Atmosphere dynamics of the active region NOAA 11024

TL;DR

This study analyzes the velocity fields in the chromosphere and photosphere of active region NOAA 11024 using multi-wavelength observations, revealing dynamic flux emergence and significant velocity variations across different atmospheric layers.

Contribution

It combines ground-based spectropolarimetric data with space-borne observations to provide high-resolution insights into the velocity dynamics of an active region during flux emergence.

Findings

Detected surge velocities up to -73 km/s in the chromosphere.

Observed predominantly upward motions in the photosphere.

Velocity variations are consistent with magnetic flux emergence.

Abstract

We present results of the study of chromospheric and photospheric line-of-sight velocity fields in the young active region NOAA 11024. Multi-layer, multi-wavelength observational data were used for the analysis of the emerging flux in this active region. Spectropolarimetric observations were carried out with the telescope THEMIS on Tenerife (Canary Islands) on 4 July 2009. In addition, space-borne data from SOHO/MDI, STEREO and GOES were also considered. The combination of data from ground- and space-based telescopes allowed us to study the dynamics of the lower atmosphere of the active region with high spatial, spectral, and temporal resolutions. THEMIS spectra show strong temporal variations of the velocity in the chromosphere and photosphere for different activity features: two pores, active and quiet plage regions, and two surges. The range of variations of the chromospheric line-of-sight velocity at the heights of formation of the H-alpha core was extremely large. Both upward and downward motions were observed in these layers. In particular, a surge with upward velocities up to -73 km/s were detected. In the photosphere, predominantly upward motions were found, varying from -3.1 km/s upflows to 1.4 km/s downflows in different structures. The velocity variations at different levels in the lower atmosphere are compatible with magnetic flux emergence.