A Northumbria University astronomer has led a study which has discovered a phenomena similar to shooting stars on the sun.
Patrick Antolin, an assistant professor in the department of mathematics, physics and electrical engineering, will present the findings this week at the National Astronomy Meeting (NAM 2023). Observations from the European Space Agency's Solar Orbiter (SolO) unveiled never-before-seen falling star-type events, or meteor-like fireballs occurring within the plasma displays known as coronal rain.
Though it does not include real water, coronal rain is a condensation process in which some of the sun's fiery material clumps together as a result of sudden and localised drops in temperature. The sun's corona, the outermost part of its atmosphere, is formed of gas at million degree temperatures.
Rapid drops in temperature produce super-dense clumps of plasma as wide as 250km, with gravity pulling these balls back towards the sun at more than 100km per second. Dr Antolin said: "The inner solar corona is so hot we may never be able to probe it in situ with a spacecraft.
"However, SolO orbits close enough to the sun that it can detect small-scale phenomena occurring within the corona, such as the effect of the rain on the corona, allowing us a precious indirect probe of the coronal environment that is crucial to understanding its composition and thermodynamics. Just detecting coronal rain is a huge step forward for solar physics because it gives us important clues about the major solar mysteries, such as how it is heated to millions of degrees.”
He joked: “If humans were alien beings capable of living on the sun’s surface, we would constantly be rewarded with amazing views of shooting stars, but we would need to watch out for our heads."
Along with the first super-high-resolution images of these coronal rain clumps, SolO observed the heating and compression of gas immediately underneath them. Experts suggest the resulting spike in intensity below the clumps indicates that the gas is heated to a million degrees, which lasts for a few minutes as they fall.
On earth, shooting stars occur when meteoroids, or space objects ranging in size from dust grains to small asteroids, enter the planet's atmosphere at high speeds and burn up. Most do not make it to the ground, and the few that do so without disintegrating can produce huge craters.
However, the sun's corona is thin and low in density and does not strip much material off the clumps, therefore scientists believe that most of the 'shooting stars' make it to the solar surface intact. Their impacts had not been observed until now, but observations have revealed this process can produce a brief, strong brightening with an upward surge of material and shockwaves that reheat the gas above.
