchers have found support for one way to understand the aberrant behaviour of Blue Straggler stars.

For this, the researchers also made use of the observations by the UVIT instrument (UltraViolet Imaging Telescope) of ASTROSAT, India’s first science observatory in space.


About Blue stragglers Stars:

  • Blue stragglers, a class of stars on open or globular clusters that stand out as they are bigger and bluer than the rest of the stars; have intrigued scientists who have for long probed their origin.
  • Carrying out the first-ever comprehensive analysis of blue stragglers, Indian researchers found that half of the blue stragglers in their sample are formed through mass transfer from a close binary companion star, one third are likely formed through collisions of 2 stars, and the remaining are formed through interactions of more than 2 stars.
  • A bunch of stars born at the same time from the same cloud form a star cluster.
  • As time passes, each star evolves differently depending on its mass.
  • The most massive and bright stars evolve and move off the main sequence creating a bend in their track, known as the turnoff.
  • Stars above this bend or brighter and hotter stars are not expected in a cluster, as they leave the main sequence to become red giants.
  • But in 1953, Allan Sandage found that some stars seem to be hotter than the turnoff of the parent cluster.
    • Initially, these blue stars still straggling above the turnoff were not part of these clusters.
    • However, later studies confirmed that these stars are indeed cluster members, and they were termed “Blue Stragglers”.
  • The only probable way these stars can still be present in these clusters is if they have somehow acquired extra mass along the way while on the main sequence.
  • Confirming the mechanisms of the mass gain required a study using a large sample of blue-straggler stars and estimates of the mass they have gained.

Indian Institute of Astrophysics

  • The Indian Institute of Astrophysics is a premier institute devoted to research in astronomy, astrophysics and related physics.
  • It traces its origins back to an observatory set up in 1786 at Madras which from the year 1792 began to formally function at its Nungambakkam premises as the Madras Observatory. In 1899, the observatory moved to Kodaikanal.
  • In the year 1971, the Kodaikanal Observatory became an autonomous society, the Indian Institute of Astrophysics.
  • The headquarters were shifted to Bengaluru into its present campus in Koramangala in 1975.
  • Today, funded by the Department of Science and Technology, the Institute ranks as a premier institution devoted to research and education of astronomy and physics in the country.
  • The main observing facilities of the Institute are located at Kodaikanal, Kavalur, Gauribidanur and Hanle.
  • The Kodaikanal Observatory has for over a century been the principal centre of activity in observational solar and atmospheric physics.
  • The Vainu Bappu Observatory at Kavalur has been the main optical observatory of the Institute for nighttime astronomy since the late 1960s. 
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