SPECTRAL PROPERTIES OF LARGE GRADUAL SOLAR ENERGETIC PARTICLE EVENTS. I. FE, O, AND SEED MATERIAL
SPECTRAL PROPERTIES OF LARGE GRADUAL SOLAR ENERGETIC PARTICLE EVENTS. I. FE, O, AND SEED MATERIAL
复制标题
DOI：
10.3847/0004-637x/816/2/68
复制
发表时间：
2016-01-10
影响因子：
4.9
通讯作者：
Smith, C. W.
中科院分区：
文献类型：
--
作者：
Desai, M. I.;Mason, G. M.;Smith, C. W.
我们调查了在太阳周期23和24期间在ACE观测到的46个孤立的、大的渐进SEP事件中类似于0.1-100 MeV的核子（-1）O和Fe的影响光谱。大多数SEP光谱可以用归一化常数、低能谱斜率、高能谱斜率和破碎能的四参数带函数很好地表示。O和Fe的光谱斜率相似，大多数光谱在断裂能以上变陡，可能是由于影响不同离子种类的共同加速和输运过程。断裂能以上的SEP谱取决于种子种群的来源；超热耀斑物质的贡献越大，能量越高，Fe/O比值越高，光谱越平坦。具有较陡的低能和较高的破裂能的SEP事件与较慢的日冕物质抛射（cme）有关，而与快速（>2000 km s(-1)） cme和地面增强相关的SEP事件在低能和高能具有较硬或较平坦的光谱，并且O破裂能在类似于1和10 MeV的核子（-1）之间。后一种事件富含He-3和高能量的Fe，并且具有明显低于O的能量翻转的Fe谱，这可能是因为较小Q/M比的Fe离子比较大Q/M比的O离子更容易从远处激波中逃脱。我们得出结论，SEP光谱特性是由许多复杂和相互竞争的影响造成的，即依赖于Q/ m的散射、激波特性和种子种群的起源，所有这些都必须考虑在内，才能全面了解cme驱动的大型渐进SEP事件的激波加速度。
We have surveyed similar to 0.1-100 MeV nucleon(-1) O and Fe fluence spectra during 46 isolated, large gradual SEP events observed at ACE during solar cycles 23 and 24. Most SEP spectra are well represented by the four-parameter Band function with a normalization constant, low-energy spectral slope, high-energy spectral slope, and break energy. The O and Fe spectral slopes are similar and most spectra steepen above the break energy, probably due to common acceleration and transport processes affecting different ion species. SEP spectra above the break energies depend on the origin of the seed population; larger contributions of suprathermal flare material result in higher Fe/O ratios and flatter spectra at higher energies. SEP events with steeper O spectra at low energies and higher break energies are associated with slower coronal mass ejections (CMEs), while those associated with fast (>2000 km s(-1)) CMEs and ground level enhancements have harder or flatter spectra at low and high energies, and O break energies between similar to 1 and 10 MeV nucleon(-1). The latter events are enriched in He-3 and higher-energy Fe, and have Fe spectra that rollover at significantly lower energies compared with O, probably because Fe ions with smaller Q/M ratios can escape from the distant shock more easily than O ions with larger Q/M ratios. We conclude that SEP spectral properties result from many complex and competing effects, namely Q/M-dependent scattering, shock properties, and the origin of the seed populations, all of which must be taken into account to develop a comprehensive picture of CME-driven shock acceleration of large gradual SEP events.