The Sun is not what we thought it was? There is something else beyond the corona!

Scientists trace solar plasma to high-energy particles

The findings could help researchers predict dangerous space weather.

Close-up of the Sun depicting surface activity and the solar corona

(Image credit: Dr. Pixel/Getty Images)

Scientists may have discovered how and when high-energy particles bombard Earth and other objects emerging from harsh environments such as the sun's atmosphere.

These high-energy particles pose risks to delicate satellite technology and astronauts, and can even affect aircraft flying over the Arctic Circle. Although researchers have studied these examples for decades, it remains difficult to clearly understand the patterns when unexpected events may occur and to predict the dangers when they may occur.

In the latest study, scientists identified the plasma in the sun's outer atmosphere as a source of high-energy particles based on supercomputer simulations.

"This exciting new research will allow us to better understand the origins of solar energetic particles and improve models for forecasting space weather events, which is a key goal for NASA and other space agencies and governments around the world," Luca Comisso, a researcher at Columbia University and co-author of the study, said in a statement.

The sun's outer atmosphere — the corona — is made of plasma, meaning violent conditions strip atoms of their electrons.

Solar scientists believe that high-energy particles are produced in this highly turbulent sea of ​​stripped atoms (ions).

However, this is difficult to study because plasma motion is irregular and unpredictable, so how and when high-energy particles are produced has always been a mystery.

Comisso and Lorenzo Sironi, also of Colombia, refined the simulations using supercomputers at NASA's Columbia and National Energy Research Scientific Computing Center to simulate the precise motion of electrons and ions in the solar plasma. This created an excellent proxy for the corona, providing the most detailed data yet on when and how high-energy particles form in the region.

Simulations show that magnetic fields in the corona can accelerate electrons and ions to nearly the speed of light and launch them into space.

The research helps resolve a question that scientists have pondered since 1949, when Enrico Fermi first began studying magnetic fields in space as the source of high-energy particles observed bombarding Earth's atmosphere. Fermi's work led physicists to think that the sun's plasma might be behind these particles, with others being hurled toward Earth from deep space. But proving this hypothesis has been challenging.

While the team's results are based on simulations, the space agency's Parker Solar Probe could help further validate the research, Commisso said.

Parker Solar Probe has been observing our star since the spacecraft launched in 2018. Part of its mission is to study the Sun's turbulent outer atmosphere. This means Parker Solar Probe can directly observe the distribution of high-energy particles produced in the solar corona.

The findings of the new work have implications beyond the solar system, too. All stars are composed primarily of plasma, meaning that the vast majority of matter that astronomers see is in this state of matter (rather than gas, liquid, or solid). A better understanding of how plasmas accelerate particles could explain not only the high-energy particles seen around the sun and other stars, but also around other cosmic objects, such as neutron stars and black holes.

This opens the door to new ways in which we might look in the future at how distant stars, black holes and neutron stars produce their own high-energy electrons.

"Our results are centered on the Sun, but can also be seen as a better understanding of how stars located near distant black holes produce high-energy particles," Commisso said.

"We can only scratch the surface of how these particles are created in the universe through supercomputer simulations."

The team's research was published in the Astrophysical Journal Letters on September 13.

Related knowledge

A neutron star is one of the few possible endpoints of a star after it has reached the end of its evolution and exploded in a supernova due to gravitational collapse. After the hydrogen, helium, carbon and other elements in the core of a star are exhausted in nuclear fusion reactions and eventually transformed into iron, it can no longer obtain energy from fusion reactions. The outer material that loses the support of thermal radiation pressure will fall rapidly toward the core due to gravity, which may cause the kinetic energy of the outer shell to be converted into thermal energy and explode outward to produce a supernova explosion, or, depending on the mass of the star, the inner region of the star will be compressed into a white dwarf, neutron star or black hole.

BY:Robert Lea

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