NJIT Solar Physicists Take Spotlight at NASA's Int'l Supercomputing Conference
NJIT heliophysicists who have developed new ways to forecast explosive events from the interior of the Sun recently captured the attention of international space and computer science communities with their exhibit featured at NASA’s Virtual SC20 Supercomputing Conference.
NJIT Ph.D. student-researchers John Stefan ’22, Andrey Stejko ’21 and Department of Physics Professor Alexander Kosovichev joined scientists from three NASA locations and select universities across the U.S. to present at this year’s virtual conference.
The conference, which is among the most anticipated showcase events each year for high-performance computing and analysis worldwide, featured 35 research projects in all — each powered by NASA’s high-performance supercomputers to do everything from better assessing COVID-19’s global impacts, to helping return humans to the Moon, to searching the cosmos for new exoplanets and more.
Both Stefan’s and Stejko’s research is currently being supported through NASA fellowships.
“As part of our research grants, we were given use of high-performance computing resources at NASA Ames Research Center,” said Stefan. “Ahead of SC20, NASA reached out to us and a few other researchers around the country who use these resources to showcase their accomplishments, and to demonstrate the increasing need for stronger computing infrastructure.”
To help lay the groundwork for a warning system to help protect Earth from damage caused by space weather events, Stefan and Kosovichev have been developing a technique for imaging the solar interior's emerging active regions. The Sun experiences an 11-year cycle driven by a self-sustaining magnetic field called a dynamo, where activity grows over a period of about five years, reaches a peak, and then steadily declines.
Stefan says during the peak of the cycle, the Sun is much more likely to produce active regions, or areas where the magnetic field is especially strong and therefore more prone to solar flares — the solar system’s most powerful explosions. It's considered likely that active regions form when a "clump" of magnetic field rises to the surface from the interior.
To learn more about these key areas, the team used velocity data from NASA’s Solar Dynamics Observatory to generate images of the solar interior, similar to the way ultrasounds map our bodies based on the travel time of sound waves.
“We attempted to image these clumps before they're visible on the surface. It turns out that the resolution of these images is very poor, but they still provide useful information to determine the state of the shallow interior, and we've found that there are certain signatures which hint that an active region will emerge,” explained Stefan. “The next step in our work is applying our methods to a broader range of historical data, about 300 active regions, to see how statistically significant these signatures are. At the end of my studies, I hope to develop a tool which can provide a forecast of active region development.”
Above: A travel time map of the National Oceanic and Atmospheric Administration (NOAA) Active Region 10488 — a huge active region on the Sun — several hours before the magnetic flux has emerged on the Sun’s surface. Lighter areas correspond to shorter travel times, and the strongly negative region is interpreted as the rising magnetic flux. Credit: Stefan/NJIT
Seeing Into the Sun Through Sound
Stejko has also been contributing new modeling tools for solar exploration, called GALE (Global Acoustic Linearized Euler), used for 3D global modeling of the acoustic properties of the Sun. Much like seismology here on Earth, his simulations aim to better probe the solar interior through sound waves generated by convection, or energy transported near the solar surface.
“One of the big questions in astrophysics still sits right at our doorstep; the magnetic field that the Sun creates is a chaotic and unpredictable system that, not only affects the satellites and astronauts that travel into space, but can have dramatic impacts on the Earth as well,” said Stejko. “The structure of the solar powerhouse that creates these magnetic fields has evaded simple explanations for a long time, and much like weather forecasting on Earth, we have turned to computer modeling to understand the system better.”
Above Video: This video shows how a sound wave travels through the interior of the Sun. Increasing gas density strongly results in an increasing sound speed, as shown by how the wave front accelerate as it goes deeper towards the Sun’s core. Measuring and understanding sound waves offers a tool to see variations in density, magnetic fields, and flows that reflect or transfer these acoustic waves. Credit: Stejko/NJIT
Stejko says that when these sound waves interact with flows of gas inside the Sun, they are moved in a certain direction and the resulting frequency shift can offer a 3D image of the Sun’s inner workings. These internal flows are known to affect the Sun’s magnetic cycle. However, typically as helioseismology researchers attempt to look deeper into the solar interior, the signal noise increases, and the data is much harder to interpret.
“To address this, we used thousands of computing hours on NASA's Pleiades supercomputer to create a full 3D acoustic model of the Sun and the mass flows in its interior. This gives us a way to better understand the small changes that different profiles of flow can create, and a better understanding what observed helioseismic signatures actually imply for the structure of the solar interior overall,” said Stejko. “We plan to use our simulations to now see what we can infer over the entire 20-year window that we have been observing the Sun through sound waves.
“We hope that fully integrated 3D global models will finally hold the answer in predicting and understanding the complex web of interactive systems on the Sun that generate the space weather in our cosmic backyard."
Read more about all the work featured at NASA’s Sc20 here: https://www.nas.nasa.gov/SC20/home.html
