在太阳X射线喷射中发现阿尔夫文波的证据
J W Cirtain1, L Golub, L Lundquist
1Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA. Jonathan.W.Cirtain@nasa.gov
概括
新的观测揭示了许多来自极地冠状孔的高速X射线喷射. 这些频繁发生的动态事件可能会对高速太阳风产生重大影响.
科学领域:
- 太阳物理 太阳物理
- 等离子体天体物理学
- 太空天气 太空天气
背景情况:
- 冠状磁场是高度动态的,经历了磁再连接等过程.
- 磁再连接可以释放大量的能量,导致诸如太阳耀斑,冠状质量喷射和较小规模的X射线喷射等现象.
- 之前对X射线喷射的观察记录了较低的事件速率和速度.
研究的目的:
- 为了研究极地冠状孔中的X射线喷射的特征和频率.
- 为了确定这些观测到的X射线喷射的速度和尺寸.
- 评估X射线喷射对太阳风的潜在贡献.
主要方法:
- 利用了Hinode对极地冠状孔的观测.
- 检测和分析了X射线喷射事件.
- 测量喷气速度,尺寸和持续时间.
主要成果:
- 发现了两种不同速度的X射线喷射:阿尔夫文附近的速度 (~800公里/秒) 和接近声速的速度 (200公里/秒).
- 观察到与以前的报告相比,事件的频率明显增加,平均每小时发生10次.
- 喷射的特征是2 x 10^3到2 x 10^4公里宽,1 x 10^5公里长,持续时间为100-2500秒.
结论:
- 高数量和X射线喷射的速度表明它们是一个常见的和充满活力的现象.
- 这些发现表明,X射线喷射可能在加速和促进高速太阳风方面发挥着至关重要的作用.
- 需要进一步的研究才能充分理解这些喷射对太阳风动力学和太空天气的影响.
相关概念视频
X-ray Imaging
German physicist Wilhelm Röntgen (1845–1923) was experimenting with electrical current when he discovered that a mysterious and invisible "ray" would pass through his flesh but leave an outline of his bones on a screen coated with a metal compound. In 1895, Röntgen made the first durable record of the internal parts of a living human: an "X-ray" image (as it came to be called) of his wife’s hand. Scientists worldwide quickly began their own experiments with X-rays, and by 1900, X-ray was widely...
Atomic Emission Spectroscopy: Overview
Atomic emission spectroscopy (AES) is an analytical technique used to determine the elemental composition of a sample by analyzing the light emitted from excited atoms. In AES, atoms in a sample are excited to higher energy levels by thermal energy from high-temperature sources, such as plasma, arcs, or sparks. When these excited atoms return to lower energy states, they emit light at specific wavelengths characteristic of each element. The resulting atomic emission spectrum, which consists of...
Atomic Emission Spectroscopy: Interference
In atomic emission spectroscopy (AES), high-temperature atomizers excite a broad range of elements and molecules that generate complex emissions from sources such as oxides, hydroxides, and flame combustion products in the flame or plasma. Several strategies can be employed to minimize spectral interferences caused by overlapping emission lines or bands. These include increasing instrument resolution, choosing alternative emission lines, optimally placing the detector in low-background regions,...
The de Broglie Wavelength
In the macroscopic world, objects that are large enough to be seen by the naked eye follow the rules of classical physics. A billiard ball moving on a table will behave like a particle; it will continue traveling in a straight line unless it collides with another ball, or it is acted on by some other force, such as friction. The ball has a well-defined position and velocity or well-defined momentum, p = mv, which is defined by mass m and velocity v at any given moment. This is the typical...
Plane Electromagnetic Waves II
Consider a plane wavefront traveling in position x-direction with a constant speed. This wavefront can be utilized to obtain the relationship between electric and magnetic fields with the help of Faraday's law.
Energy Carried By Electromagnetic Waves
Anyone who has used a microwave oven knows there is energy in electromagnetic waves. Sometimes, this energy is obvious, such as in the summer sun's warmth. At other times, it is subtle, such as the unfelt energy of gamma rays, which can destroy living cells. Electromagnetic waves bring energy into a system through their electric and magnetic fields. These fields can exert forces and move charges in the system and, thus, do work on them. However, there is energy in an electromagnetic wave,...


