COMPOSITION AND SPECTRAL PROPERTIES OF THE 1 AU QUIET-TIME SUPRATHERMAL ION POPULATION DURING SOLAR CYCLE 23
COMPOSITION AND SPECTRAL PROPERTIES OF THE 1 AU QUIET-TIME SUPRATHERMAL ION POPULATION DURING SOLAR CYCLE 23
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太阳周期期间 1 天文单位安静时间超温离子群的组成和光谱特性 23
DOI：
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发表时间：
2008
期刊：
影响因子：
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通讯作者：
J. Mazur
中科院分区：
文献类型：
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作者：
M. Dayeh;M. Desai;J. Dwyer;H. Rassoul;G. Mason;J. Mazur
我们利用风/高能粒子：各向异性、组成和输运/超热穿能粒子望远镜和高级组成探测器/超低能同位素谱仪，在1995年1月1日至2007年12月31日的安静时间内，对能量在0.04至2.56 MeV核子-1之间的超热重离子的光谱和组成特性进行了调查。我们发现以下情况。(1)静止时间Fe/O和C/O丰度与太阳活动周期相关，反映了在太阳活动极大期太阳高能粒子和行星际（IP）激波事件中测得的相应值，以及在太阳活动极小期太阳风和共转相互作用区（CIR）中测得的相应值。(2)在1998-2004年的平静期，3 He/4 He比值在3%-8%的范围内，在27.4%的日子里检测到有限的3 He。在2005-2007年期间，这一比例下降到0.3%-1.2%，并且在0.5%的天中检测到有限的3 He。(3)所有的重离子都在0.04 ~ 0.32 MeV核子−1之间表现出超热尾，光谱指数在1.27 ~ 2.29之间。这些尾巴有时会延伸到102 MeV核子−1以上，而Fe的光谱会在比CNO更低的能量下翻转。(4)较重物种的超热尾光谱指数（即，比那些更轻的（即，Fe）更难。CNO）。这些指数没有表现出明显的太阳周期依赖性，并且在大约50%的时间内，它们显著偏离1.5的值。这些成分观测提供的证据表明，即使在IP空间中最安静的时候，超热人口（3 He和C-通过-Fe）由不同来源的离子组成，其相对贡献随太阳活动而变化。重离子的能谱表现出超热尾巴与可变的光谱指数，不表现出光谱指数为1.5的一些最近的模型预测。
We have surveyed the spectral and compositional properties of suprathermal heavy ions during quiet times from 1995 January 1 to 2007 December 31 using Wind/Energetic Particles: Anisotropy, Composition, and Transport/SupraThermal-through-Energetic Particle Telescope and Advanced Composition Explorer/Ultra-low Energy Isotope Spectrometer at energies between 0.04 and 2.56 MeV nucleon−1. We find the following. (1) Quiet-time Fe/O and C/O abundances are correlated with solar cycle activity, reflecting corresponding values measured in solar energetic particle and interplanetary (IP) shock events during solar maximum, and those measured in the solar wind and corotating interaction regions (CIRs) during solar minimum conditions. (2) The 3He/4He ratio lies in the 3%–8% range during the quiet times of 1998–2004 with finite 3He detected on ∼27.4% of the days. This ratio drops to 0.3%–1.2% during 2005–2007 and finite 3He is detected on ∼5% of the days. (3) All heavy-ion species exhibit suprathermal tails between 0.04 and 0.32 MeV nucleon−1 with spectral indices ranging from ∼1.27 to 2.29. These tails sometimes extend above ∼2 MeV nucleon−1 with Fe spectra rolling over at lower energies than those of CNO. (4) The suprathermal tail spectral indices of heavier species (i.e., Fe) are harder than those of the lighter ones (i.e., CNO). These indices do not exhibit a clear solar cycle dependence and for ∼50% of the time, they deviate significantly from the 1.5 value. These compositional observations provide evidence that even during the quietest times in IP space, the suprathermal population (3He and C-through-Fe) consists of ions from different sources whose relative contributions vary with solar activity. The heavy-ion energy spectra exhibit suprathermal tails with variable spectral indices that do not exhibit the spectral index of 1.5 predicted by some recent models.