Scientists make 1st direct observation of magnetic explosion on Sun

A team of international scientists led by Indian Institute of Technology-Benaras Hindu University (IIT-BHU) have made the first direct observation of a new kind of magnetic explosion on the Sun’s uppermost atmospheric layer through Nasa’s Solar Dynamics Observatory (SDO).

Through the Atmospheric Imaging Assembly (AIA) for SDO that provides multi-wavelength images of the sun’s corona, the 10-member team saw this magnetic explosion via a phenomenon called controlled or forced reconnection – a theory hypothesised 15 years ago by physicists – for the first time in the solar corona — the Sun’s uppermost atmospheric layer.

Researchers said understanding forced reconnection may help scientists better predict space weather – bursts of solar radiation that can damage satellites – when disruptive high-energy charged particles might come speeding at Earth. Many modern day technologies including telecommunication, GPS navigation satellites, electric power grids, air-traffic on polar routes are dependent on space-reliant technologies and satellite operations are affected and impacted by solar storms. The new evidence, published in the Astrophysical Journal of the American Astronomical Society on December 18, will also help understand a key mystery about the Sun’s atmosphere, and may also lead to breakthroughs in the controlled fusion and experiments at laboratory scales where plasma is highly diffusive and very hard to control.

Essentially, all transient events in the Sun’s corona such as solar flares or coronal jets are believed to occur through a process called spontaneous magnetic reconnection which is reorganisation of magnetic fields. The process releases large amounts of stored energy and high energy particles get released and travel through the interplanetary space (can also affect our satellites).

What’s new is that the never-seen-before magnetic explosion captured by SDO was not a result of spontaneous magnetic reconnection but was ‘forced’ driven by external disturbances in the solar corona thereby making it the first direct observation.

“Forced reconnection in this case was caused by prominence (a large loop of cold material launched by an eruption on the solar surface) that was suspended along the magnetic field line in the solar atmosphere,” said AK Srivastava, lead investigator and solar scientist at the Indian Institute of Technology-Benaras Hindu University (IIT-BHU).

When the cold cloud of plasma blob – prominence – in the corona started falling back to the Sun’s surface after its eruption, the prominence ran into a snarl of magnetic field lines, sparking a magnetic explosion which triggered a distinct X-shape forced reconnection that released large amounts of energy.

Dipankar Banerjee, co-author and director, Aryabhatta Research Institute of Observational Sciences, Nainital, said a reconnection process is normally associated with the Sun’s active regions that possess strong magnetic field concentrations. Other solar eruptions like flares and coronal mass ejections could also cause forced reconnection.

“Large numbers of sunspots constitute an active region which is known to generate reconnection and solar flares. For the first time, we have evidence that even a prominence eruption which is not linked to the Sun’s active region can result in forced reconnection and release a lot of energy,” said Banerjee. “We will continue to look for more forced reconnection events.”