The dark component of the photospheric network

Abstract

We examine a high quality Zeeman-analyzed λ-scan through CaI 6103, using a 1/10 Å filter. We find that filter shifts of 0.01 Å produce substantial changes in the contrast seen in the photospheric network in the core of the line, implying that the Doppler velocity in the network is constant to within 0.25 km s⁻¹ or less. Relative line profiles constructed from the λ-scan indicate that the bright network points have smaller equivalent widths than does the background photosphere and are systematically Doppler shifted toward the red. However, we also find numerous small dark points within the magnetic network which exhibit increased equivalent widths. We infer these to be due to magnetic flux tubes which are highly inclined through the photosphere.