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.

中文翻译：

---

太阳光球层中小型新兴双极子中解旋磁场的特征

我们使用太阳动力学天文台 (SDO) 上的日震和磁成像仪 (HMI) 进行的观测，对小型双极新兴通量区域内和周围的流体运动及其时间演变进行了研究。我们采用多普勒观测的局部相关跟踪来跟踪水平流体运动和视线磁力图来跟踪通量出现。垂直涡度和水平散度的变化用于推导出磁场中演化扭曲的特征。我们的分析表明，在磁通量出现的早期阶段，磁通量的两个极性在相反的方向上旋转，表明磁场中出现前的扭曲已经解开。我们进一步发现，在出现期间，相邻非磁性区域的漩涡运动增加。我们估算了磁能和动能，发现磁能大约是动能的 10 倍。在演化过程中，当磁能降低时，观察到动能增加，表明能量从磁通管的展开向周围流体运动转移。因此，我们的结果证明了新兴磁场中存在出现前扭曲，这在半球螺旋度规则的背景下很重要，需要在这种情况下进行详细的统计研究。此外，我们的观察表明，由于解旋磁场，可能会在新兴通量区域广泛产生扭转波，这对向上传输到日冕的能量有影响。