Vector spectropolarimetry of dark-cored penumbral filaments with Hinode

TL;DR

This study uses high-resolution spectropolarimetric data from Hinode to analyze dark-cored penumbral filaments, revealing their magnetic and flow properties and supporting the flux tube model of Evershed flows.

Contribution

First detailed spectropolarimetric analysis of dark-cored penumbral filaments with Hinode, showing their magnetic inclination, flow dynamics, and relation to flux tubes.

Findings

Dark-cored filaments are more prominent in polarized light.

Magnetic fields are weaker and more inclined in dark cores.

Strong Evershed flows of 6-7 km/s are observed.

Abstract

We present spectropolarimetric measurements of dark-cored penumbral filaments taken with Hinode at a resolution of 0.3". Our observations demonstrate that dark-cored filaments are more prominent in polarized light than in continuum intensity. Far from disk center, the Stokes profiles emerging from these structures are very asymmetric and show evidence for magnetic fields of different inclinations along the line of sight, together with strong Evershed flows of at least 6-7 km/s. In sunspots closer to disk center, dark-cored penumbral filaments exhibit regular Stokes profiles with little asymmetries due to the vanishing line-of-sight component of the horizontal Evershed flow. An inversion of the observed spectra indicates that the magnetic field is weaker and more inclined in the dark cores as compared with the surrounding bright structures. This is compatible with the idea that dark-cored filaments are the manifestation of flux tubes carrying hot Evershed flows.