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Massive bursts of solar wind and magnetic fields from the Sun can cause huge sunquakes, according to new UK research.
The results of the study, led by University College London’s Mullard Space Science Laboratory, are being presented by Dr Sergei Zharkovat at the National Astronomy Meeting 2012 in Manchester on Friday, March 30.
Research over the last 10 years has shown that sunquakes can be produced when solar flares—huge explosions of energy in the Sun’s atmosphere—impact and travel into the Sun. The quakes appear as circular ripples on the surface of the Sun.
The new study shows that eruptions of charged particles and magnetic fields known as Coronal Mass Ejections (CMEs) are also able to produce sunquakes.
“Sunquakes are generated by solar flares, when enormous amounts of energy are released high up in the solar atmosphere. Most of the energy goes up into interplanetary space, but a fraction of this energy travels to the Sun’s surface creating a sonic boom that causes the solar interior to oscillate and produce the ripples,” explained Zharkov in an email.
“I sometimes think of sunquakes as thunder to the flare’s lightning, except imagine a lightning over an ocean that is so strong that it creates a tsunami.”
The researchers studied an eruption that took place on Feb. 15, 2011. They found that sunquakes 1,000 times more powerful than the March 2011 Japanese earthquake were triggered at two ends of the erupting rope of magnetic field. The sudden expansion of the magnetic field as it erupts is thought to play a part in the generation of the sunquakes.
The eruption travelled through our solar system at around 600 kilometres per second (1.34 million miles per hour) towards Earth, causing a geomagnetic storm and aurora when it hit the Earth’s atmosphere.
It is for this reason that study of sunquakes is of interest, especially as solar activity is predicted to increase and peak in 2013.
“Sunquakes themselves do not have [an] impact on Earth as they are acoustic waves travelling inside the Sun. But flares and, accompanying them, Coronal Mass Ejections that we have shown play an important role in generating sunquakes, can and do impact Earth,” Zharkov said.
“Sunquakes now form an integral part for our search for understanding of flare and CME phenomena.”
Flares and CMEs have a direct impact on space weather, so understanding how they form could help in predicting when they are going to occur and planning for possible geomagnetic storms, which can affect satellites and radio and GPS equipment on Earth.
But sunquakes are relatively rare, explained Zharkhov. “Known sunquakes were all generated by string solar flares (X and M class), which occur only during the active part of an [11-year] Solar Cycle. However, only a small fraction of such flares produce sunquakes,” he said.
“There is also a chance, however, that sunquakes are more common than we think; it’s just that our means of detecting them are not yet up to scratch.”
Until recently, observation of sunquakes had been hampered by availability of data. “With the (relatively) new NASA’s Solar Dynamics Observatory satellite providing us with practically continuous high resolution and high cadence observations of the Sun, this problem is now solved,” Zharkov said.
Much like geologists use earthquakes to understand the internal structure of our planet, future research will be focused on using sunquakes to learn more about the internal processes of the Sun, said Zharkov. As scientists still don’t fully understand how sunquakes are generated, research will also continue to look for physical explanations of this solar phenomenon.
