(ORDO NEWS) — US and British astrophysicists, using NASA data and advanced imaging technologies, have identified thin, feather-like structures in the Sun’s corona that shape solar wind streams. The results of the study are published in The Astrophysical Journal.
The solar corona is made up of plasma, an ionized gas controlled by a magnetic field that has a complex configuration in the sun’s atmosphere. The surface of the star is permeated with constantly changing combinations of closed contours and open magnetic field lines.
It is through open lines that the solar wind leaves the Sun – a constant stream of solar material that spreads for billions of kilometers and goes far beyond Pluto’s orbit.
The Sun’s magnetic field and associated solar wind shape space weather in and around the solar system, and disturbances in the solar wind affect humans and spacecraft.
Areas of open magnetic field on the Sun create coronal holes – dark spots of relatively low density. Often these holes emit fountains of solar material called plumes over several days. Solar plumes are clearly visible in the ultraviolet rays of the Sun and are perfectly recorded by such devices as NASA’s Solar Dynamics Observatory (SDO) space observatory.
Researchers in the United States and the United Kingdom, using high-resolution SDO observations and imaging technology developed specifically for this project, found that the plumes were composed of much smaller strands of material, which they called feathers. If the size of the entire plume is more than one hundred thousand kilometers, then the width of the feathers is from three to seven thousand kilometers.
“This shows the importance of small-scale structures and processes on the Sun for understanding the large-scale solar wind system and space weather in general,” research director Vadim Uritsky of the Catholic University of America in Washington DC and the Space Flight Center named after Goddard.
Scientists have previously assumed that the solar plumes are heterogeneous inside, but now for the first time they have fixed their internal structure in clear focus. It turned out that feathers are not just elements of the train, they are the building blocks of which the latter are composed. The brightness of the trail depends entirely on the number of feathers.
“For a while, we saw the structure inside and at the base of the plumes,” said fellow study author Judy Karpen, director of the Space Weather Laboratory in the Helio Physical Sciences Division at NASA’s Goddard Space Flight Center. “But now we figured out that the plume itself is a bunch of these denser feathers, which is very different from the concept that we had before.”
The authors also found that each “feather” vibrates on its own, independently of the others. This allowed them to suggest that the small-scale behavior of these structures may be the cause of local disturbances in the solar wind.
Scientists hope that in the future, NASA’s Parker Solar Probe and PUNCH (Polarimeter to Unify the Corona and Heliosphere) missions will take closer images of the sun’s surface, which can be used to study the discovered structures in even greater detail.
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