Sunspots
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Sunspots, pores, and abnormal granules
Swedish 1-m Solar Telescope
Sunspots are the largest manifestation of magnetic fields in the solar photosphere and appear darker than the surrounding photosphere in which convective heat transport takes place in the form of granulation. The details of the heat transport within sunspots are still under debate. It is clear, however, that it is of convective origin. The convective transport of heat must take place even in the coolest parts of sunspots, since neither heat conduction nor radiative heat transport suffices to sustain the observed umbral temperatures.
The image shows the central part of active region 10786 consisting of small pores and many abnormal granules. Bright points in the region appear to be smaller and more concentrated than those around the sunspot located in the right corner of the image. The simultaneous magnetogram shows magnetic fields everywhere. The observations were carried out with the SOUP instrument at the Swedish 1-m Solar Telescope (ISP, Stockholm University) through a wide-band filter centered at 6302.5 Å.
Image credit: Jose Antonio Bonet (IAC)
Publication: Ishikawa et al, 2007, Astronomy & Astrophysics, 472, 911–918