Comparison of Ion-Proton Differential Speed between ICMEs and Solar Wind near 1 au
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| Main Authors: | , , , , , , , , |
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| Format: | Preprint |
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2024
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| _version_ | 1866917655075618816 |
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| author | Zhang, Xuechao Song, Hongqiang Zhang, Chengxiao Fu, Hui Li, Leping Li, Jinrong Wang, Xiaoqian Wang, Rui Chen, Yao |
| author_facet | Zhang, Xuechao Song, Hongqiang Zhang, Chengxiao Fu, Hui Li, Leping Li, Jinrong Wang, Xiaoqian Wang, Rui Chen, Yao |
| contents | The elemental abundance of ICMEs and solar wind near 1 au is often adopted to represent the abundance in the corresponding coronal sources. However, the absolute abundance of heavy ions (relative to hydrogen) near 1 au might be different from the coronal abundance due to the ion-proton differential speed ($V_{ip}$). To illustrate the $V_{ip}$ characteristics and explore whether it influences the absolute abundance analysis for ICMEs and solar wind, we perform a statistical study on the $V_{ip}$ for He$^{2+}$, C$^{5+}$, O$^{6+}$, and Fe$^{10+}$ in both ICMEs and solar wind based on measurements of Advanced Composition Explorer. The results show that the $V_{ip}$ is negligible within ICMEs and slow solar wind ($<$ 400 km s$^{-1}$), while obvious in the intermediate (400 -- 600 km s$^{-1}$) and fast wind ($>$ 600 km s$^{-1}$). Previous studies showed that the $V_{ip}$ in ICMEs keeps negligible during propagation from 0.3 to 5 au, but in solar wind it increases with the decreasing heliocentric distance. Therefore, it might be questionable to infer the absolute abundance of coronal sources through in-situ abundance near 1 au for solar wind. Fortunately, the ion-oxygen (O$^{6+}$) differential speed ($V_{io}$) is negligible for He$^{2+}$, C$^{5+}$, and Fe$^{10+}$ within both ICMEs and solar wind, and previous studies suggested that the $V_{io}$ does not vary significantly with the heliocentric distance. This indicates that various heavy ions always flow at the same bulk speed and their relative abundance (relative to oxygen) near 1 au can represent the coronal abundance for both ICMEs and solar wind. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2405_00336 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Comparison of Ion-Proton Differential Speed between ICMEs and Solar Wind near 1 au Zhang, Xuechao Song, Hongqiang Zhang, Chengxiao Fu, Hui Li, Leping Li, Jinrong Wang, Xiaoqian Wang, Rui Chen, Yao Solar and Stellar Astrophysics Space Physics The elemental abundance of ICMEs and solar wind near 1 au is often adopted to represent the abundance in the corresponding coronal sources. However, the absolute abundance of heavy ions (relative to hydrogen) near 1 au might be different from the coronal abundance due to the ion-proton differential speed ($V_{ip}$). To illustrate the $V_{ip}$ characteristics and explore whether it influences the absolute abundance analysis for ICMEs and solar wind, we perform a statistical study on the $V_{ip}$ for He$^{2+}$, C$^{5+}$, O$^{6+}$, and Fe$^{10+}$ in both ICMEs and solar wind based on measurements of Advanced Composition Explorer. The results show that the $V_{ip}$ is negligible within ICMEs and slow solar wind ($<$ 400 km s$^{-1}$), while obvious in the intermediate (400 -- 600 km s$^{-1}$) and fast wind ($>$ 600 km s$^{-1}$). Previous studies showed that the $V_{ip}$ in ICMEs keeps negligible during propagation from 0.3 to 5 au, but in solar wind it increases with the decreasing heliocentric distance. Therefore, it might be questionable to infer the absolute abundance of coronal sources through in-situ abundance near 1 au for solar wind. Fortunately, the ion-oxygen (O$^{6+}$) differential speed ($V_{io}$) is negligible for He$^{2+}$, C$^{5+}$, and Fe$^{10+}$ within both ICMEs and solar wind, and previous studies suggested that the $V_{io}$ does not vary significantly with the heliocentric distance. This indicates that various heavy ions always flow at the same bulk speed and their relative abundance (relative to oxygen) near 1 au can represent the coronal abundance for both ICMEs and solar wind. |
| title | Comparison of Ion-Proton Differential Speed between ICMEs and Solar Wind near 1 au |
| topic | Solar and Stellar Astrophysics Space Physics |
| url | https://arxiv.org/abs/2405.00336 |