New Delhi: Astronomers have captured unprecedented, detailed views of a powerful solar eruption that stalled and collapsed back into the Sun. The intense
solar flare occurred in March 2024, within a large, magnetically complex active region or cluster of sunspots, lifting a prominence of relatively cool, dense gas suspended above the solar surface. The material was held in place by twisting magnetic fields, and was expected to break free in the form of a coronal mass ejection (CME). Instead, the eruption abruptly slowed down and halted, with the suspended plasma plunging back down towards the surface.
While failed eruptions have been documented extensively, the mechanisms behind them have remained poorly understood. Researchers gained valuable insights into the underlying processes by using data from multiple spacecraft, including NASA’s Solar Dynamics Observatory, the Hinode satellite, the Solar Orbiter of the European Space Agency (ESA) and a number of ground-based astronomical instruments. This multi-angle, multi-wavelength approach allowed the team to track both hot, X-ray emitting plasma and cooler prominence material simultaneously, mapping these movements directly to underlying tangled magnetic fields. The data revealed that the magnetic field lines were breaking and re-joining at two separate sites concurrently.
Magnetic Reconnection Events are the key
Below the rising structure, a standard magnetic reconnection pushed the eruption outward. Crucially, a second reconnection process occurred simultaneously above the structure, cutting into the top of the erupting magnetic loop, and weakening the forces driving the material upward and outward. At the same time, exceptionally strong overlying magnetic fields acted as a cage, decaying too slowly to allow the eruption to escape the solar atmosphere. The combination of internal erosion from above, and strict confinement from outside ultimately ended up aborting the eruption. These findings solve a long-standing puzzle on why other Sun-like stars exhibit numerous flares, but very few visible CMEs. A paper describing the research has been published in Nature.
