  We perform a study of fluid motions and its temporal evolution in and around
a small bipolar emerging flux region using observations made by the
Helioseismic and Magnetic Imager (HMI) on-board the Solar Dynamics Observatory
(SDO). We employ local correlation tracking of the Doppler observations to
follow horizontal fluid motions and line-of-sight magnetograms to follow the
flux emergence. Changes in vertical vorticity and horizontal divergence are
used to derive signatures of evolving twists in the magnetic field. Our
analysis reveals that the two polarities of the magnetic flux swirl in opposite
directions in early stages of flux emergence indicating an unwinding of the
pre-emergence twists in the magnetic field. We further find that during the
emergence, there is an increase in swirly motions in the neighbouring
non-magnetic regions. We estimate the magnetic and kinetic energies and find
that magnetic energy is about a factor of ten larger than the kinetic energy.
During the evolution, when the magnetic energy decreases, an increase in the
kinetic energy is observed indicating transfer of energy from the unwinding of
magnetic flux tube to the surrounding fluid motions. Our results thus
demonstrate the presence of pre-emergence twists in emerging magnetic field
that is important in the context of the hemispheric helicity rule warranting a
detailed statistical study in this context. Further, our observations point to
a possible widespread generation of torsional waves in emerging flux regions
due to the untwisting magnetic field with implications for upward energy
transport to the corona.

Solar and Stellar Astrophysics