Charge Abundances of the Solar Wind Ions Inferred from Cometary X-Ray Spectra
Charge Abundances of the Solar Wind Ions Inferred from Cometary X-Ray Spectra
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从彗星 X 射线光谱推断太阳风离子的电荷丰度
DOI：
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发表时间：
2003
期刊：
影响因子：
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通讯作者：
V. Krasnopolsky
中科院分区：
文献类型：
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作者：
V. Kharchenko;Matthew Rigazio;A. Dalgarno;V. Krasnopolsky
钱德拉x射线望远镜探测到麦克诺特-哈特利彗星（C/1999 T1）的x射线发射光谱，假设它是由太阳风的重离子与彗星大气的原子和分子碰撞所捕获的电子产生的。通过与预测光谱的比较，得到了O+8和O+7离子相对丰度的准确值。O+8与O+7的丰度比为0.34±0.07，不确定度反映了测量统计量。对Ne+9离子捕获贡献的类似分析得出Ne+9与O+7的丰度比为0.02，不确定度为40%。光谱由许多未解析的谱线组成。最亮的特征主要由O+6在561 eV下的2 3S1→1 1S0自旋禁线和568 eV下的2 3P1→1 1S0互合线组成，其强度分别为74%和12%。与O+6谱线相比，O+7谱线中Lyα跃迁强度最强，为654 eV，强度为29%。研究了彗星x射线光谱对太阳风中高电荷氧离子丰度变化的敏感性。
An emission spectrum of X-rays from comet McNaught-Hartley (C/1999 T1) detected with the Chandra X-ray telescope is analyzed on the assumption that it results from electron captures by heavy ions of the solar wind colliding with the atoms and molecules of the cometary atmosphere. An accurate value of the relative abundance of O+8 and O+7 ions is obtained by comparing the spectrum derived from the measurement data with the predicted spectrum. A close match is found for an abundance ratio of O+8 to O+7 of 0.34 ± 0.07, the uncertainty reflecting the measurement statistics. A similar analysis of the contribution from captures by Ne+9 ions leads to an abundance ratio of Ne+9 to O+7 of 0.02 with an uncertainty of 40%. The spectrum consists of many unresolved lines. The brightest feature is composed mostly of the 2 3S1 → 1 1S0 spin-forbidden line of O+6 at 561 eV with 74% of the intensity and the 2 3P1 → 1 1S0 intercombination line at 568 eV with 12%. The strongest of the O+7 lines is the Lyα transition at 654 eV with an intensity of 29%, relative to the O+6 lines. The sensitivity of cometary X-ray spectra to variations in the abundances of highly charged oxygen ions in the solar wind is investigated.