Sunspots
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Sunspot at high spatial resolution (3/3)
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 Dopplergram image shows the line-of-sight velocity of the gas in the solar photosphere. In this case, white represent upward flows, while black represents downward flows. As can be seen, the two parts of the penumbra are also affected by projection effects. This is because the flow of gas is nearly horizontal and radially outwards in the penumbra, so on one side the gas moves toward us and on the other side the gas moves away from us, producing opposite Doppler signals. Note that granules are white (upward motions) and the intergranular lanes are darker (downward motions). Also interesting is the fact that the velocity is significantly reduced in the active region plage in the lower right corner.
Image credit: Göran Scharmer, Kai Langhans, Mats Löfdahl (ISP/Stockholm)
Text credit: Luis Bellot Rubio (IAA-CSIC)
Source: SST Galleries