Plasma properties and Stokes profiles during the lifetime of a photospheric magnetic bright point^⋆

¹ Astrophysics Research Centre, School of Mathematics and Physics, Queen’s University Belfast, BT7 1NN Belfast UK
e-mail: rhewitt05@qub.ac.uk
² Monash Centre for Astrophysics, School of Mathematical Sciences, Monash University, Clayton VIC 3800, Australia

Received: 21 October 2013
Accepted: 28 March 2014

Abstract

Aims. In this paper we aim to investigate the evolution of plasma properties and Stokes parameters in photospheric magnetic bright points using 3D magneto-hydrodynamical simulations and radiative diagnostics of solar granulation.

Methods. Simulated time-dependent radiation parameters and plasma properties were investigated throughout the evolution of a bright point. Synthetic Stokes profiles for the FeI 630.25 nm line were calculated, which also allowed the evolution of the Stokes-I line strength and Stokes-V area and amplitude asymmetries to be investigated.

Results. Our results are consistent with theoretical predictions and published observations describing convective collapse, and confirm this as the bright point formation process. Through degradation of the simulated data to match the spatial resolution of SOT, we show that high spatial resolution is crucial for the detection of changing spectro-polarimetric signatures throughout a magnetic bright point’s lifetime. We also show that the signature downflow associated with the convective collapse process tends towards zero as the radiation intensity in the bright point peaks, because of the magnetic forces present restricting the flow of material in the flux tube.