SUPRATHERMAL ELECTRONS IN TITAN'S SUNLIT IONOSPHERE: MODEL-OBSERVATION COMPARISONS
文献类型：期刊论文
| 作者 | Vigren, E.1; Galand, M.2; Wellbrock, A.3; Coates, A. J.3; Cui, J.4,5 ; Edberg, N. J. T.1; Lavvas, P.6; Sagnieres, L.2; Snowden, D.7; Vuitton, V.8
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| 刊名 | ASTROPHYSICAL JOURNAL
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| 出版日期 | 2016-08-01 |
| 卷号 | 826期号:2 |
| 关键词 | molecular processes planets and satellites: individual (Titan) |
| 英文摘要 | The dayside ionosphere of the Saturnian satellite Titan is generated mainly from photoionization of N-2 and CH4. We compare model-derived suprathermal electron intensities with spectra measured by the Cassini Plasma Spectrometer/Electron Spectrometer (CAPS/ELS) in Titan's sunlit ionosphere (altitudes of 970-1250 km) focusing on the T40, T41, T42, and T48 Titan flybys by the Cassini spacecraft. The model accounts only for photoelectrons and associated secondary electrons, with a main input being the impinging solar EUV spectra as measured by the Thermosphere Ionosphere Mesosphere Energy and Dynamics/Solar EUV Experiment and extrapolated to Saturn. Associated electron-impact electron production rates have been derived from ambient number densities of N-2 and CH4 (measured by the Ion Neutral Mass Spectrometer/Closed Source Neutral mode) and related energy-dependent electron-impact ionization cross sections. When integrating up to electron energies of 60 eV, covering the bulk of the photoelectrons, the model-based values exceed the observationally based values typically by factors of similar to 3 +/- 1. This finding is possibly related to current difficulties in accurately reproducing the observed electron number densities in Titan's dayside ionosphere. We compare the utilized dayside CAPS/ELS spectra with ones measured in Titan's nightside ionosphere during the T55-T59 flybys. The investigated nightside locations were associated with higher fluxes of high-energy (>100 eV) electrons than the dayside locations. As expected, for similar neutral number densities, electrons with energies <60 eV give a higher relative contribution to the total electron-impact ionization rates on the dayside (due to the contribution from photoelectrons) than on the nightside. |
| WOS标题词 | Science & Technology ; Physical Sciences |
| 类目[WOS] | Astronomy & Astrophysics |
| 研究领域[WOS] | Astronomy & Astrophysics |
| 关键词[WOS] | PHOTOIONIZATION CROSS-SECTIONS ; UPPER-ATMOSPHERE ; SPECTROMETER ; IONIZATION ; DENSITIES ; MOLECULES ; BALANCE |
| 收录类别 | SCI |
| 语种 | 英语 |
| WOS记录号 | WOS:000381977900031 |
| 源URL | [http://ir.bao.ac.cn/handle/114a11/6797]  |
| 专题 | 国家天文台_月球与深空探测研究部 |
| 作者单位 | 1.Swedish Inst Space Phys, Uppsala, Sweden 2.Imperial Coll London, Dept Phys, London SW7 2AZ, England 3.Univ Coll London, Mullard Space Sci Lab, Dorking RH5 6NT, Surrey, England 4.Chinese Acad Sci, Natl Astron Observ, Beijing 100012, Peoples R China 5.Macau Univ Sci & Technol, Lunar & Planetary Sci Lab, Macau, Peoples R China 6.Univ Reims, Reims, France 7.Cent Washington Univ, Dept Phys, Ellensburg, WA 98926 USA 8.Univ Grenoble Alpes, CNRS, IPAG, Grenoble, France |
| 推荐引用方式 GB/T 7714 | Vigren, E.,Galand, M.,Wellbrock, A.,et al. SUPRATHERMAL ELECTRONS IN TITAN'S SUNLIT IONOSPHERE: MODEL-OBSERVATION COMPARISONS[J]. ASTROPHYSICAL JOURNAL,2016,826(2). |
| APA | Vigren, E..,Galand, M..,Wellbrock, A..,Coates, A. J..,Cui, J..,...&Wahlund, J. -E..(2016).SUPRATHERMAL ELECTRONS IN TITAN'S SUNLIT IONOSPHERE: MODEL-OBSERVATION COMPARISONS.ASTROPHYSICAL JOURNAL,826(2). |
| MLA | Vigren, E.,et al."SUPRATHERMAL ELECTRONS IN TITAN'S SUNLIT IONOSPHERE: MODEL-OBSERVATION COMPARISONS".ASTROPHYSICAL JOURNAL 826.2(2016). |
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来源：国家天文台
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