Why the composition of the Sun varies

About 17 years ago, J. Martin Laming, an astrophysicist at the U.S. Naval Research Laboratory, theorized why the chemical composition of the Sun’s thin, lowest layer differs from the lower bottom. His theory was recently validated by combined observations of the sun’s magnetic waves from Earth and from space.

His most recent scientific journal article describes how these magnetic waves change the chemical composition in a new process for solar physics or astrophysics, but already known in the optical sciences, as the Nobel Prizes were awarded to Steven Chu in 1997 and Arthur Ashkin in 2018. .

Laming began researching these phenomena in the mid-1990s, publishing the theory in 2004.

“It is satisfying to learn that the new observations demonstrate what ‘is happening’ under the hood ‘in theory, and that it is actually happening on the Sun,” he said.

The sun consists of many layers. Astronomers call its outer layer the solar corona, which is only visible from the earth during a total solar eclipse. All solar activities in the corona are driven by the solar magnetic field. This activity consists of solar flares, coronal mass ejections, rapid solar wind and energetic sun particles. These different manifestations of solar activity are propagated or caused by oscillations or waves on the magnetic field lines.

“The same waves, when they hit the lower solar regions, cause the change in chemical composition, which we see in the corona as this material moves upward,” Laming said. “In this way, the coronal chemical composition offers a new way of understanding waves in the solar atmosphere, and new insights into the origin of solar activity.”

Christoph Englert, head of the space science division of the US Naval Research Laboratory, points out the benefits of predicting the sun’s weather and how Laming’s theory can help predict changes in our ability to communicate on earth.

“We estimate that the sun is 91 percent hydrogen, but the small fraction that is offset by small ions such as iron, silicon or magnesium dominates the radiation output in ultraviolet and X-rays from the corona,” he said. “As the abundance of these ions changes, so does the radiation output.”

“What happens to the sun has a significant effect on the earth’s upper atmosphere, which is important for communications and radar technologies that depend on the over-the-horizon or radio frequency distribution of the earth to space,” he said. Englert said.

It also has an impact on objects in orbit. The radiation is absorbed in the upper atmospheric layers of the earth, causing the upper atmosphere to form plasma, the ionosphere, and expand and contract, affecting the atmospheric resistance on satellites and orbital debris.

“The sun also releases high-energy particles,” Laming said. “They can damage satellites and other space objects. The high-energy particles are microscopic, but it is the velocity that makes them dangerous to electronics, solar panels and navigation equipment in space.”

Englert said that the prediction of solar activity is reliably a long-term goal, which requires us to understand the inner workings of our star. This latest achievement is a step in this direction.

“There’s a long history of advances in astronomy that exploits technological advances, all the way back to Galileo,” Englert said. “We are excited to continue this tradition in support of the U.S. Navy.”