Evershed effect

The Evershed effect refers to the observed radial outflow of plasma from sunspot regions in the solar atmosphere, particularly in the photosphere and chromosphere. Named after the British astronomer F. W. Evershed, who described it in the early 20th century, this effect is characterized by the detection of a blue shift in spectral lines in sunspot penumbrae, indicating that material is moving outward at high speeds.