A Tale of Two Emergences

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Wednesday, July 13, 2016

In June 2013, the two scientific instruments onboard the second Sunrise mission witnessed, in detail, a small-scale magnetic flux emergence event as part of the birth of an active region.

Evolution of the two emerging flux areas image
Evolution of the two emerging flux areas in the emergence site of the active region. The left column shows the continuum intensity (at 525.043 nm) in the background with overlaid LOS velocity contours (red and blue correspond to redshifts and blueshifts, respectively). The middle column shows the evolution of the magnetic field, where the background is now the LOS magnetogram and the red lines show the transverse component of the magnetic field. In the right column, the LOS velocities after p-mode filtering are shown.

The Imaging Magnetograph Experiment (IMaX) recorded two small (~ 5'') emerging flux patches in the polarized filtergrams of a photospheric Fe I spectral line. Meanwhile, the Sunrise Filter Imager (SuFI) captured the highly dynamic chromospheric response to the magnetic fields pushing their way through the surface. The serendipitous capture of this event offers a closer look at the inner workings of active region emergence sites. In particular, it reveals in meticulous detail how the rising magnetic fields interact with the granulation as they push through the Sun's surface, dragging photospheric plasma in their upward travel. The plasma that is burdening the magnetic field slides along the field lines, creating fast downflowing channels at the footpoints.

The weight of this material anchors this field to the surface at semi-regular spatial intervals, preventing it from reaching the corona. Finally, magnetic reconnection enables the field to release from its photospheric anchors, allowing it to continue its voyage up to higher layers. This process releases energy that lights up the arch-filament systems and heats the surrounding chromosphere.

This manuscript was submitted to the Sunrise Special Issue of ApJ in July 2013.