Multicolor Continuum Analysis of the Solar Granulation in Quiet and Active Regions


A set of narrow-band filtergrams of the solar photosphere recorded in three widely separated true continuum windows and in Mg I b1 with a spatial resolution of about 0.5 arcsec is analyzed. The influence of small-scale magnetic fields on the granulation is studied by comparing various statistical parameters in selected active and quiet regions, and the temperature stratification of faculae at the level of continuum formation is investigated. In active regions there exist more points with enhanced continuum intensity as compared with quiet regions, and there is more power at small spatial scales in active regions, whereas more power exists at large scales in quiet regions. Quiet regions near and far away from a large sunspot do not show any significant difference. It is concluded that changes in the granular pattern near sunspots are caused by the small-scale magnetic fields often found near sunspots. Faculae, identified by their brightness in the Mg I b1 wing, show an enhanced continuum intensity and a reduced ratio between the blue and the red continuum, which is consistent with current flux tube models.

Astrophysical Journal