  Three-dimensional magnetic nulls are the points where magnetic field vanishes
and are preferential sites for magnetic reconnection: a process which converts
magnetic energy into heat and accelerates charged particles along with a
rearrangement of magnetic field lines. In the solar corona, the reconnections
manifest as coronal transients including solar flares, coronal mass ejections
and coronal jets. The nulls are generally found to be collocated with complex
active regions on the solar photosphere. Extrapolation of magnetic field from
corresponding photospheric magnetogram indicate an abundance of these nulls in
solar atmosphere. Nevertheless, their generation is still not well understood.
Recently, Maurya et al. (2023) have demonstrated magnetic reconnection to be a
cause for generation and annihilation of magnetic nulls through
magnetohydrodynamics simulation, where the initial magnetic field is idealized
to have a single radial null. This article further extends the study in a more
realistic scenario where the initial magnetic field is constructed by
extrapolating photospheric magnetogram data and hence, incorporates field line
complexities inherent to a complex active region. For the purpose, the active
region NOAA 11977 hosting a C6.6 class flare is selected. The simulation is
initiated using non-force-free extrapolated magnetic field from the
photospheric vector magnetogram at around 02:48:00 UT on 17 February 2014, 16
minutes before the flare peak. The generation, annihilation and dynamics of
nulls are explored by a complimentary usage of trilinear null detection
technique and tracing of magnetic field line dynamics. It is found that the
nulls can spontaneously generate/annihilate in pairs while preserving the
topological degree and can have observational implications like footpoint
brightenings. Magnetic reconnection is found to be the cause of such generation
and annihilation.
