How can x-rays help reveal the mysteries of the sun?

19 Jun 2018

Sun surface with solar flares. Image: janez volmajer/Shutterstock

Dr Lindsay Glesener is using x-ray data to better understand high-energy physics in our nearest star. She spoke to Dr Claire O’Connell.

In Ireland this year, we are a little better acquainted with the sun than usual thanks to a bout of glorious weather. But there is still plenty that science doesn’t know about our closest star, such as how it generates high-energy flares that could affect our communications and power networks on Earth.

Dr Lindsay Glesener is using x-ray data to probe the mysteries of solar physics, and she will give a public talk about her work tomorrow (20 June) in Dublin.

High-energy knockouts

Glesener, an assistant professor at the University of Minnesota School of Physics and Astronomy, is particularly interested in how the sun accelerates particles, visible as solar flares and coronal mass ejections that roil on the star’s surface.

“The sun spits out energetic particles and throws plasma at us [on Earth] sometimes,” said Glesener. “We are mostly protected by Earth’s magnetic atmosphere, but there’s a potential for big events to affect power grids and spacecraft in Earth’s orbit.”

Knowing that such an event is likely means we could take steps to protect power grids as well as objects and even astronauts that could be affected, noted Glesener. “If we can study the origin of these big events at the sun, maybe we could even get to a point where we could predict them.”

team in blue overalls gathered around rocket

Image: Dr Lindsay Glesener

To get more insight into the high-energy physics of the sun, Glesener looks at x-ray data, and she is in Ireland this week to take part in the 17th RHESSI workshop hosted by Trinity College Dublin.

The focus is on the Reuven Ramaty High-Energy Solar Spectroscopic Imager (RHESSI), a NASA solar flare observer. “The RHESSI mission is 16 years old, but it is one of the cutting-edge instruments that is telling us about high-energy aspects of the sun,” explained Glesener.

“[Looking at] x-rays can tell us about the highest-energy things that are happening: the explosions, the flares, the ejections of plasma.”

Mysteries of the sun

Glesener wants to find out more about how particles get accelerated in these intense events. “When plasma gets ejected [from the sun] you see the kinds of energies that you would see in particle accelerators and we don’t understand what causes that,” she said. “We can learn a lot by studying the x-rays that those accelerated particles emit.”

There are plenty of other questions to be answered about the sun, such as how the corona (the outer aura of plasma around the star) gets so hot. “The surface of the sun is about 6,000 degrees [Celsius] but the corona is at millions of degrees,” she said. “We don’t know how the outer part is the hottest.”

Desert launches

Part of Glesener’s research looks at building new instruments that can be put into space to observe the sun. “It’s hard to get to space; getting through the atmosphere and building something that is robust enough to survive is really difficult,” she said. “So, a big part of my work is to develop new instrumentation that will eventually be flown on satellites and spacecraft.”

Testing them out often involves trekking into the desert, strapping the instrumentation to sounding rockets, then firing them into space. “We try them out on a small scale, and you get the rocket and instruments back,” she said. “It’s quite exhilarating.”

rocket with team in front and blue sky with clouds in background

Image: Dr Lindsay Glesener

Pivot into physics

Glesener didn’t immediately begin her career in physics after school; instead, she started in ballet. “I joined ballet company when I graduated from high school,” she said. “In high school, I had a fantastic physics class. I wasn’t into it at the time, but in retrospect I was glad I had it.”

That’s because when she went to university, she was looking for something to study and was inspired to choose science. “Once I started studying physics in college, I was very sure that was what I wanted to do,” she said.

Inspiring questions

In her talk in Dublin tomorrow, Glesener will explain her research in high-energy solar physics and take the audience on a ‘field trip’ through pictures and videos of the sounding rocket launches. “I’ll be talking not only about what we are studying, but what it is like to be a scientist,” she said.

For students of physics, she has the following advice: “If you don’t understand things at first, don’t be put off – that is normal,” she said. “In research, we are often struggling with questions we don’t understand how to answer right away.”

Dr Lindsay Glesener will give a free, public talk on ‘The Mysteries of the Sun: Explosions on our Closest Star’ at Trinity College Dublin on Wednesday 20 June at 7pm. Register here.

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Dr Claire O’Connell is a scientist-turned-writer with a PhD in cell biology and a master’s in science communication