论文标题
主动区域的非中和电流被解释为投影效应
Non-Neutralized Electric Current of Active Regions Explained as a Projection Effect
论文作者
论文摘要
活动区域（ARS）通常具有单个磁性极性中观察到的净电流。我们表明，当扭曲的通量管倾斜地与光球相交时，这种“非中和”电流可能是由几何投影效应引起的。为此，我们通过在各个高度的半侧磁管的水平切片中采样水平切片来模拟新出现的AR的表面图。尽管管子没有净环形电流，但沿垂直方向投射时，其poloidal电流在表面上相当于明显的非中和分量。如果管仅像在逼真的设置中部分出现，则非中和电流将1）在剪切极性反转线附近作为双丝带发育，（2）与扭曲呈正相关，而3）在磁磁通前达到了最大值。投影效应对光球电流分布可能很重要，尤其是在磁通出现的早期阶段。
Active regions (ARs) often possess an observed net electric current in a single magnetic polarity. We show that such "non-neutralized" currents can arise from a geometric projection effect when a twisted flux tube obliquely intersects the photosphere. To this end, we emulate surface maps of an emerging AR by sampling horizontal slices of a semi-torus flux tube at various heights. Although the tube has no net toroidal current, its poloidal current, when projected along the vertical direction, amounts to a significant non-neutralized component on the surface. If the tube emerges only partially as in realistic settings, the non-neutralized current will 1) develop as double ribbons near the sheared polarity inversion line, (2) positively correlate with the twist, and 3) reach its maximum before the magnetic flux. The projection effect may be important to the photospheric current distribution, in particular during the early stages of flux emergence.
