Dayside nitrogen and carbon escape on Titan: the role of exothermic chemistry | |
Gu, H.4; Cui, J.2,5,6; Lavvas, P. P.7; Niu, D-D4; Wu, X-S2,6; Guo JH(郭建恒)1; He, F.3; Wei, Y.3 | |
刊名 | ASTRONOMY & ASTROPHYSICS |
2019-12-20 | |
卷号 | 633页码:20 |
关键词 | planets and satellites atmospheres planets and satellites individual Titan |
ISSN号 | 0004-6361 |
DOI | 10.1051/0004-6361/201936826 |
产权排序 | 第6完成单位 |
文献子类 | Article |
英文摘要 | Context. Atmospheric escape has an appreciable impact on the long-term climate evolution on terrestrial planets. Exothermic chemistry serves as an important mechanism driving atmospheric escape and the role of such a mechanism is of great interest for Titan due to its extremely complicated atmospheric and ionospheric composition. Aims. This study is devoted to a detailed investigation of neutral N and C escape on the dayside of Titan, which is driven by exothermic neutral-neutral, ion-neutral, and dissociative recombination (DR) reactions. It was carried out based on the extensive measurements of Titan's upper atmospheric structure by a number of instruments on board Cassini, along with an improved understanding of the chemical network involved. Methods. A total number of 14 C- and N-containing species are investigated based on 146 exothermic chemical reactions that release hot neutrals with nascent energies above their respective local escape energies. For each species and each chemical channel, the hot neutral production rate profile is calculated, which provides an estimate of the corresponding escape rate when combined with the appropriate escape probability profile obtained from a test particle Monte Carlo model. Results. Our calculations suggest a total N escape rate of 9.0 x 10(23) s(-1) and a total C escape rate of 4.2 x 10(23) s(-1), driven by exothermic chemistry and appropriate for the dayside of Titan. The former is primarily contributed by neutral-neutral reactions, whereas the latter is dominated by ion-neutral reactions; however, contributions from neutral-neutral and DR reactions to the latter cannot be ignored either. Our calculations further reveal that the bulk of N escape is driven by hot N(S-4) production from the collisional quenching of N(D-2) by ambient N-2, while C escape is mainly driven by hot CH3 and CH4 production via a number of important ion-neutral and neutral-neutral reactions. Conclusions. Considered in the context of prior investigations of other known escape mechanisms, we suggest that exothermic chemistry is likely to contribute appreciably to non-thermal C escape on the dayside of Titan, although it plays an insignificant role in N escape. |
学科主题 | 天文学 ; 太阳与太阳系 ; 行星物理学 |
URL标识 | 查看原文 |
出版地 | AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE |
资助项目 | Strategic Priority Research Program of the Chinese Academy of Sciences[XDA17010201] ; National Science Foundation of China (NSFC)[41525015] ; National Science Foundation of China (NSFC)[41774186] ; National Science Foundation of China (NSFC)[41525016] |
WOS关键词 | EVALUATED KINETIC-DATA ; ETHYNYL RADICAL C2H ; TEMPERATURE RATE COEFFICIENTS ; ABSOLUTE CROSS-SECTIONS ; ION MOLECULE CHEMISTRY ; ATOM BRANCHING RATIOS ; DISSOCIATIVE RECOMBINATION ; RATE CONSTANTS ; UPPER-ATMOSPHERE ; GAS-PHASE |
WOS研究方向 | Astronomy & Astrophysics |
语种 | 英语 |
出版者 | EDP SCIENCES S A |
WOS记录号 | WOS:000503792300001 |
资助机构 | Strategic Priority Research Program of the Chinese Academy of Sciences[XDA17010201] ; National Science Foundation of China (NSFC)[41525015, 41774186, 41525016] |
内容类型 | 期刊论文 |
源URL | [http://ir.ynao.ac.cn/handle/114a53/22105] |
专题 | 云南天文台_恒星物理研究组 |
通讯作者 | Cui, J. |
作者单位 | 1.Yunnan Astronomical Observatory, Chinese Academy of Sciences, Kunming, Yunnan, PR China 2.National Astronomical Observatories, Chinese Academy of Sciences, Beijing, PR China 3.Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, PR China 4.Space Science Institute, Macau University of Science and Technology, Macau, PR China 5.School of Atmospheric Sciences, Sun Yat-Sen University, Zhuhai, Guangdong, PR China 6.Chinese Academy of Sciences Center for Excellence in Comparative Planetology, Hefei, Anhui, PR China 7.Université de Reims Champagne Ardenne, CNRS, GSMA UMR 7331, 51097 Reims, France |
推荐引用方式 GB/T 7714 | Gu, H.,Cui, J.,Lavvas, P. P.,et al. Dayside nitrogen and carbon escape on Titan: the role of exothermic chemistry[J]. ASTRONOMY & ASTROPHYSICS,2019,633:20. |
APA | Gu, H..,Cui, J..,Lavvas, P. P..,Niu, D-D.,Wu, X-S.,...&Wei, Y..(2019).Dayside nitrogen and carbon escape on Titan: the role of exothermic chemistry.ASTRONOMY & ASTROPHYSICS,633,20. |
MLA | Gu, H.,et al."Dayside nitrogen and carbon escape on Titan: the role of exothermic chemistry".ASTRONOMY & ASTROPHYSICS 633(2019):20. |
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