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; Sagnières,L.2; Snowden,D.7; Vuitton,V.8 |
| 刊名 | The Astrophysical Journal
 |
| 出版日期 | 2016-07-27 |
| 卷号 | 826期号:2 |
| 关键词 | molecular processes planets and satellites: individual (Titan) |
| ISSN号 | 0004-637X |
| DOI | 10.3847/0004-637X/826/2/131 |
| 英文摘要 | ABSTRACT The dayside ionosphere of the Saturnian satellite Titan is generated mainly from photoionization of N2 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 N2 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 ～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. |
| 语种 | 英语 |
| WOS记录号 | IOP:0004-637X-826-2-131 |
| 出版者 | The American Astronomical Society |
| 源URL | [http://ir.bao.ac.cn/handle/114a11/36311]  |
| 专题 | 中国科学院国家天文台 |
| 作者单位 | 1.Swedish Institute of Space Physics, Uppsala, Sweden; erik.vigren@irfu.se 2.Department of Physics, Imperial College London, London SW7 2AZ, UK 3.Mullard Space Science Laboratory, University College London, Dorking, Surrey RH5 6NT, UK 4.National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012, China 5.Lunar and Planetary Science Laboratory, Macau University of Science and Technology, Macau, China 6.Université Reims Champagne-Ardenne, Reims, France 7.Department of Physics, Central Washington University, 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]. The 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.The Astrophysical Journal,826(2). |
| MLA | Vigren,E.,et al."SUPRATHERMAL ELECTRONS IN TITAN’S SUNLIT IONOSPHERE: MODEL–OBSERVATION COMPARISONS".The Astrophysical Journal 826.2(2016). |
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