Spectropolarimetery of umbral fine structures from Hinode: Evidence for magnetoconvection

Abstract

We present spectropolarimetric analysis of umbral dots and a light bridge fragment that show dark lanes in G-band images. Umbral dots show upflow as well as associated positive Stokes V area asymmetry in their central parts. Larger umbral dots show down flow patches in their surrounding parts that are associated with negative Stokes V area asymmetry. Umbral dots show weaker magnetic field in central part and higher magnetic field in peripheral area. Umbral fine structures are much better visible in total circularly polarized light than in continuum intensity. Umbral dots show a temperature deficit above dark lanes. The magnetic field inclination show a cusp structure above umbral dots and a light bridge fragment. We compare our observational findings with 3D magnetohydrodynamic simulations.

Accepted for publication in MNRAS, 6 pages, 6 figures

References in corpus (8)

• Detection of sea-serpent field lines in sunspot penumbrae
• Detection of opposite polarities in a sunspot light bridge: evidence of low-altitude magnetic reconnection
• Evidence of magnetic field wrapping around penumbral filaments
• Vector spectropolarimetry of dark-cored penumbral filaments with Hinode
• Heat transfer in sunspot penumbrae. Origin of dark-cored penumbral filaments
• The structure of sunspot penumbrae IV. MHS equilibrium for penumbral flux tubes and the origin of dark core penumbral filaments and penumbral grains
• Hinode observations reveal boundary layers of magnetic elements in the solar photosphere
• Enhanced Joule Heating in Umbral Dots