Why the composition of the sun varies

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

His most recent article in a scientific journal describes how these magnetic waves modify the chemical composition in a completely new process in solar physics or astrophysics, but already known in optical sciences, having been the subject of Nobel prizes awarded to Steven Chu in 1997 and Arthur Ashkin in 2018..

Laming began to explore these phenomena in the mid-1990s and first published the theory in 2004.

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

The Sun is made up of several layers. Astronomers call its outermost layer the solar corona, which is only visible from Earth during a total solar eclipse. All solar activity in the corona is driven by the solar magnetic field. This activity consists of solar flares, coronal mass ejections, high speed solar wind and solar energy particles. These various manifestations of solar activity are all propagated or triggered 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 origins of solar activity.”

Christoph Englert, head of the space science division at the US Naval Research Laboratory, highlights the benefits of predicting the Sun’s weather and how Laming’s theory could help predict changes in our ability to communicate on Earth.

“We estimate that the Sun is 91% hydrogen, but the small fraction represented by minor ions like iron, silicon or magnesium dominates the radiative output of ultraviolet and X-rays from the corona”, a- he declared. “If the abundance of these ions changes, the radiative efficiency changes.”

“What happens on the Sun has significant effects on the Earth’s upper atmosphere, which is important for communication and radar technologies that rely on the propagation of radio frequencies above the horizon or ground-to-space. “Englert said.

It also has an impact on objects in orbit. Radiation is absorbed in Earth’s upper atmospheric layers, causing the upper atmosphere to form plasma, the ionosphere, and expand and contract, influencing atmospheric drag 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 themselves are microscopic, but it’s their speed that makes them dangerous to electronics, solar panels and navigation equipment in space. “

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

“There is a long history of advancements in astronomy that spawned technological advancement, which dates back to Galileo,” Englert said. “We are delighted to continue this tradition in support of the US Navy.”