Planetary Science

Inner workings of the Sun revealed

Scientists peek into the Sun by estimating magnetic fields using radio observations

October 14, 2021
The Scitech

The Sun is an extremely active object, spewing out vast quantities of gas in many violent events and the corona is a region of very high temperatures, strong magnetic fields, and violent plasma eruptions. A class of such eruptions are Coronal Mass Ejections (CMEs). CMEs are the most powerful explosions happening in our solar system. When a really strong CME blows past the Earth, it can damage the electronics in our satellites and disrupt radio communication networks on Earth. A team of scientists from the Indian Institute of Astrophysics (IIA) along with their collaborators, used data from their radio telescopes to measure the magnetic field and other physical conditions of the plasma in a CME detected on 1 May 2016. It was found with the help of radio telescopes of IIA in Gauribidanur, Karnataka, along with some space-based telescopes that observed the Sun in extreme ultraviolet and white light and was caught when the base of its activity was just behind the visible limb of the Sun. This allowed the researchers to detect a much weaker radio emission called thermal (or blackbody) radiation from the plume of gas that was ejected in the CME. They were also able to measure the polarisation of this emission, which is indicative of the direction in which the electric and magnetic components of the waves oscillate. Using this data, they then calculated the physical properties of the ejected plasma as well. The results of the study have been published in the journal Geophysical Research Letters.

“Though CMEs can occur anywhere on the Sun, it is primarily those which originate from regions near the centre of the visible solar surface (called the photosphere) like the one we studied that are important for us, since they may propagate directly towards the Earth,” said R. Ramesh, the lead author of the paper. “Radio observations of the thermal emission, like in our study, lets us study the CMEs right from the surface itself”, said A. Kumari, a co-author. “Knowing the source region of the CMEs, the associated magnetic field, and their kinematics in the region up to seven lakh kilometer either above the solar surface or off its limb, are important to fully understand the characteristics of the CMEs in a holistic manner,” says C. Kathiravan, another co-author of the study.

Source: PIB