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NASA visualization shows Sun’s artistic side


The beauty of heliophysics: This visualization uses data taken by NASA's Solar Dynamics Observatory (SDO) on 19 June 2010. The specific colors describe which areas on the Sun cooled or heated over a 12-hour period. The use of reds and yellows imply that higher temperatures dominated earlier in the time period, while cooler temperatures dominated later, meaning that the area showed steady cooling over time. The heating happened too quickly and impulsively to be measured. The image compares wavelength 211 (which shows material in the 2 million K range: 1,999,700 °C or 3,599,500 °F) to wavelength 171 (which shows material less than 1 million K: 999,730 °C or 1,799,500 °F). Image courtesy NASA/Viall.

NASA’s Solar Dynamics Observatory (SDO) has transmitted back data on our Sun and space weather at a rate of 1.5 terabytes per day since 2010. Now, researchers have converted some of this data into a visualization of the heating and cooling of plasma in the Sun’s atmosphere; it’s reminiscent of impressionist-style paintings. Some have compared this work to the brush strokes of famous Dutch painter Vincent van Gogh.

“Someone from Kent State University is curating a show about science techniques in art and including our visualizations,” said Nicholeen Viall, a heliophysics researcher at NASA's Goddard Space Flight Center, who was involved in the research.

This work is helping answer the solar coronal heating problem of why the Sun’s corona, which can extend one million kilometers (621,370 miles) above its surface beneath, is about 100 to 600 times hotter than it. Analyzing the Sun’s complex temperature changes was key.

Viall and her colleagues produced solar temperature-change maps by looking at areas of enhanced magnetic fields. They used data from SDO’s on-board Atmospheric Imaging Assembly over a 24-hour period. By comparing the brightness of one pixel at a time over 12 hours in two different wavelengths, they could tell if the plasma was heating or cooling. Software was used to run an iterative comparison for each of the total 160,000 pixels. Then a color-coded map was made of how long the plasma took to heat or cool.  

“I wrote the program using the IDL (Interactive Data Language) programming language,” said Viall. They found that most of the coronal plasma is in a state of cooling after having been rapidly heated by bursts of energy called nanoflares.

“What Nicki and her colleagues’ visualisations do, extremely effectively, is assimilate this data in such a form that it enables us to take advantage of what human beings are intuitively good at; spotting patterns. The image colors used tell us the rate at which different regions are cooling or being heated,” said Stephen Bradshaw, assistant professor of physics and astronomy at William Marsh Rice University, US.

According to Bradshaw, the visualizations provide a convenient way to rigorously test theories and computational models, and will have a significant impact on the research field.

But, distributed computing or multiple computers could help Viall run more and different solar datasets, furthering her research, as computer memory on her desktop is limited. “In an ideal world, I would run the analysis on all 4,000 x 4,000 pixels in the image, instead of 450 x 450 pixels, for the full duration of the mission,” said Viall. “This would allow me to determine if all areas of the Sun are heated in the same way.”

Next, the researchers will repeat visualizations on other areas and at other times to see if they heat differently. They are also working on modeling various aspects that their visualization revealed about the solar corona.

Their latest research is published inthe Astrophysical Journalof IOPscience.

- Adrian Giordani

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