More Earth-ward bound solar flares likely in coming days, warn solar physicists

On Wednesday, an intense solar flare (X2 class) hit Earth and affected India and large parts of Southeast Asia. The flare event was recorded between 9 am and 10.30 am. It was the sunspot number AR12992 which led to Wednesday’s solar flare, whose peak state lasted for about 30 minutes recorded at 9.27 IST, reaching an intensity of 2.2 x 10^-4 Watts / m^2.

Solar flares are massive bursts of electromagnetic radiation emerging from the Sun’s surface. They are usually associated with the Sun’s active regions, like sunspots (the darker areas on the solar surface). Flares can last from a few minutes to some hours.

Since April 15, this was the third X-class ( highest intensity in Watts / m^2) solar flare, stated the data gathered by Centre of Excellence in Space Weather Sciences India (CESSI), operating at the Indian Institute of Science Education and Research (IISER), Kolkata.

Even though not all solar flares are harmful, Earth-bound flares can interfere with telecommunication and GPS-based services, hit satellite and space station operations — especially the sunlight side. High frequency radio signals can be completely lost or rendered of poor quality.

“When solar flares hit, it can lead to ionization in the lower ionospheric levels, resulting in loss of high frequency radio signals,” said Yoshita Baruah, a first-year PhD student at IISER, Kolkata. Solar flares, typically, affect the 3 to 30 MHz radio band which are used for aviation and weather services, among others.

At least two large sunspots (identified as 2993 and 2994), located over the northeast quadrant of the Sun,
have been observed to be active and possessing magnetic complexities.

These have significant potential to emit flares during the next three days, said the latest forecast issued by the Space Weather Prediction Centre at National Oceanic and Atmospheric Administration (NOAA) on Wednesday.

But now, with the sunspot AR12992 having rotated beyond the Sun’s edge when seen from Earth, its activity will be monitored during the upcoming fortnight. “One full rotation of the Sun is completed in 27 days and during the next two weeks, we need to see if any of these sunspots re-emerge,” added Buruah.

According to physicists at CESSI, there have been two X class and 13 M class (second highest intensity in Watts / m2) solar flares reported since April 15. During the past few days, the solar wind speeds, too, have seen an uptick with speed now having increased to 556 km/second on Wednesday. The Sun had shown a similar active phase during the end of March.

Also associated with the latest flaring event was a Coronal Mass Ejection (CME), said fifth-year PhD student at IISER Kolkata, Suvadip Sinha.

“The CME is likely to have emitted from the southwestern limb of the Sun, the same location from where the plasma ejected. But the CME did not affect the Earth,” said Sinha, who has developed a model to track the real-time magnetic field variations on the sun at CESSI.