Sunspot near the limb

Swedish 1m Solar Telescope

This image shows a sunspot near the solar limb as observed through a continuum filter at 436.5 nm. Because of projection effects, granules appear elongated in the direction parallel to the limb and shorter perpendicular to it (the limb is to the left of the image).

Bright small-scale features can be observed on the right side of some granules (i.e., on the side away from the limb). They are called faculae and harbor intense magnetic fields. The gas in their interior is less dense than in the surroundings, so they are more transparent. As a consequence, they allow to see the hot walls of the granule that lie behind them, appearing bright.

The observations were reconstructed using a phase diversity technique.

Image credit: Vasily Zakharov (MPS)

Text credit: Luis Bellot Rubio (IAA-CSIC)

Source: SST Gallery