太阳光球磁亮点的识别

发布时间：2018-04-30 20:05

本文选题：太阳光球 + 磁亮点　；参考：《中国科学院研究生院（云南天文台）》2013年硕士论文

【摘要】：在太阳光球表面出现的磁亮点是目前的观测手段能够分辨的最小磁结构，也被认为是日冕磁场在光球的足点运动的可靠的示踪者，其运动所耗散的能量被认为是日冕加热和色球加热的最终能量来源之一。在其运动过程中，高密度的光球物质带着磁场一起运动，在色球和日冕磁场当中产生波动或者扭绞将光球物质的动能传送到色球和日冕。为了解开日冕加热和色球加热等世纪未解之谜，对磁亮点的研究就显示出了它特殊的重要性。关于磁亮点的形成原理，很多科学家都认为是在磁通量管的对流塌缩过程中形成的。也有很多观测方面和数值模拟方面的研究结果重现了对流塌缩过程，确认了磁亮点确实是在对流塌缩过程中形成的。即对流塌缩的过程是先有强的等离子体流下沉，磁场强度增强，，最后磁亮点出现。一些数值模拟和观测的结果发现，在对流塌缩过程中，当强的等离子体流下沉到密度较大的磁通量管底部时会发生较强的反弹上升现象。而这个上升的等离子体流会形成激波上升至日冕形成针状体。与此同时，在磁通量管底部的等离子体反弹上升的过程中，磁通量管温度上升，磁场强度减小，最后导致磁通量管破裂。这是磁通量管的另一种不稳定性。理论研究发现，当磁环在光球上的足点以1-2km s~(-1)运动时，足点所在的磁通量管产生振荡并激发阿尔芬波。阿尔芬波在光球中被激发，然后向上传播到色球和日冕层，并在色球和日冕层中消耗掉能量以加热色球和日冕。不过，阿尔芬波还没有在光球层检测出来。光球上的足点是否有1-2km s~(-1)大小的运动速度是研究光球磁通量管能否通过振荡产生阿尔芬波的一个关键因素。磁亮点的尺度在100-200公里之间，磁亮点的亮度是光球平均亮度的2-4倍。磁亮点的运动速度平均在1-2公里/秒。也有少数磁亮点运动速度较快，达到3-4公里/秒。研究发现有一些磁亮点沿着对数螺线方式进行涡旋运动。磁亮点的寿命从几十秒到几十分钟不等。亮度较大，尺度较大的磁亮点的寿命较长。对磁亮点的研究基于准确的识别方法。我们运用区域生长法对磁亮点进行识别，并给出了识别的结果。
[Abstract]:The magnetic bright spot on the surface of the solar sphere is the least magnetic structure that can be distinguished by current observation methods, and is also considered to be a reliable tracer of the coronal magnetic field moving at the foot of the photosphere. The energy dissipated by its motion is considered to be one of the final sources of energy for coronal heating and chromosphere heating. In the course of its motion, the high-density light-ball material moves with a magnetic field and waves in the chromosphere and the coronal magnetic field, or twists the kinetic energy of the light-ball matter to the chromosphere and the corona. In order to solve the unsolved mystery of coronal heating and chromosphere heating, the study of magnetic highlights shows its special importance. Many scientists believe that the formation of magnetic bright spots is due to the convection collapse of magnetic flux tubes. There are also many observations and numerical simulation results to reproduce the convection collapse process, which confirms that the magnetic bright spot is really formed in the convection collapse process. The process of convection collapse is that there is a strong plasma flow sinking, the magnetic field intensity is enhanced, and finally the magnetic bright spot appears. Some numerical simulations and observations show that a strong rebound and rise will occur when a strong plasma flows down to the bottom of a dense magnetic flux tube during convection collapse. This rising plasma stream forms shock waves that rise to the corona to form acicular bodies. At the same time, in the process of plasma rebound and rising at the bottom of the flux tube, the temperature of the flux tube increases and the magnetic field intensity decreases, which finally leads to the rupture of the flux tube. This is another instability of the flux tube. Theoretically, it is found that the flux tube in which the magnetic foot is located oscillates and excites the Alfen wave when the step of the magnetic ring moves in the 1-2km squi-1). Alfven wave is excited in the sphere of light and then propagates upward to the chromosphere and the coronal layer and consumes energy in the chromosphere and coronal layer to heat the chromosphere and corona. However, Alfven wave has not been detected in the photosphere. It is a key factor to study whether the spheroidal flux tube can produce the Alfen wave by oscillating or not. The magnetic bright spots range from 100 km to 200 km, and the brightness of the magnetic bright spots is 2-4 times that of the average luminous sphere. The average velocity of the magnetic spot is 1-2 km / s. There are also a few magnetic highlights moving faster, up to 3-4 km / s. It is found that there are some magnetic highlights moving along the logarithmic spiral. Magnetic highlights range in life from tens of seconds to tens of minutes. The lifetime of magnetic bright spots with higher brightness and larger scale is longer. The study of magnetic highlights is based on accurate recognition methods. The region growth method is used to identify the magnetic highlights, and the recognition results are given.
【学位授予单位】：中国科学院研究生院（云南天文台）
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：P182.4

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