SDO Greatly Increases Accuracy Of Radiation Measurement From Solar Activity

NASA's Solar Dynamics Observatory, or SDO, has provided scientists new information about solar flares indicating an increase in strength and longevity that is more than previously thought. Solar flares are intense bursts of radiation from the release of magnetic energy associated with sunspots. They are the solar system's largest explosive events and are seen as bright areas on the sun. Their energy can reach Earth's atmosphere and affect operations of Earth-orbiting communication and navigation satellites.

NASA Image Of The Sun

Using SDO's Extreme ultraviolet Variability Experiment (EVE) instrument, scientists have observed that radiation from solar flares continue for up to five hours beyond the main phase. The new data also show the total energy from this extended phase of the solar flare's peak sometimes has more energy than the initial event. "Previous observations considered a few seconds or minutes to be the normal part of the flare process," said Lika Guhathakurta, lead program scientist for NASA's Living with a Star Program at the agency's Headquarters in Washington. "This new data will increase our understanding of flare physics and the consequences in near-Earth space where many scientific and commercial satellites reside."  

On Nov. 3, 2010, SDO observed a solar flare. Scientists working on the project say that if they had only measured the effects of the flare as it initially happened, they would have underestimated the amount of energy shooting into Earth's atmosphere by 70 percent. SDO's new observations provide a much more accurate estimation of the total energy solar flares put into Earth's environment. "For decades, our standard for flares has been to watch the X-rays as they happen and see when they peak," said Tom Woods, a space scientist at the University of Colorado in Boulder and principal author on a paper in Wednesday's online edition of Astrophysical Journal. "But we were seeing peaks that didn't correspond to the X-rays."

During the course of a year, the team used EVE to map each wavelength of light as it strengthened, peaked, and diminished over time. EVE records data every 10 seconds and has observed many flares. Previous instruments only measured every 90 minutes or didn't look at all wavelengths simultaneously as SDO can. 

To compliment the EVE graphical data, scientists used images from another SDO instrument, the Advanced Imaging Assembly (AIA). Analysis of these images showed the main flare eruption and its extended phase in the form of magnetic field lines called coronal loops that appeared far above the original eruption site. These extra loops were longer and became brighter later than the loops from the main flare and also were physically set apart from those of the main flare.

Because this previously unrealized extra source of energy from flares also is impacting Earth's atmosphere, Woods and his colleagues are studying how the late phase flares can influence space weather. Space weather caused by solar flares can affect communication and navigation systems, satellite drag and the decay of orbital debris.

FMI: www.nasa.gov/sunearth