H2 Emission in Outer Planet Atmospheres

外行星大气中的 H2 排放

• 批准号: 0407310
• 负责人: Laurence Trafton
• 金额: $ 7.5万
• 依托单位: University of Texas at Austin
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-06-01 至 2008-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0407310&HistoricalAwards=false
• 关键词: H2; Emission; Outer; Planet; Atmospheres

AST 0407310TraftonIdentifying the main sources of thermospheric heating on the giant planets remains a major unsolved problem in planetary science today. The known sources of heating cannot explain their high temperatures. So some other process must be playing the dominant role. In the upper thermospheres and ionospheres of the giant planets, the collision rate becomes too low to maintain a Boltzmann population of energy levels vacated by spontaneous and induced emission, or visited by cascade following fluorescent or electron-impact excitation. This departure from local thermodynamic equilibrium (LTE) means that the observed spectrum will bear the signature of the physical and chemical processes operating in these upper atmospheres. Observations of outer-planet IR emission spectra, particularly the H2 quadrupole lines,are needed to constrain the processes and parameters of non-LTE emission models, in order to infer the structure and energy balance of these upper atmospheres and ionospheres. Such observations will insure that the important chemical processes taking place in these atmospheres will be included in the emission model, and will then allow the dominant source of thermospheric/ionospheric heating to be identified.Dr. Laurence Trafton will obtain these needed observations in a comparative study of outer planet thermospheres that involves surveying the near-and mid-infrared H2 quadrupole line emission over multiple vibrational levels. The results will be applied to constraining the non-LTE emission model developed by Dr. Don Shemanski at the University of Southern California (USC) and in preliminary modeling of the structure and energy balance of these upper atmospheres. A comparative, parametric study of processes in our own giant planets is needed in order to extrapolate to the environments of other bodies. Comparative planetology can provideinsights into atmospheric processes of extra-solar giant planets. Another broader impact ofthis program will be to provide baseline reference data for future studies of solar cycle andseasonal effects on these planets. Finally, by supporting the development of the USC emission model, the proposed observations will help to support the Cassini Orbiter UVIS mission, which will be taking place during the grant period, because the UVIS team will be applying the USC emission model to the analysis of their data.***

AST 0407310Trafton 确定巨行星热层加热的主要来源仍然是当今行星科学中尚未解决的主要问题。已知的热源无法解释它们的高温。因此，一定有其他进程在发挥主导作用。在巨行星的上层热层和电离层中，碰撞率变得太低，无法维持自发和感应发射所腾出的玻尔兹曼能级布居，或者在荧光或电子撞击激发后通过级联访问。这种偏离局部热力学平衡（LTE）意味着观测到的光谱将带有这些高层大气中物理和化学过程的特征。需要对外行星红外发射光谱，特别是 H2 四极线的观测来约束非 LTE 发射模型的过程和参数，以推断这些高层大气和电离层的结构和能量平衡。此类观测将确保这些大气中发生的重要化学过程将包含在排放模型中，然后将能够识别热层/电离层加热的主要来源。劳伦斯·特拉夫顿将在外行星热层的比较研究中获得这些所需的观测结果，该研究涉及在多个振动水平上测量近红外和中红外 H2 四极线发射。结果将应用于约束南加州大学 (USC) 的 Don Shemanski 博士开发的非 LTE 排放模型，以及这些高层大气的结构和能量平衡的初步建模。需要对我们自己的巨行星的过程进行比较、参数研究，以便推断其他天体的环境。比较行星学可以深入了解太阳系外巨行星的大气过程。该计划的另一个更广泛的影响将是为未来研究太阳周期和季节性对这些行星的影响提供基线参考数据。 最后，通过支持 USC 发射模型的开发，拟议的观测将有助于支持卡西尼轨道飞行器 UVIS 任务，该任务将在拨款期间进行，因为 UVIS 团队将应用 USC 发射模型来分析他们的数据。***