NASA's Magnetospheric Multiscale mission has just provided indispensable data explaining the mysteries of the presence of heavy elements in galactic cosmic rays. The discovery is said to have significant implications in the composition of galactic cosmic rays and observed radiation spectra in various astrophysical structures.
What are Galactic Cosmic Rays?
According to NOAA's Space Weather Prediction Center, galactic cosmic rays or GCR are slow, highly energetic background sources of energetic particulates constantly bombarding the planet. These energetic particles consist of a wide range of essential elements like hydrogen, which accounts for roughly 89% of the GCR spectrum, to uranium only found in trace amounts.
The nucleus of these particles is fully ionized, which means that all electrons have been stripped from the element's atoms. Due to this phenomenon, the particles interact and are influenced by the sun's magnetic fields. The sun's strong magnetic fields modulate the GCR flux and spectrums on Earth.
On the other hand, despite what is known about GCR's, scientists have long debated why and how the presence of heavy elements in GCRs become accelerated.
Scientists Discover the Mysteries of Heavy Elements in GCRs
Supernova explosions brought about by dying stars create shockwaves that propagate outwards to space, accelerating ions in their path to very high energies, effectively resulting in GCRs. However, the real question is how heavy ions become accelerated and energized; answers to this age-old mystery can affect the redistribution of mass throughout the known universe and are vital in the formation of heavier, more complex elements.
Dr. Hadi Madanina, the lead author of the study and researcher from the Southwest Research Institute, explains that the heavy ions were initially believed to be insensitive to incoming shockwaves due to their less abundant volume; the shock energy is then consumed by the preponderance of protons as Cleveland American reports.
In the study published in the journal Astrophysical Journal, entitled "Direct Evidence for Magnetic Reflection of Heavy Ions from High Mach Number Collisionless Shocks," researchers observed various intense amplification of magnetic fields near the bow shock; this property has been associated with forceful shocks like supernova remnants. The team then analyzed the different behaviors of ion species at they encountered the bow shock. They discovered that the enhanced fields significantly modified the trajectory of the heavy ions, effectively redirecting them into acceleration zones of the shock.
Although the behavior wasn't expected to occur in heavy ions, researchers discovered direct evidence of the process in alpha particles such as helium ions about 4 times more massive than protons and have 2 times the charge.
David Burgees, the co-author of the study and a professor of mathematics at the Queen Mary University of London, says that the high resolution provided by the Southwest Research Institute-led Magnetospheric Multiscale mission provided clearer pictures of how the shock waves energize heavy elements.
He adds that scientists will be able to use the discoveries to further improve computer models of cosmic ray acceleration in astrophysical collisions.
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