SH024-0003
Plumelets: Dynamic Filamentary Structures in Solar Plumes
Plumelets: Dynamic Filamentary Structures in Solar Plumes
Thursday, 10 December 2020
Poster
Abstract:
Solar plumes long seemed to possess a simple geometry supporting spatially coherent,
stable outflow without significant fine structure. Recent high-resolution observations have
challenged this picture by revealing numerous transient, small-scale, collimated outflows
(“jetlets”) at the base of plumes (see Kumar et al. presentation in this session). The dynamic filamentary structure of solar plumes above
these outflows, and its relationship with the overall plume structure, have remained largely
unexplored. We report a statistical analysis of continuously observed fine structure inside
a bright plume within a mid-latitude coronal hole during 2016 July 2-3. By applying advanced
edge-enhancement and spatiotemporal analysis techniques to extended series of highresolution
images from the Solar Dynamics Observatory’s Atmospheric Imaging Assembly,
we determined that the plume was composed of numerous time-evolving bright filamentary
substructures, referred to as “plumelets” in this paper, that accounted for most of the
plume emission. The number of simultaneously identifiable plumelets varied over the observation
period, was positively correlated with plume brightness, and peaked in the fully
formed plume. The plumelets had transverse widths of 10 Mm and intermittently supported
upwardly propagating periodic disturbances with phase speeds of 190-260 km s-1 and longitudinal
wavelengths of 55-65 Mm. The characteristic frequency (3.5 mHz) is commensurate
with that of solar p-modes. Oscillations in neighboring plumelets are uncorrelated, indicating
that the waves could be driven by p-mode flows at spatial scales smaller than the plumelet
separation. Multiple independent sources of outflow within a single coronal plume should impart
significant fine structure to the fast solar wind and be detectable by Parker Solar Probe
at perihelion.
stable outflow without significant fine structure. Recent high-resolution observations have
challenged this picture by revealing numerous transient, small-scale, collimated outflows
(“jetlets”) at the base of plumes (see Kumar et al. presentation in this session). The dynamic filamentary structure of solar plumes above
these outflows, and its relationship with the overall plume structure, have remained largely
unexplored. We report a statistical analysis of continuously observed fine structure inside
a bright plume within a mid-latitude coronal hole during 2016 July 2-3. By applying advanced
edge-enhancement and spatiotemporal analysis techniques to extended series of highresolution
images from the Solar Dynamics Observatory’s Atmospheric Imaging Assembly,
we determined that the plume was composed of numerous time-evolving bright filamentary
substructures, referred to as “plumelets” in this paper, that accounted for most of the
plume emission. The number of simultaneously identifiable plumelets varied over the observation
period, was positively correlated with plume brightness, and peaked in the fully
formed plume. The plumelets had transverse widths of 10 Mm and intermittently supported
upwardly propagating periodic disturbances with phase speeds of 190-260 km s-1 and longitudinal
wavelengths of 55-65 Mm. The characteristic frequency (3.5 mHz) is commensurate
with that of solar p-modes. Oscillations in neighboring plumelets are uncorrelated, indicating
that the waves could be driven by p-mode flows at spatial scales smaller than the plumelet
separation. Multiple independent sources of outflow within a single coronal plume should impart
significant fine structure to the fast solar wind and be detectable by Parker Solar Probe
at perihelion.