Paper: Prospective Implications of Extreme-ultraviolet Coronal Plumes for Magnetic-network Genesis of Coronal Heating, Coronal-hole Solar Wind, and Solar-wind Magnetic Field Switchbacks
Authors: Ronald L. Moore, Sanjiv K. Tiwari, Navdeep K. Panesar, Alphonse C. Sterling
Figure caption: Schematic vertical cross section for our conceptual magnetic field setup for an EUV plume (a) in a quasi-unipolar quiet region or (b) in a coronal hole. Both drawings are to scale, each spanning 130,000 km horizontally and vertically above the photosphere. The setup is depicted for when the polarity of the majority of the photospheric magnetic flux is positive. For simplicity, in this paper we define the transition region in this magnetic setup to be the plasma at temperatures from 104 K to 106 K in the magnetic funnels. Panel (a): Each minus sign marks a negative-polarity flux clump in a network cell interior between two contiguous funnel-ended far-reaching coronal loops. Each plus sign marks the positive-polarity network flux clump at the foot of a magnetic funnel. Each magnetic funnel and its coronal-loop extension are outlined by a pair of blue curves. The middle funnel is wider and is rooted in a clump of more and stronger positive flux than are the surrounding funnels that hem in the middle funnel. The middle funnel is the magnetic funnel of an EUV plume during the plume’s maximal luminosity in EUV plasma at hotter-transition-region and coronal temperatures around 106 K. The other magnetic funnels are nonplume funnels. Horizontal red dashed lines mark the (T = 104 K) top of the chromosphere between the feet of magnetic funnels. Short red arcs are chromospheric magnetic loops that connect network-cell-interior negative flux clumps to the closest edge of a funnel-foot flux clump. The horizontal green line low in each funnel marks the (T = 104 K) top of the chromosphere in the funnel. In the nonplume funnels, the horizontal purple line marks the (T = 106 K) top of the transition region and bottom of the corona. In the plume funnel, the purple line marks the height that the 106 K level had in that magnetic field before it coalesced to form the plume funnel. When an EUV plume is discernible in AIA coronal EUV images, its plasma at hotter-transition-region temperatures is striated and extends to heights of twice the plume’s width, as in Figure 2. TR stands for transition region. Panel (b): The magnetic setup and horizontal lines are the same as those in panel (a), except for two differences. One difference is that instead of being far-reaching closed coronal loops, the coronal extensions of the magnetic funnels are open; they extend out into the solar wind from the coronal hole. The other difference is that here the 106 K top of the transition region and bottom of the corona is 10 times higher than that in panel (a) for quasi-unipolar quiet regions. In the same way as in panel (a), the purple line in the plume funnel marks the 106 K height in the plume funnel’s magnetic field before it coalesced to form the plume funnel. As in Figure 2, during its maximal luminosity in emission from plasma at hotter-transition-region temperatures a coronal-hole plume is striated and extends to heights on the order of the 105 km height of the 106 K level in this schematic.