The Spontaneous Genesis of Solar Prominence Structures Driven by Supergranulation in Three-Dimensional Simulations

TL;DR

This study addresses how quiescent solar prominences acquire their characteristic spine–feet–void morphology. It advances a three-dimensional magnetofrictional framework driven solely by photospheric supergranular flows to self-consistently form a mature magnetic flux rope that naturally develops spine, feet, and voids, without invoking parasitic polarities. The simulations reproduce key observational features from CHASE, NVST, and SDO, including the spine–feet geometry and inter-foot voids, and introduce the S-Z PIL rule linking initial filament clump formation to PIL topology and hemispheric chirality. The work highlights supergranulation as a primary helicity source shaping prominence structure and lays a foundation for future full MHD studies of fine-scale dynamics and stability in response to surface motions or distant eruptive events.

Abstract

Solar prominences usually have a horizontally elongated body with many feet extending to the solar surface, resembling a multi-arch bridge with many bridge piers. The basic mechanism by which solar prominences acquire these common structures during their evolution, however, remains an unresolved question. For the first time, our three-dimensional magneto-frictional simulation, driven by supergranular motions, self-consistently replicates the commonly observed multi-arch bridge morphology and its characteristic structures of solar quiescent prominences in a magnetic flux rope. In comparison with traditional views, our simulations demonstrate that the spine, feet, and voids (bubbles) are inherent prominence structures spontaneously forming as the flux rope evolves to a mature state. The voids mainly consist of legs of sheared magnetic loops caused by unbalanced supergranular flows, and prominence feet settle at the bottom of helical field lines piled up from the photosphere to the spine. Similarities between the simulated prominences and observed real prominences by the Chinese H$α$ Solar Explorer, the New Vacuum Solar Telescope, and NASA's Solar Dynamics Observatory suggest the high validity of our model. This work corroborates the pivotal role of photospheric supergranulation as a helicity injection source in the formation and shaping of quiescent prominence structures within the solar atmosphere, thereby paving a new avenue for future investigations into their fine dynamics and stability.

Figures (5)

• Figure 1: The formation of prominence spine, feet and voids. The left and right columns depict a time series of top-view (panels (a1) - (a5)) and side-view (panels (b1) - (b5)) images, respectively. The colored lumps represent dip regions at 1.0055-1.1 R$_\odot$, with saturation beyond 1.04 R$_\odot$. The white lines are magnetic field lines passing through the uniformly sampled points on the PILs of spheres at 1.005, 1.01, 1.015, 1.02, and 1.04 R$_\odot$. The black and white arrows indicate the shear pattern of the magnetic field lines. The red and blue boxes mark two types of void formation. Photospheric magnetograms and PILs are shown at the bottom. An animation of this figure is available (see the Supplementary Materials).
• Figure 2: The high-latitude prominence model from 1705-hour magnetofrictional simulation. (a), Isosurfaces representing magnetic dips are rendered using a rainbow color scheme, with colors mapped to the solar radius $r$. The red, yellow, and orange magnetic field lines pass through the spine, feet, and voids, respectively. The bottom photospheric boundary presents the white positive and black negative radial magnetic fluxes saturated at $\pm40$ G, the PILs in yellow, and horizontal supergranular flows in arrows near the MFR. (b), White lines depict the main body of the MFR, while red, yellow, and orange lines thread through the spine, feet, and voids, respectively. (c), Horizontal supergranular velocity vectors, colored by the divergence of velocity, with red indicating divergence and blue indicating convergence. In panels (d) - (f) with the same visualization in different viewing angles, the prominence is represented by magnetic field line segments within magnetic dip regions, field lines from the magnetic network are clipped beyond the transition region, resembling chromospheric fibrils, and all field lines are colored by $r$.
• Figure 3: Large-field-of-view H$\alpha$ images (a1) - (a3) from CHASE and high-resolution H$\alpha$ images (b1) - (b3) from NVST monitoring a quiescent prominence in a sequence of times and perspectives, with the dashed green boxes indicating the NVST field of view. The three dashed lines indicate the latitudes where feet are rooted, at $-15^\circ$, $-16.5^\circ$, and $-18^\circ$. The simulated prominence of the mid-latitude model at 1495 hr (c1) - (c3) is depicted from similar viewing angles as in (b1) - (b3). Red, yellow, and orange arrows indicate spines, feet, and voids in both the observed and the simulated filament. Isosurfaces depict magnetic dip regions of prominence from 1.0055 to 1.1 R$_\odot$, with height-indicating colors saturated at $1.04r_{\odot}$. The simulated photospheric magnetogram under the prominence is rendered in a grey scale.
• Figure 4: The growth and connection of filament segments. Panels (a1) - (a3) present a similar filament formation process above magnetograms in the mid-latitude numerical model with red isosurfaces depicting magnetic dip regions. H$\alpha$ images (b1) - (b3) illustrate a filament formation process observed by NVST. Yellow arrows indicate the initial four filament segments in (a1) and (b1). High-latitude models (c1) and (c2) at 450 hr present fragmented magnetic dip regions above the yellow Z-shape and S-shape PIL parts on the photospheric magnetograms in the southern and northern hemispheres, respectively. H$\alpha$ image d1 shows a short fragmented filament with sinistral chirality above Z-shape PIL parts in the southern hemisphere, while (d2) presents a forming filament with dextral chirality above S-shape PIL parts in the northern hemisphere. The white lines in panels (d1) and (d2) are the large-scale PILs at low coronal heights of the potential field extrapolated from the HMI magnetograms.
• Figure 5: Magnetic topology of spine, feet, and voids at 1705 hr in the high-latitude model. The volume rendering of the magnetic dip regions of the prominence has transparency to show the red, yellow, and orange magnetic field lines passing through the spine, feet, and voids, respectively, in the top views (left column, (a1) - (c1)) and the side views (right column, (a2) - (c2)). In panel (b1), the supergranular cells are described in blue. Panels (d1) - (d4) display particular magnetic field lines through the void and foot region. The white line indicates the reference line along which the magnetic field lines are sampled.