On 2D radiative transfer in solar granulation. The case of Fe I lines

Abstract

The effects have been investigated of non-vertical radiative transfer on the formation of neutral iron spectral lines in inhomogeneous photosphere of the Sun. The non-vertical effects, as well as deviations from LTE, smooth the contrast of solar granulation in equivalent widths of solar absorption lines. For the central residual intensities of moderate and strong lines, on the contrary to weak lines, these effects enhance the granulation contrast. It was found, that the negative dependency of equivalent width on intensity in continuous spectrum decays due to the non-vertical effects for Fe I lines.