Parameter effects on the total intensity of H I Lyα line for a modelled coronal mass ejection and its driven shock
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2024
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| _version_ | 1866916307011633152 |
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| author | Ying, Beili Shi, Guanglu Feng, Li Lu, Lei Xue, Jianchao Li, Shuting Gan, Weiqun Li, Hui |
| author_facet | Ying, Beili Shi, Guanglu Feng, Li Lu, Lei Xue, Jianchao Li, Shuting Gan, Weiqun Li, Hui |
| contents | The combination of the H I Lyα (121.6 nm) line formation mechanism with ultraviolet (UV) Lyα and white-light (WL) observations provides an effective method for determining the electron temperature of coronal mass ejections (CMEs). A key to ensuring the accuracy of this diagnostic technique is the precise calculation of theoretical Lyα intensities. This study performs a modelled CME and its driven shock via the 3D MHD simulation. We generate synthetic UV and WL images of the CME and shock to quantify the impact of different assumptions on theoretical Lyα intensities, such as the incident intensity of the Lyα line (Idisk), the geometric scattering function (p(θ)), and the kinetic temperature (Tn) assumed to be equal to the proton (Tp) or electron (Te) temperatures. By comparing differences of the Lyα intensities under these assumptions, we find that: (1) Using the uniform or Carrington maps of the disk Lyα emission underestimates the corona Lyα intensity (< 10%) compared to the synchronic map, except for a slight overestimate (< 4%) in the partial CME core. The Carrington map yields lower uncertainties than the uniform disk. (2) The geometric scattering process has a minor impact on the Lyα intensity, with a maximum relative uncertainty of < 5%. The Lyα intensity is underestimated for the most part but overestimated in the CME core. (3) Compared to the assumption Tn = Tp, using Tn = Te leads to more complex relative uncertainties in CME Lyα intensity. The CME core and void are both overestimated, with the maximum uncertainty in the core exceeding 50% and the void remaining below 35%. In the CME front, both over- and under-estimates exist with relative uncertainties of < 35%. The electron temperature assumption has a smaller impact on the shock, with an underestimated relative uncertainty of less than 20%. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2406_11297 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Parameter effects on the total intensity of H I Lyα line for a modelled coronal mass ejection and its driven shock Ying, Beili Shi, Guanglu Feng, Li Lu, Lei Xue, Jianchao Li, Shuting Gan, Weiqun Li, Hui Solar and Stellar Astrophysics The combination of the H I Lyα (121.6 nm) line formation mechanism with ultraviolet (UV) Lyα and white-light (WL) observations provides an effective method for determining the electron temperature of coronal mass ejections (CMEs). A key to ensuring the accuracy of this diagnostic technique is the precise calculation of theoretical Lyα intensities. This study performs a modelled CME and its driven shock via the 3D MHD simulation. We generate synthetic UV and WL images of the CME and shock to quantify the impact of different assumptions on theoretical Lyα intensities, such as the incident intensity of the Lyα line (Idisk), the geometric scattering function (p(θ)), and the kinetic temperature (Tn) assumed to be equal to the proton (Tp) or electron (Te) temperatures. By comparing differences of the Lyα intensities under these assumptions, we find that: (1) Using the uniform or Carrington maps of the disk Lyα emission underestimates the corona Lyα intensity (< 10%) compared to the synchronic map, except for a slight overestimate (< 4%) in the partial CME core. The Carrington map yields lower uncertainties than the uniform disk. (2) The geometric scattering process has a minor impact on the Lyα intensity, with a maximum relative uncertainty of < 5%. The Lyα intensity is underestimated for the most part but overestimated in the CME core. (3) Compared to the assumption Tn = Tp, using Tn = Te leads to more complex relative uncertainties in CME Lyα intensity. The CME core and void are both overestimated, with the maximum uncertainty in the core exceeding 50% and the void remaining below 35%. In the CME front, both over- and under-estimates exist with relative uncertainties of < 35%. The electron temperature assumption has a smaller impact on the shock, with an underestimated relative uncertainty of less than 20%. |
| title | Parameter effects on the total intensity of H I Lyα line for a modelled coronal mass ejection and its driven shock |
| topic | Solar and Stellar Astrophysics |
| url | https://arxiv.org/abs/2406.11297 |