In this series of posts, we sit down with a few of the keynote speakers of the 246th AAS meeting to learn more about them and their research. You can see a full schedule of their talks here, and read our other interviews here!
Today, I had the wonderful opportunity to have a conversation with Dr. James Klimchuk, a Research Astrophysicist at NASA Goddard Space Flight Center. He is the recipient of the George Ellery Hale Prize and will be giving the George Ellery Hale Prize Lecture at the AAS conference on June 9th, 2025 at 3:40 pm! Dr. Klimchuk’s primary research is the corona of our Sun. His lecture will tell us why the Coronae of the Sun and Other Stars are “so Darned Hot”!
The Sun Has Layers
If you were to dig a hole through the Sun, you would see many different layers, each with its own thermal and nuclear properties. Deep inside the Sun is the core, where nuclear reactions are happening. These nuclear reactions are the power source of the Sun, and photons coming from it need to diffuse through the rest of the Sun before escaping into the Solar System. Right outside the core is the radiative zone, where heat from the core radiates outward into the convective zone. The convective zone carries this heat through convection until, finally, heat can escape into the Solar System through the photosphere. Dr. Klimchuk is primarily interested in understanding what happens beyond this layer, in the solar corona. The Corona of the Sun is incredibly active, with periodic releases of both light and matter.
It has been known for a long time that the Solar Corona, the outermost layer, is significantly hotter than the layers below it. Intuitively, this is confusing because the outermost layer is the farthest away from the heating source in the core, and because the layers of the Sun progressively cool off until the Corona, which suddenly becomes significantly warmer. Dr. Klimchuk’s group has set out to understand why this is.
A Wibbly Wobbly, Hot, Magnetic Ball of Stuff
Because the Sun is so hot, almost all of the matter in the Sun is ionized: it’s a plasma. The motion of this plasma in the photosphere greatly complicates the magnetic field lines in the corona. Magnetic field lines stick out of the photosphere, into the corona, and loop back into the photosphere. Thes field lines stick to patches of the plasma in the photosphere at “foot points”, and as plasma moves around in the photosphere due to convective fluid motion, the magnetic field lines in the corona get all tangled up. Think of a magnetic field line like a rubber band. As the rubber band gets tangled up more and more, it will eventually snap. When it snaps, it releases a lot of magnetic energy into the corona. This is thought to heat the corona!
Dr. Klimchuk has spent his career working in the field of Heliophysics, working to understand the exact physical mechanism of heating the Corona. His group specializes in producing detailed simulations of these magnetic flux tubes, simulating the loop of field lines through the corona. His group aims to tease out all of the minute details of the magnetic and plasma dynamics that drive the coronal heating.
The Man Behind the Science
Dr. Klimchuk is unique in his approach in that he has not restricted himself to just one approach to Astronomy. He has worked with observations, numerical simulations, and even pen-and-paper theory. In fact he has made significant contributions to the field in all three of these “media” of Astronomy. He emphasized that doing so has actually helped him get a better understanding of the subject he studies and even to inspire him to think of unknowns that otherwise wouldn’t have come up. He recommends trying out different approaches to science throughout your career because doing so will make you a more insightful scientist.
An Investment in our Future
Whenever I get the chance, I like to ask scientists this question: “What do you think is the scientific purpose of doing fundamental research? Beyond the science we need to do to build bigger houses or live more lavish lives, is there a pure purpose for science?” I like to see the diversity of answers I get to this question!
Dr. Klimchuk sees fundamental research as a seed for all technology. Every single transformative thing we have built or done can be traced back to some fundamental question someone asked a long time ago. Moreover, you can’t decide which fundamental questions are “worth” asking because they will lead to some “useful” breakthrough in the future. Your only bet is to follow the science and be curious. You just have to pursue lots of fundamental questions, and some of them will pan out!
I had a wonderful time speaking with Dr. Klimchuk! Tune in to his lecture Monday, June 9 at 3:40 pm (Alaska time) at AAS246!
Author: Karthik Yadavalli
Edited by: Margaret Verrico
Featured Image Credit: AAS
