Numerical simulations of the thermo-chemical evolution of the cores of Ganymede and Europa and implications for magnetic field generation in terrestrial planets

木卫三和木卫二核心热化学演化的数值模拟及其对类地行星磁场产生的影响

• 批准号: 169803253
• 负责人: Professorin Dr. Doris Breuer
• 金额: --
• 依托单位: Institut für Planetenforschung
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2010
• 资助国家: 德国
• 起止时间: 2009-12-31 至 2013-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/169803253?language=en
• 关键词: Numerical; simulations; thermo; chemical; evolution

One of the most compelling discoveries of the Galileo mission was the detection of a selfsustained magnetic field at Jupiter’s moon Ganymede. In the present project, the thermochemical evolution and the magnetic field history of Ganymede will be modelled using parameterized convection, a thermodynamic description of core processes driving the dynamo, and dynamo models of cores with iron snowfall and iron-sulfide flotation. The aim is to understand how parameters such as core composition and mantle rheology would constrain core convection (thermal or compositional) and dynamo action in the core and to come up with an explanation for the magnetic field of Ganymede. At the same time we need to provide an explanation why a field is lacking on Europa. Recent experimental data on the Fe-FeS system suggest that the dynamo in Ganymede may be compositionally driven but that it may function substantially different than the geodynamo. In the latter, an inner core grows from below driving convection in the core and the dynamo. In Ganymede (and in Europa) the core may freeze via precipitation and the fall of Fe snow and/or through the floating of FeS flakes. This may occur in cores sufficiently close to the eutectic composition in sufficiently small planets and satellites. We will discuss the application of the model to other planets such as Mars.

伽利略使命最引人注目的发现之一是在木星的卫星木卫三上探测到了一个自我维持的磁场。在本项目中，木卫三的热化学演化和磁场的历史将使用参数化对流，驱动发电机的核心过程的热力学描述，和发电机模型的核心与铁降雪和硫化铁浮选建模。其目的是了解如何参数，如核心组成和地幔流变学将约束核心对流（热或成分）和发电机行动的核心，并拿出一个解释木卫三的磁场。与此同时，我们需要提供一个解释，为什么欧罗巴上缺少一个字段。最近关于Fe-FeS系统的实验数据表明，木卫三的发电机可能是由成分驱动的，但它的功能可能与地球发电机有很大的不同。在后者中，内核从下面生长，驱动内核和发电机中的对流。在木卫三（和木卫二），地核可能会因铁雪的沉降和/或硫化亚铁的漂浮而冻结。这可能发生在足够小的行星和卫星的核心足够接近共晶成分。我们将讨论该模型在火星等其他行星上的应用。