Discovery of new magnetic explosion on the Sun

The Sun is the source of light and life on our planet. Solar magnetic field makes the Sun dynamic and moody. Our planet also has a magnetic field which results in the Sun-Earth connection. We cannot survive if the Earth were non-magnetic. The study of the Sun’s magnetic field and its connection with the Earth is a problem of universal importance.

Magnetic reconnection is a process by which magnetic lines of force break and rejoin into a lower-energy configuration. This is considered to be the fundamental process by which magnetic energy is converted into plasma kinetic energy. The Sun has a large reservoir of magnetic energy. Magnetic reconnection provides a means of converting some or all of this energy to plasma kinetic and thermal energy.

Magnetic reconnection transcends the traditional disciplines of laboratory and cosmic plasma physics. This process is known to occur in fusion devices such as tokamaks where it causes major disruption of the plasma confinement.

It is thought to occur in solar flares and in other energetic events on the Sun. It takes place at planetary magnetopauses, and in planetary as well as cometary magnetic tails. Reconnection also plays an important role in other cosmic objects such as accretion discs, and many in a variety of current sheets occurring in interplanetary, interstellar, and intergalactic space.

Study of reconnection processes in the laboratory plasmas, in computer simulations, and in the Earth’s magnetosphere is at the forefront of current researches.

In cosmic plasmas, large scale lengths, large scale velocities, and small electrical resistivities combine to form large values of the magnetic Reynolds number, a condition in which the plasma and magnetic fields are tightly coupled or ‘frozen’ together.

If the ratio of plasma to magnetic energy density is large, non-uniform motions in such plasmas often stretch magnetic loops or push differently magnetized regions together into configurations, where magnetic field exhibits large shear. That means it changes direction and magnitude rapidly across a narrow electric current sheet. If the ratio is small, the magnetic field organizes the plasma motion instead.

And the currents have a tendency to flow along magnetic field lines, a situation that also leads to sheared magnetic fields.Using multi-wavelength observations of the solar corona from the NASA Solar Dynamics Observatory (SDO), scientists from IITBHU have directly established the forced reconnection in the Sun’s magnetized plasma. The event is triggered at the higher rates in the corona when two oppositely directed magnetic field lines are perturbed by an external disturbance.

This type of reconnection has never been directly observed in the Sun’s largescale corona.

This seminal finding is published in the leading Astrophysical Journal on 20 December 2019 issue.

These first observational clues to the forced reconnection can be extended to the laboratory plasma.

Understanding of how magnetic reconnection can be forced in a controlled way may help plasma physicists to reproduce reconnection in the laboratory.

This discovery will open up a new window in our understanding the role of the forced reconnection in natural and laboratory plasmas.

It will also constrain the theoretical mechanisms and computer modelling of magnetic reconnection processes.

THIS SEMINAL FINDING IS PUBLISHED IN THE LEADING ASTROPHYSICAL JOURNAL ON 20 DECEMBER 2019 ISSUE.