Modeling of active neutral atoms to study solar flares and coronal mass ejections

Solar flares and coronal mass ejections (CMEs) are some of the most energetic processes in the solar system, showering Earth’s magnetic field with billions of tons of high-energy plasma gas, which can disrupt power grids, satellites, and communications networks. Understanding the fundamental particle acceleration process involved in solar large-energy particle (SEP) events like this has been one of the central problems in heliophysics research.

Dr. Zhang Li, a professor in the Department of Space Sciences at the University of Alabama in Huntsville (UAH), is the first author of a paper on Astrophysical Journal entitled “Modeling of Solar Neutral Atoms from CME-Driven Solar Flares and Shocks” which shows – for the first time – how active neutral atomsor ENAs, as a new method to probe the acceleration process in large SEP events, as well as to distinguish between the two sites of acceleration: large episodes in solar flares and shocks driven by the CME.

“This action is likely to excite [heliophysics] Society should think more about the generation and proliferation of solar ENA particles, says Dr. Lee. “The paper demonstrates for the first time that ENAs can be used to differentiate accelerated CME/Flare SEP, laying the necessary theoretical foundation for the future measurement potential of solar ENAs.”

“Dr. Lee’s work presents a groundbreaking new approach to remotely probing the physics of particle acceleration in the heliosphere,” said Dr. Space Science.

“This expands an already large effort in the Department of Space Sciences to use ENAs to explore remote regions of the heliosphere, where we use ENAs that were created at the far frontiers of the heliosphere and the field.” interstellar medium To explore the plasma physics of those regions.”

“The ultimate goal of using ENAs is to obtain different physical parameters at the sites of acceleration,” notes Dr. Lee. Scientists know that particles can be accelerated in two possible locations: either Solar flares or trauma-induced CME. However, what is the most efficient site for particle acceleration? Which site can accelerate particles to higher energies? These are often debated questions and we don’t know the answer.”

The main barrier to resolving these mysteries through experimental observation is the Sun itself, as a basic understanding of the conditions near the Sun and the physical processes involved in producing SEP events is hampered by the inability to make direct measurements near the accelerator sites.

ENAs represent a potential new way of providing answers, because they are particle neutral (hydrogen atoms) that are formed from protons from variable exchange reactions. Because it is neutral, it is not affected by magnetic fields.

“This is very important, because these neutral particles are not affected by the MHD solar wind [magnetohydrodynamic] Dr. Lee explains: Turbulence as it propagates from the Sun to observers. “In comparison, protons, ions and electrons, because they are charged, their propagation from the Sun to Earth is distorted by the magnetic field of the solar wind. The interacting amino acids therefore carry all the physical information about the location of the acceleration. So, observing them provides a whole new opportunity to constrain the acceleration of fundamental particles.” .

Also, energetic atoms can reveal their secrets at a distance of one astronomical unit, or about 150 million kilometers, from the Sun, where the flux of essential amino acids is at a level that can still be measured by a dedicated ENA detector. The quest to retrieve this data may eventually lead to a new NASA solar mission to better understand these particles and how large SEP events arise to affect Earth’s magnetosphere.

“Our simulations form a theoretical basis for interpreting future ENA observations,” notes Dr. Lee. It is possible that such observations will be on NASA’s radar as a future mission, for example, the NASA SMEX mission, to dedicate to the solar ENA study. A dedicated ENA mission that filters more charged SEPs and goes directly after these ENA measurements could provide new information about the solar acceleration. SEP close to the sun and help solve long-standing questions that have baffled the community.”

In fact, the new NASA mission that Dr. Zank is a co-investigator on, called IMAP (Interstellar Mapping and Acceleration Probe), will actually have ENA instruments in 1 astronomical unit Able to measure ENAs generated in both the outer reaches of the heliosphere as well as originating from the Sun.