93 research outputs found
Dynamics of the Transition corona
Magnetic reconnection between open and closed magnetic field in the corona is
believed to play a crucial role in the corona/heliosphere coupling. At large
scale, the exchange of open/closed connectivity is expected to occur in
pseudo-streamer structures. However, there is neither clear observational
evidence of how such coupling occurs in pseudo-streamers, nor evidence for how
the magnetic reconnection evolves. Using a newly-developed technique, we
enhance the off-limb magnetic fine structures observed with AIA and identify a
pseudo-streamer-like feature located close to the northern coronal hole. After
extrapolating the magnetic field with the PFSS model, we obtain a
pseudo-streamer magnetic topology, null-point related topology bounded by open
field. We compare the magnetic configuration with the UV observations and
identify the magnetic structures expected to be involved in the event. Using an
3D MHD simulation of interchange reconnection, we showed that the evolution of
the UV structures follows the magnetic field dynamics and the UV emitting
structures have a pattern very similar to the plasma emission derived from the
simulation. Our results highlight that the exchange between open and closed in
the pseudo-streamer topology related to an observed event occurs at least
partially at the null-point, similarly to the interchange reconnection in a
single null-point topology. However, our results also indicate that the
interchange reconnection in pseudo-streamers is a gradual physical process
which opposes to the impulsive reconnection of the solar-jet model
Complex Dynamic Flows in Solar Flare Sheet Structures
Observations of high-energy emission from solar flares often reveal the presence of large sheet-like structures, sometimes extending over a space comparable to the Sun's radius. Given that these structures are found between a departing coronal mass ejection and the post-eruption flare arcade, it is natural to associate the structure with a current sheet; though the relationship is unclear. Moreover, recent high-resolution observations have begun to reveal that the motions in this region are highly complex, including reconnection outflows, oscillations, and apparent wakes and eddies. We present a detailed first look at the complicated dynamics within this supra-arcade plasma, and consider implications for the interrelationship between the plasma and its embedded magnetic field
- …