Sunspots
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Sunspot at high spatial resolution (2/3)
Swedish 1m Solar Telescope
This set of images shows the main spot of active region 10425 as observed by the SOUP instrument at the Swedish 1-m Solar Telescope on August 9, 2003. The measurements were made in the Fe I 6302 Å spectral line, which has one of the largest magnetic sensitivities among the lines in the visible solar spectrum. The spot was located mid-way between the disk center and the limb, so there are some projection effects. To better visualize the relation between intensities, magnetic fields and velocities in sunspots, pores and active region plage, the reader is encouraged to go through the three maps in rapid sucession.
The magnetogram image shows the polarity of the magnetic field in the same area. While represents fields pointing to the observer and black fields pointing away from the observer. In this image we can already see projection effects: the part of the penumbra facing the observer is white while the part of the penumbra near the solar limb is darker (upper right and lower left, respectively). The sunspot field is symmetrical around the umbra center, but since the spot is outside of the disk center, we observe different field inclinations in the two parts of the penumbra. This gives rise to different magnetogram signals. The active region plage in the lower right corner is very prominent in the magnetogram. It has fields of positive polarity (white), like the main spot.
Image credit: Göran Scharmer, Kai Langhans, Mats Löfdahl (ISP/Stockholm)
Text credit: Luis Bellot Rubio (IAA-CSIC)
Source: SST Galleries