Solar Rain Mystery Solved: Shifting Elemental Abundances Key to Understanding Sun’s Atmospheric Cooling
HONOLULU, HI – October 1, 2025 – Scientists have cracked a long-standing mystery surrounding “solar rain,” the phenomenon of plasma falling back onto the Sun’s surface, by demonstrating that variations in elemental distribution within the corona are critical to understanding its formation.A new study published in The Astrophysical Journal reveals that previous models, which assumed a constant distribution of elements, significantly underestimated the speed at which this cooling process occurs.
For years, researchers have observed coronal rain – condensation of hot plasma in the Sun’s corona – but struggled to explain its rapid formation. Earlier models required hours or even days of heating to account for the phenomenon. However,simulations conducted by a team at the Institute for Astronomy (IfA) at the University of Hawaiʻi at Mānoa,incorporating fluctuating elemental abundances,showed coronal rain condensing in just 35 minutes.
“At present,models assume that the distribution of various elements in the corona is constant throughout space and time,which clearly isn’t the case,” explains Luke Benavitz,an astronomy graduate student at IfA and a co-author of the study.
The team’s simulations suggest that shifting abundances of elements like iron influence radiative energy loss. Spikes in radiation cause temperatures to plummet at the peaks of coronal loops, drawing more material into the loop and triggering a runaway cooling effect that results in coronal rain.
“It’s exciting to see that when we allow elements like iron to change with time, the models finally match what we actually observe on the Sun,” Benavitz said. “It makes the physics come alive in a way that feels real.”
The findings not onyl illuminate the intricacies of solar rain but also suggest a need to re-evaluate current understandings of coronal heating. “We might need to go back to the drawing board on coronal heating, so there’s a lot of new and exciting work to be done,” adds IfA astronomer and study co-author Jeffrey Reep. “This revelation matters because it helps us understand how the Sun really works.”
The researchers conclude that shifting elemental abundances “are critical to understanding the cooling of plasma in the Sun’s atmosphere and, as we have shown, can directly cause coronal rain.” Further research is planned to explore the broader implications of these findings for understanding the Sun’s dynamic behavior.
