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Current Affairs

Global magnetic field of Sun’s atmosphere measured for first time

Date: 09 August 2020 Tags: Space

Issue

An international team of solar physicists has measured the global magnetic field of the Sun’s corona, or outer atmosphere, for the very first time. 

 

Background

The Sun is our closest star and we have been studying it for a long time. Yet, it has many associated puzzles that are unexplained. 

 

Details

  • There are two main puzzles about the Sun which this advancement will help address. First is the coronal heating problem.

  • Though the core of the Sun is at a temperature of about 15 million degrees, its outer layer, the photosphere is a mere 5700 degrees hot.

  • However, its corona or outer atmosphere, which stretches up to several million kilometres beyond its surface, is much, much hotter than the surface. It is at a temperature of one million degrees or more.

  • That is the question which has baffled solar physicists. Popular attempts to explain this puzzle invoke the magnetic field of the corona. 

  • The other set of questions pertain to the mechanisms of eruptions of the Sun, such as solar flares and coronal mass ejections. These are driven by magnetic reconnections happening in the Sun’s corona.

  • The team used a technique known as coronal seismology or magneto seismology to measure the coronal magnetic field which has been known for a few decades. 

  • The waves that propagate through a magnetic plasma are called magnetohydrodynamic (MHD) waves.

  • There are different types of MHD waves, and one of these is the transverse MHD wave. From the theoretical calculation, it can be shown that the properties of the transverse MHD wave are directly related to the strength of magnetic fields and the density of the corona.