Coronal Rain -- an interesting article

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davenn

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For all you solar astronomers out there
An interesting new article from Emily Mason at the NASA’s Goddard Space Flight Centre in Greenbelt, Maryland

April 6, 2019 Unexpected Rain on Sun Links Two Solar Mysteries
For five months in mid 2017, Emily Mason did the same thing every day. Arriving to her office at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, she sat at her desk, opened up her computer, and stared at images of the Sun — all day, every day. “I probably looked through three or five years' worth of data,” Mason estimated. Then, in October 2017, she stopped. She realized she had been looking at the wrong thing all along.


Mason, a graduate student at The Catholic University of America in Washington, D.C., was searching for coronal rain: giant globs of plasma, or electrified gas, that drip from the Sun’s outer atmosphere back to its surface. But she expected to find it in helmet streamers, the million-mile tall magnetic loops — named for their resemblance to a knight’s pointy helmet — that can be seen protruding from the Sun during a solar eclipse. Computer simulations predicted the coronal rain could be found there. Observations of the solar wind, the gas escaping from the Sun and out into space, hinted that the rain might be happening. And if she could just find it, the underlying rain-making physics would have major implications for the 70-year-old mystery of why the Sun’s outer atmosphere, known as the corona, is so much hotter than its surface. But after nearly half a year of searching, Mason just couldn’t find it. “It was a lot of looking,” Mason said, “for something that never ultimately happened.” ...................
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Dave
 

davenn

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Weird stuff !
Yup, the bit that amazes me the most when watching these "loop" videos and there was another one around a year ago. The falling material just seems to materialise out of nowhere at the top of the loop then fall down.

it says this.....
At the loop’s foot points, where it attaches to the Sun’s surface, the plasma is superheated from a few thousand to over 1.8 million degrees Fahrenheit. It then expands up the loop and gathers at its peak, far from the heat source. As the plasma cools, it condenses and gravity lures it down the loop’s legs as coronal rain.
which infers that it is invisible till it gets to the top of the loop, then the cooling/condensation at the top of the loop, even tho it's still a million deg or so makes it "visible"


D
 
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What strikes me is that she still insists on looking for coronal rain in the helmet streamers, after finding it in these small coronal loops connecting to open field lines, because the computer model predicts it. Looking at the image it seems to me that the streamers are too diffuse for rain to condense?
 

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