Solar chromospheric heating captured at sub-arcsec resolution

The solar chromosphere harbours small dynamic events which are associated with its heating. Our observations high resolution observations give a hint at a unified picture of magnetic heating in the solar atmosphere

October 24, 2018

By Smitha Narayanamurthy

The solar chromosphere harbours dynamic events such as the slender fibrils, compact ultraviolet bursts which are associated with its heating. High spatio-temporal resolution is required to capture the finer details of the likely magnetic reconnection-driven, rapidly evolving bursts. Such observations are also needed to reveal their similarities to large-scale flares, which are also thought to be reconnection driven, and more generally their role in chromospheric heating. During its second flight, SuFI onboard SUNRISE captured images of chromospheric heating in the form of a UV burst at a diffraction limited resolution of 0.1" at 7s cadence. The observed burst displayed a spatial morphology similar to that of a large-scale solar flare with a circular ribbon. The burst is composed of an extended ribbon-like feature and a rapidly evolving arcade of thin (∼0.1") magnetic loop-like features, similar to post-flare loops. Such a dynamic substructure reveals the small-scale nature of chromospheric heating in these bursts. Furthermore, based on magnetic field extrapolations, this heating event is associated with a complex fan-spine magnetic topology. Our observations strongly hint at a unified picture of magnetic heating in the solar atmosphere from some large-scale flares to small-scale bursts, all associated with such a magnetic topology. These results are published in Smitha H. N., Chitta L. P., Wiegelmann T., Solanki S. K. 2018, A&A, 617, A128. (ADS)

Left: image of the UV burst captured by SuFI. The contours enclose the regions of three different intensities in the ribbon-like feature, indicating the substructures within. The arrows point to loop-like features associated with the burst. Right: grayscale image is a sub-FOV of the IMaX line-of-sight magnetic field. Selected magnetic field extrapolations are plotted in blue (open/spine) and yellow (closed/dome) to show the complex fan-spine magnetic topology surrounding the burst.
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