CRISP Spectropolarimetric Imaging of Penumbral Fine Structure

TL;DR

This study uses high-resolution spectropolarimetric imaging to analyze the fine magnetic and structural details of penumbral features in a sunspot, revealing complex magnetic variations and potential convective upflows.

Contribution

First high-resolution spectropolarimetric analysis of penumbral fine structure revealing detailed magnetic variations and possible upflow regions.

Findings

Large magnetic field variations over dark-cored structures

Identification of spines separated by 1.6 arcsec with inclination differences

Detection of a nearly vertical, weaker magnetic structure near bright filaments

Abstract

We discuss penumbral fine structure in a small part of a pore, observed with the CRISP imaging spectropolarimeter at the Swedish 1-m Solar Telescope (SST), close to its diffraction limit of 0.16 arcsec. Milne-Eddington inversions applied to these Stokes data reveal large variations of field strength and inclination angle over dark-cored penumbral intrusions and a dark-cored light bridge. The mid-outer part of this penumbra structure shows 0.3 arcsec wide spines, separated by 1.6 arcsec (1200 km) and associated with 30 deg inclination variations. Between these spines, there are no small-scale magnetic structures that easily can be be identified with individual flux tubes. A structure with nearly 10 deg more vertical and weaker magnetic field is seen midways between two spines. This structure is co-spatial with the brightest penumbral filament, possibly indicating the location of a convective upflow from below.