Data from NASA’s Solar Dynamics Observatory offer clues about sun’s coronal irradiance
A pair of researchers with Aberystwyth University in the U.K. has used data from NASA’s Solar Dynamics Observatory to learn more about how the sun’s corona behaves over differing stages of its 11-year cycle.
In their paper published in the open access site Science Advances, Huw Morgan and Youra Taroyan describe attributes of the sun they observed over time and what they discovered about the “quiet corona” and its possible impact on us back here on Earth.
As the researchers note, most research to date regarding the sun’s corona has covered relatively small datasets, which provides only a limited view of what happens with the sun over longer periods of time—specifically, over the course of an entire coronal cycle. But now, thanks to NASA’s Solar Dynamics Observatory, the pair were able to look at data that covered the time between 2010 and 2017, which covers a large portion of one cycle.
Scientists have known for some time that the corona experiences solar cycles of approximately 11 years—solar flare activity grows and ebbs over the course of a single cycle. But until now, there has been no way to measure what happens over the course of a single cycle to explain the changes that occur.
In their analyses of the data, the researchers focused on what scientists call the quiet corona—the part of the corona that remains relatively quiet while sunspots are occurring in other areas. It is a little-researched area, the researchers note, due to the more attractive sunspot areas. They also looked at extreme ultraviolet irradiance emitted from different coronal regions. They report that they found that all throughout a cycle, the quiet corona dominated emissions of EUV and that more active regions demonstrated higher variability. But they also found that main emission measurements of both the quiet corona and those regions that were more active were what they described as “remarkably constant.” Their findings demonstrate, the pair note, that monitoring sunspots is not an adequate means for predicting EUV irradiance—more measurements and study are required to better understand the factors at play.
Coronal temperature
Read more at Phys.org
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