NCCS-Hosted Simulations Bring to Light
a New Type of Coupled Eruption from the Sun
Using the NASA Center for Climate Simulation (NCCS) Discover supercomputer, scientists simulated complex interactions between large structures in our Sun’s atmosphere that unexpectedly produced a new type of “coupled eruption.”
Peter Wyper, Durham University.
Photo by NASA/Kelly Ramos.
Eclipse and satellite images of the Sun reveal large, tapered structures called streamers that stretch out into space from the solar atmosphere, or corona. “Differences in the underlying magnetic field distinguish broad ‘helmet streamers’ from narrow ‘pseudostreamers,’” explained Peter Wyper, assistant professor, Department of Mathematical Sciences, Durham University. “From beneath these tapered canopies, snaking structures known as filaments erupt and expel millions of tons of plasma at high speed into the solar wind.”
Wyper and his colleagues at the NASA Goddard Space Flight Center and University of California, Berkeley describe these first-of-a-kind simulations in a paper recently published in The Astrophysical Journal.
In the research team’s simulations, placing a filament eruption from a pseudostreamer next to a helmet streamer led to the latter blowing its top in a “streamer-blowout eruption" accompanied by a bubble-shaped coronal mass ejection. Scientists have previously seen coupled eruptions involving paired filament ejections that originate beneath a single helmet streamer but not this particular coupling before. “This unexpected coupling produced quite complex internal structure in the ejected bubble and strongly deflected the filament material from its original outward path,” Wyper said.
Simulating this complexity was a task for the 3D Adaptively Refined Magnetohydrodynamics Solver (ARMS) software developed by paper co-authors Spiro Antiochos and Rick DeVore of NASA Goddard’s Heliophysics Science Division and collaborators. To capture the vast differences in spatial scales, ARMS used four refinement levels with each higher level doubling the computational grid resolution.
Dozens of ARMS simulations — including four production runs testing different configurations — used nearly 1.8 million core-hours on the NCCS Discover supercomputer. The simulations produced 162 gigabytes of data, initially saved to Discover’s "nobackup" disk and then archived in mass storage.
“The global, coupled nature of the eruptions that we studied requires simulating nearly the entire solar atmosphere, including the inner solar wind,” Wyper noted. “Access to NCCS supercomputing facilities was critical for obtaining our results, as without those resources, simulations of this scale and ambition would have been difficult to perform and analyze.”
The team made synthetic observations from the simulation data, and the morphology and acceleration of the simulated bubble-like coronal mass ejection compare well with satellite observations.
Moreover, the simulation results highlight the sometimes-interconnected nature of eruptions from our Sun. To fully understand and predict the path of eruptions, scientists need to consider how the erupting structure might couple with the larger-scale magnetic field that surrounds it.
“Although we focused on this coupling in the paper, we actually were surprised that we obtained a coupled eruption,” Wyper explained. “We were not intending to study this aspect of the Sun; our original plan was purely to study the first part of the event, a simple eruption. The subsequent coupling with the global magnetic field was unexpected and new.”
- Wyper, P.F., S.K. Antiochos, C.R. DeVore, B.J. Lynch, J.T. Karpen, and P. Kumar, 2021: A Model for the Coupled Eruption of a Pseudostreamer and Helmet Streamer. Astrophysical Journal, 909, no. 54, doi:10.3847/1538-4357/abd9ca.
Jarrett Cohen, NASA Goddard Space Flight Center