Resistive Emergence of Undulatory Flux Tubes

• DOI: 10.1086/423891
• Publication Date: 2004-10-26T18:17:21Z
• Authors: E. Pariat; G. Aulanier; B. Schmieder; M. K. Georgoulis; D. M. Rust; P. N. Bernasconi
• Keywords: Photosphere; Chromosphere; Field line; Flux tube; Flare; Sunspot; Magnetogram; Solar flare

During its 2000 January flight, the Flare Genesis Experiment observed gradual emergence of a bipolar active region, by recording series high-resolution photospheric vector magnetograms and images in blue wing Hα line. Previous analyses these data revealed occurrence many small-scale, transient brightenings identified as Ellerman bombs (EBs). They occur during flux emergence, them are located near moving magnetic dipoles which field is nearly tangential to photosphere. A linear force-free extrapolation one was performed study topology small-scale EBs their possible role process. We found that 23 out 47 cospatial with bald patches (BPs), while 15 at footpoints very flat separatrix lines passing through distant BPs. conclude can be due reconnection, not only BP locations, but also along separatrices, occurring low chromosphere. The topological analysis reveals, for first time, BPs linked hierarchy elongated tubes showing aperiodic spatial undulations, whose wavelengths typically above threshold Parker instability. These findings suggest arch filament systems coronal loops do result from smooth large-scale Ω-loops below photosphere, rather rise undulatory upper parts emerge because instability dipped lower reconnection. then signature this resistive tubes.