Atmosphere above a large solar pore

TL;DR

This study observes a large solar pore with a light bridge, revealing a filamentary structure similar to a superpenumbra and analyzing chromospheric oscillations, contributing to understanding solar pore dynamics.

Contribution

It provides detailed spectroscopic observations of a solar pore with a light bridge, highlighting its superpenumbra-like structure and chromospheric oscillation properties, which are novel insights.

Findings

Presence of a filamentary structure similar to a superpenumbra

Enhanced chromospheric oscillations in the light bridge

Acoustic power flux insufficient to explain brightness

Abstract

A large solar pore with a granular light bridge was observed on October 15, 2008 with the IBIS spectrometer at the Dunn Solar Telescope and a 69-min long time series of spectral scans in the lines Ca II 854.2 nm and Fe I 617.3 nm was obtained. The intensity and Doppler signals in the Ca II line were separated. This line samples the middle chromosphere in the core and the middle photosphere in the wings. Although no indication of a penumbra is seen in the photosphere, an extended filamentary structure, both in intensity and Doppler signals, is observed in the Ca II line core. An analysis of morphological and dynamical properties of the structure shows a close similarity to a superpenumbra of a sunspot with developed penumbra. A special attention is paid to the light bridge, which is the brightest feature in the pore seen in the Ca II line centre and shows an enhanced power of chromospheric oscillations at 3-5 mHz. Although the acoustic power flux in the light bridge is five times higher than in the "quiet" chromosphere, it cannot explain the observed brightness.