The magnetic field of our stars originates just 20,000 miles below the surface, and not about 130,000 as all previous theories stated.
An international team of researchers has just solved a solar mystery of 400 years old. Since Galileo Galiei observed for the first time the magnetic activity of the Sun, astronomers have tried to determine where this process originates, mainly responsible for the gigantic spot that has formed on its surface, and that unleashed the last solar storms that affected our planet.
A NASA supercomputer has just told researchers that the sun’s magnetic field originates just 20,000 miles below the surfaceand not about 130,000, as all previous theories claimed.
The new discovery, which has just been published in Nature, will not only help to better understand the dynamic processes of the sun, but would serve to more accurately forecast powerful solar storms. In addition to allowing us to see the northern lights these days in such unlikely settings as Mexico or Spain, the solar eruptions and coronal mass ejections that our star launches towards Earth can seriously damage electrical and telecommunications infrastructure, including GPS navigation tools, satellites in Earth orbit, electrical networks and radio communications. Those this May deactivated the navigation systems of many brands of tractors, forcing many US farmers to stop planting in the middle of the season.
In 1612 Galileo began documenting sunspots caused by its magnetic field. To do this he used the first telescopes and even did it with the naked eye. The spots vary approximately every 11 years. At that time, the sun’s north and south magnetic poles swap places. Right now we are in Solar Cycle 25, which began in December 2019 and will end in 2030. This magnetic activity forms solar spots and flares that expel a large amount of radiation to the closest planets.
As the centuries passed, astronomers made important advances in understanding the physical process that generated the magnetic field, reaching the conclusion that its dynamo had a very deep origin. Now a research team led by Daniel Lecoanet, professor of engineering sciences and applied mathematics at Northwestern’s McCormick School of Engineering, and Geoffrey Vasilprofessor of mathematics at the University of Edinburgh, have been able to run cutting-edge numerical simulations, which for the first time took into account so-called torsional oscillations, a cyclical pattern of how gas and plasma flow in and around the sun.
Since the sun is not solid like The Earth and the Moon do not rotate as a single body. Its rotation varies with latitude. While the poles rotate with a period of approximately 34 days, in the equatorial region it requires just 24 days. Just as the solar magnetic field is 11 years old, torsional oscillations also experience an 11-year cycle.
“It gave us a clue to discover that torsional oscillations only occur near the surface of the sun. Our hypothesis is that the magnetic cycle and torsional oscillations are different manifestations of the same physical process,” says Lecoanet.
Researchers consider the most powerful solar storm ever recorded, which hit Canada in September 1859, as a warning. Carrington Event damaged the country’s fledgling telegraph system. With enough notice, engineers could take steps to prevent catastrophic damage in the future.
“We are concerned about the possibility of even more powerful storms than the Carrington event,” Lecoanet said. “If a storm of similar intensity hit the United States today it would cause between $1 and $2 trillion in damage.”
