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Very Large Telescope

Topics Covered: Awareness in space.

Very Large Telescope

What to study?

For Prelims and Mains: About VLT and it’s features, what is Betelgeuse? Significance of the findings, about Orion.

Context: Using the European Space Organisation’s (ESO) Very Large Telescope (VLT), astronomers have noticed the unprecedented dimming of Betelgeuse, a red supergiant star (over 20 times bigger than the Sun) in the constellation OrionAlong with the dimming, the star’s shape has been changing as well, as per recent photographs of the star taken using the VISIR instrument on the VLT.


What is happening to Betelgeuse and why is it significant?

Betelgeuse was born as a supermassive star millions of years ago and has been “dramatically” and “mysteriously” dimming for the last six months. According to a report in Sky and Telescope, among the brightest night time stars, Betelgeuse ranks 10th, but by the last week of December 2019, its brightness had dimmed so low, that the star was ranked as the 21st brightest, “a remarkable decline — and a historic low.”

  • Astronomers do not think that Betelgeuse is dimming because it is going to explode. They have other hypotheses that may explain the reasons for Betelgeuse’s change in shape and dimming. The two scenarios they are working on are a cooling of the surface due to exceptional stellar activity or dust ejection towards earth.

About VLT:

It is the world’s most advanced optical instrument, consisting of four Unit Telescopes with main mirrors of 8.2m diameter and four movable 1.8m diameter Auxiliary Telescopes.

  • The telescopes can work together, to form a giant ‘interferometer’, the ESO Very Large Telescope Interferometer, allowing astronomers to see details up to 25 times finer than with the individual telescopes.
  • Location: Atacama Desert, Northern Chile.
  • The VLT consists of four individual telescopes. They are generally used separately but can be used together to achieve very high angular resolution.
  • The four separate optical telescopes are known as Antu, Kueyen, Melipal, and Yepun, which are all words for astronomical objects in the Mapuche language. 

How it works? Significance:

The light beams are combined in the VLTI using a complex system of mirrors in underground tunnels where the light paths must be kept equal to distances less than 1/1000 mm over a hundred metres.

  • With this kind of precision the VLTI can reconstruct images with an angular resolution of milliarcseconds, equivalent to distinguishing the two headlights of a car at the distance of the Moon.
  • Individual telescope help see objects that are four billion (four thousand million) times fainter than what can be seen with the unaided eye.

Sources: Indian Express.