Universe Today
What can Helium-3 (3He) being discharged from the Sun teach us about 3He creation and the Sun’s activity? This is what a recent study published in The Astrophysical Journal hopes to address as an international team of researchers investigated 3He-rich solar energetic particles (SEPs) emitted by the Sun in late 2023. This study has the potential to help astronomers better understand how solar activity could contribute to the production of 3He, the latter of which remains one of the most desired substances due to its potential for nuclear fusion technology on Earth.
For the study, the researchers used the joint NASA-ESA Solar Orbiter to observe the SEPs between October 24-25, 2023, which is currently located at 0.47 astronomical units (AU) from the Sun, or just under halfway between the Sun and the Earth. While SEPs are produced from solar flares or coronal mass ejections (CMEs), which happen regularly, SEPs typically release substances with increased levels of heavy ions like iron. Heavy ions are classified as possessing an atomic number (Z) greater than 10. However, the iron content (Z= 26) in this SEP was found to be normal, with the researchers surprised to discover increased levels of carbon (Z = 6), nitrogen (Z = 7), silicon (Z = 14), and sulfur (Z = 16) within the SEP.
The team then conducted a follow-up observation with NASA’s Solar Dynamics Observatory, which orbits the Earth in a circular, geosynchronous orbit at an altitude of 35,789 kilometers (22,238 miles), so significantly farther from the Sun than Solar Orbiter. In the end, SDO successfully identified the source of the SEP as a solar jet emanating from coronal hole, which is an area of the Sun where open magnetic field lines enable solar winds to escape to space and are often darker in color compared to the rest of the Sun’s surface.
“Surprisingly, the magnetic field strength in this region was weak, more typical of quiet solar areas rather than active regions,” said Dr. Radoslav Bučík, who is an astrophysicist at the Southwest Research Institute and lead author of the study. “This finding supports earlier theories suggesting that 3He enrichment is more likely in weakly magnetized plasma, where turbulence is minimal.”
Other Helium-3 Sources
The Sun produces 3He from the nuclear fusion occurring in its massive core when it converts hydrogen to helium. While this is part of the Sun’s natural processes that enable our planet to sustain life, producing 3He in a laboratory or other Earth-based setting has proven incredibly difficult due to the massive temperatures that have to be duplicated, often requiring a minimum of 100 million degrees Celsius (180 million degrees Fahrenheit).
While the Earth’s mantle contains traces of 3He from the planet’s formation, its decay over billions of years has converted most of the original 3He to Helium-4 (4He). Therefore, scientists have hypothesized that the closest location to obtain active samples of 3He is the lunar surface due to the solar wind’s daily bombardment, resulting in 3He becoming embedded in the lunar regolith (dust). However, it is estimated that successful processing of 1 gram (0.025 ounces) of 3He would require approximately 150 tons of lunar regolith to be mined. Additionally, successful nuclear fusion here on Earth has yet to be realized.
While humanity continues to struggle with nuclear fusion and the need for 3He, this study demonstrates the awesome power of the Sun and how much we still don’t know about its complex and intricate processes responsible for providing life-giving power here on Earth.
What new discoveries about solar activity and 3He will astronomers make in the coming years and decades? Only time will tell, and this is why we science!
As always, keep doing science & keep looking up!
