Atmosphere above a large solar pore

M Sobotka,M Švanda,D Del Moro,P Heinzel,J Jurčák

doi:10.1088/1742-6596/440/1/012049

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.

Highlights

Magnetic field lines are observed to be nearly vertical in centres of pores and inclined by about 40◦ to 60◦ at their edges [3, 4]
We studied the photosphere and chromosphere above a large solar pore with a granular LB using spectroscopic observations with spatial resolution of 0′′.3–0′′.4 in the line Ca II 854.2 nm and photospheric Fe I lines
We have shown that in the chromospheric filamentary structure around the pore, observed in the Ca II line core and Doppler maps, the inverse Evershed effect and running waves are present

Summary

Introduction

Magnetic field lines are observed to be nearly vertical in centres of pores and inclined by about 40◦ to 60◦ at their edges [3, 4]. The distance of the two wavelength points (“slits”) was 36 pm, so that the “slits” were located in the inner wings near the line core, where the intensity gradient of the profile is at maximum and the effective formation height in the atmosphere is approximately 1000 km. A filamentary structure around the pore, composed of radially oriented bright and dark fibrils, is clearly seen in the line-centre intensity and Doppler maps.

Results

Conclusion