International Space Agencies – Missions and Discoveries

Radio lights from Sun’s Corona

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Murchison Widefield Array (MWA), Nanoflares

Mains level : Coronal heating of Sun

A group of India scientists have recently discovered tiny flashes of radio light emanating from all over the Sun, which they say could help in explaining the long-pending coronal heating problem.

Possible prelim question:

The Murchison Widefield Array (MWA) Telescope recently seen in news is a landmark in observing: Gravitational Waves/Black Holes/Sun’s Corona/ etc..

What is Sun’s Corona?

  • The corona is the outermost part of the Sun’s atmosphere. It is the aura of plasma that surrounds the Sun and other stars.
  • The Sun’s corona extends millions of kilometres into outer space and is most easily seen during a total solar eclipse, but it is also observable with a coronagraph.
  • Spectroscopy measurements indicate strong ionization in the corona and a plasma temperature in excess of 1000000 Kelvin much hotter than the surface of the Sun.

Radio lights observed

  • These radio lights or signals result from beams of electrons accelerated in the aftermath of a magnetic explosion on the Sun.
  • While the magnetic explosions are not yet observable, these weak radio flashes are ‘smoking guns’ or the evidence for the same.
  • Hence it brought the researchers closer to explaining the coronal heating problem.

Their significance

  • These observations are the strongest evidence till date that the tiny magnetic explosions originally referred to as ‘nanoflares’ by eminent American solar astrophysicist Eugene Parker.
  • It is the possible phenomena that could be heating up the corona (the aura of plasma that surrounds the sun and other stars).

The Murchison Widefield Array (MWA)

  • The phenomenon of coronal heating has been known for the last 70 years, the availability of cutting edge data from the Murchison Widefield Array (MWA) radio telescope proved to be a game-changer.
  • The MWA is a low-frequency radio telescope, located at the Murchison Radio-astronomy Observatory (MRO) in Western Australia.
  • The MWA has been developed by an international collaboration, including partners from Australia, New Zealand, Japan, China, India, Canada and the United States.

Solving the mystery

  • The strength of the magnetic fields varies a lot from one place on the surface of the Sun to another, by more than a factor of 1,000.
  • But the corona is hot everywhere. So, this heating process has to work all over the corona, even in regions of weak magnetic fields.
  • Until now, the process of how this magnetic energy is deposited in the corona had remained a mystery.
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