Scientists have discovered that meteor-like fireballs in the Sun's atmosphere rain down like shooting star showers during the coronal rain phenomenon.
However, the Sun's "meteors" are not the remnants of passing comets or asteroids, but rather balls of plasma that heat the gas in the atmosphere around them as they fall back to the Sun's surface at speeds as high as 150 kilometres (93 miles) per second.

The discovery of these details, led by solar physicist Patrick Antolin of Northumbria University in the UK, could help scientists learn more about the Sun's atmosphere and why it is strangely and paradoxically much hotter than the surface.
The research, whose preprint server is on arXiv, will be published in the journal Astronomy & Astrophysics and presented this week at the UK Royal Astronomical Society's annual National Astronomy Meeting.

Coronal rain obeys the same physical laws as rain on Earth - except for what it is made of. Heated material rises from the surface and cools as it rises, causing it to fall back down. On Earth, this is usually water. On the Sun, on the other hand, the plasma traces the cyclic magnetic fields that protrude from the solar surface.
We know a little about how coronal rain works, but the European Space Agency's Solar Orbiter (SolO) has given us a surprisingly close view. In March 2022, the probe came within just 48 million kilometres (30 million miles) of our star in the first of such daring manoeuvres. This close encounter, called perihelion, provided astronomers with a wealth of close-up data to study.

This is where Antolin and his colleagues obtained high-resolution data of plasma clumps up to 250 kilometres (155 miles) wide falling down in the coronal shower. They also found that beneath these clumps as they fall back towards the Sun, gas in the solar atmosphere is compressed and heated to about 1 million degrees centigrade. These hot spots last for several minutes as the clusters continue their descent.
Here on Earth, when meteorites fall, something similar (though not as hot) happens, turning rock fragments into fireballs that either erode or explode from heat and pressure. But the researchers found that things are a little different on the Sun.

Because the solar atmosphere is so thin, plasma clusters do not experience the kind of ablation experienced by meteorites on Earth. And the loops of the magnetic field act as a kind of tunnel through which the clumps pass. Therefore, the plasma balls probably reach the surface intact and cause a brief flash of heat and light when they land. This was also imaged by SolO.
But magnetic loops also prevent the plasma from forming a tail, as meteorites do. This means they are much harder to see.

"SolO orbits close enough to the Sun that it can detect small-scale phenomena occurring inside the corona, such as the effect of rain on the corona, providing us with a valuable indirect probe that is crucial for understanding the composition and thermodynamics of the coronal environment," says Antolin.
"Even just detecting coronal rain is a big step forward for solar physics because it gives us important clues about big solar mysteries, such as how the sun is heated to millions of degrees."

 

Source: https://www.sciencealert.com/