Magnetic braking of the present Sun
Magnetic braking of the present Sun
复制标题
当前太阳的磁制动
DOI：
10.1046/j.1365-8711.1999.02134.x
复制
发表时间：
1999
影响因子：
4.8
通讯作者：
Jianke Li
中科院分区：
文献类型：
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作者：
Jianke Li
磁制动对于具有对流包层的晚型恒星的角动量传输至关重要。该机制可能完全负责目前太阳的缓慢旋转，制动模型通常被校准。最近或目前的卫星任务，如太阳神和太阳能卫星，共同揭示了一个更完整的太阳日冕，更具体的太阳风的图片。在太阳活动极小期或接近极小期时，这些丰富的数据对于约束偶极太阳制动模型是有价值的。在本文中，我们使用最近可用的观测（在或接近太阳极小期），以约束太阳磁制动模型的基础上的偶极场结构。结果表明，在高纬度地区，ONEX资料显示出一个球形的阿尔芬面。我们推断，从热风模型，它位于16 Ro stec，这是大于12 Rodot;推导出太阳能最低点附近的赤道地区的太阳神数据。它也被发现，制动模型与从偶极子到分裂的双极场的过渡一般是一致的双极观测，只要死区范围和偶极子场强之间的线性关系是满意的。因此，偶极场保留了相当大的死区，但比标准值强得多，或者场具有标准强度，但死区非常小（<2 R x steco）。由实验数据得到的磁制动率为2.1× 1030达因·厘米，约为Weber & Davis模型的四分之一，与Pizzo等人的结果相差不大。
Magnetic braking is essential for angular momentum transport in late-type stars which have convective envelopes. The mechanism may be entirely responsible for the slow rotation of the present Sun, on which a braking model is normally calibrated. Recent or current satellite missions such as Helios and Ulysses have jointly revealed a more complete picture of the solar corona, and more specifically of the solar wind. The wealth of these data at or near the solar minimum is valuable for constraining the dipolar solar braking model. In this paper, we use recently available observations (at or near the solar minimum) to constrain a solar magnetic braking model based on a dipolar field structure. It is found that the Ulysses data indicate a spherical Alfven surface at high latitudes. We infer from a thermal wind model that it is located at 16 Ro˙, which is larger than the 12 Rodot; deduced from the Helios data for the equatorial region near the solar minimum. It is also found that the braking model with a transition from a dipole to a split monopole field is generally consistent with Ulysses observations, provided that a linear relation between dead zone extent and dipole field strength is satisfied. Thus either the dipole field retains a sizeable dead zone but is much stronger than the standard value, ∼ 1 G, or the field has standard strength but an exceedingly small dead zone (<2 R x o˙). The magnetic braking rate as constrained by Ulysses data is found to be 2.1× 1030 dyn cm, which is about a quarter of the value deduced earlier from the Weber & Davis model and does not differ significantly from that deduced by Pizzo et al.
H.Washimi：“包括太阳自转效应在内的太阳风的模拟研究”太阳物理。
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