Fig. 1.

Snapshots of the solar eruption observed by the Atmospheric Imaging Assembly (AIA). From left to right column, the images in a logarithmic scale show the solar lower chromosphere in 1600 Å, upper chromosphere and transition region in 304 Å, and corona in 131 Å. Pixel values, i.e, the CCD data number (DN), are scaled by the color bar for each individual image. a1 Is superimposed by the contours of the line-of-sight component of the photospheric magnetic field. A filament visible in 304 and 131 Å is located along the polarity inversion line, as marked by asterisks in a1, and its footpoints are marked by boxes. d3, e3 Are superimposed by contours of 6–12 and 25–50 keV sources at the levels of 50 and 80% of the maximum brightness, observed by the Reuven Ramaty High-Energy Solar Spectroscopic Imager (RHESSI). The hard X-ray sources are reconstructed with the CLEAN algorithm⁶⁷. The two feet of the magnetic flux rope (MFR) initially emerged as bright points (marked by arrows), with the western footpoint (FP−; d1–d3) appearing earlier than its eastern counterpart (FP+; e1–e3). An infant MFR formed at 13:39 UT in 131 Å, displaying in its eastern leg a fork-like feature that is anchored at FP+ e3