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ENERGY SPECTRA OF IONS ACCELERATED IN IMPULSIVE AND GRADUAL SOLAR EVENTS

机译:脉冲和梯度太阳能事件中加速的离子能谱

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We report new high-sensitivity measurements of the energy spectra of ions from five impulsive solar flares and one gradual event observed during solar minimum by the Energetic Particles, Acceleration, Composition, and Transport (EPACT) experiment aboard the WIND spacecraft. All of the impulsive-flare events had intensities too low to be visible on previous spacecraft such as ISEE 3, which observed hundreds of impulsive-flare events. Often these events cluster in or behind a coronal mass ejection (CME) where magnetic field lines provide an excellent connection to a solar active region where flares are occurring. In most cases we can see velocity dispersion as the ions of 20 keV amu~(-1) to 10 MeV amu~(-1) streamed out from the impulsive flare at the Sun, arriving in inverse order of their velocity. Ions from a large, magnetically well-connected gradual event, associated with a CME-driven shock, also show velocity dispersion early in the event but show identical time profiles that last for several days late in the event. These time-invariant spectra of H, ~4He, C, O, and Fe in this gradual event are well represented as power laws in energy from 20 keV amu~(-1) to ~100 MeV amu~(-1). In the impulsive-flare events, H, ~3He, ~4He, C, O, and Fe have more rounded spectra that flatten somewhat at low energies; yet the intensities continue to increase down to 20 keV amu~(-1). Most of the ion energy content appears to lie below 1 MeV in the impulsive events, where it would be invisible to γ-ray line observations.
机译:我们报告了WIND航天器上的高能粒子,加速,组成和输运(EPACT)实验,对来自五个脉冲太阳耀斑和一个太阳逐渐最小期间观测到的一个渐进事件的离子的能谱进行了新的高灵敏度测量。所有冲动耀斑事件的强度都太低,无法在以前的航天器(例如ISEE 3)上看到,该航天器观测到数百次冲动耀斑事件。通常,这些事件聚集在日冕物质抛射(CME)中或冠状物质抛射(CME)后面,其中磁力线提供了与发生耀斑的太阳活动区域的良好连接。在大多数情况下,我们可以看到速度弥散,即20 keV amu〜(-1)到10 MeV amu〜(-1)的离子从太阳的脉冲耀斑中流出,其速度成反比。与CME驱动的冲击相关的大型,磁性良好的渐进事件产生的离子,在事件开始时也显示出速度分散,但显示出相同的时间曲线,并持续了几天。这些逐渐变化的H,〜4He,C,O和Fe的时不变谱很好地表示为从20 keV amu〜(-1)到〜100 MeV amu〜(-1)的能量幂律。在脉冲耀斑事件中,H,〜3He,〜4He,C,O和Fe具有更圆的光谱,在低能量下会变平。但是强度继续降低到20 keV amu〜(-1)。在脉冲事件中,大多数离子能量含量似乎都低于1 MeV,这在γ射线线观察中是不可见的。

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