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Sharpening the View Image 1
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Sharpening the View (Image 1)

June 30, 2010
Sharpening the View (Image 1) High-resolution image of sunspot produced with the new camera attached to the Dunn Solar Telescope's adaptive optics system (see Here for an edited image depicting uncorrected viewing and the relative size of the Sun). An ultrasharp image of sunspot AR10805 (Sept. 28, 2005, 17:03:47 UTC) shows several objects of current scientific interest. G-band bright points, which indicate the presence of smallscale magnetic flux tubes, are seen near the sunspot and between several granules (columns of hot gas circulating upward). Normally, such features are beyond the grasp of ground-based solar telescopes because of blurring by Earth's turbulent atmosphere. High-order adaptive optics (AO) available at the National Science Foundation's Dunn Solar Telescope in Sunspot, N.M., compensate for much of that blurring, allowing the Dunn to observe up to 7 times sharper at its diffraction limit (theoretical best) of 0.14 arc-second resolution, rather than the 1.0 to 0.5 arc-second resolution normally allowed by Earth's atmosphere. The dark cores of penumbral fibrils and bright penumbral grains are seen as well in the sunspot penumbra (the fluted structures radiating outward from the spot). These features hold the key to understanding the magnetic structure of sunspots and can only be seen in ultra high-resolution images such as this one. Magnetism in solar activity is the "dark energy problem" being tackled in solar physics today. This image was built from a series of 80 images, each 1/100th of a second long (10 ms), taken over a period of 3 seconds by a high-resolution Dalsa 4M30 CCD camera. The image was taken in G-band, a blue part of the spectrum (430.5 nm) where magnetic features stand out in high contrast. The finished image spans an angel of about 56 arc-seconds, equivalent to about 3.2 times the diameter of Earth, or 40,630 km (~25,190 miles), at the visible surface of the Sun. (Date of Image: unknown)


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