A comparison between solar plage and network properties

¹ Institute for Solar Physics, Dept. of Astronomy, Stockholm University, Albanova University Center, 10961 Stockholm, Sweden
e-mail: david.buhler@astro.su.se
² Max Planck Institute for Solar System Research, Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany
³ School of Space Research, Kyung Hee University, Yongin, Gyeonggi 446-701, Korea

Received: 6 June 2018
Accepted: 12 July 2019

Abstract

Aims. We compare the properties of kG magnetic structures in the solar network and in active region plage at high spatial resolution.

Methods. Our analysis used six SP scans of the solar disc centre aboard Hinode SOT and inverted the obtained spectra of the photospheric 6302 Å line pair using the 2D SPINOR code.

Results. Photospheric magnetic field concentrations in network and plage areas are on average 1.5 kG strong with inclinations of 10° −20°, and have < 400 m s⁻¹ internal and 2−3 km s⁻¹ external downflows. At the disc centre, the continuum intensity of magnetic field concentrations in the network are on average 10% brighter than the mean quiet Sun, whilst their plage counterparts are 3% darker. A more detailed analysis revealed that all sizes of individual kG patches in the network have 150 G higher field strengths on average, 5% higher continuum contrasts, and 800 m s⁻¹ faster surrounding downflows than similarly sized patches in the plage. The speed of the surrounding downflows also correlates with the patch area, and patches containing pores can produce supersonic flows exceeding 11 km s⁻¹ in individual pixels. Furthermore, the magnetic canopies of kG patches are on average 9° more horizontal in the plage compared to the network.

Conclusions. Most of the differences between the network and plage are due to their different patch size distributions, but the intrinsic differences between similarly sized patches likely results from the modification of the convection photospheric convection with increasing amounts of magnetic flux.