A 3D Physics-based Particle Model of the Venus Oxygen Corona: Variations with Solar Activity

Here we present an investigation of the variability of Venus' extended oxygen corona. For that, we employ a combination of a fluid model VTGCM for simulating Venus' ionosphere and thermosphere and kinetic model AMPS. We have found excellent agreement of the model results with PVO observations of the corona when the modeling is done assuming the solar maximum conditions, which corresponds to the solar conditions during the observations. We also found that the oxygen density strongly depends on the solar conditions and varies by order of magnitude over a solar cycle. That explains why the extended oxygen corona was observed only at the solar maximum. The result presented in this paper will be used in a later study of the planet's interaction with the ambient solar wind, where the corona model defines the mass loading coefficient.

本研究针对金星延展氧冕（extended oxygen corona）的变化特性展开探究。为此，本研究采用流体模型VTGCM与动理学模型AMPS的组合方案，模拟金星电离层与热层的演化过程。研究表明，当模拟采用与观测期间一致的太阳活动极大期环境条件时，模型结果与PVO对该冕层的观测数据吻合极佳。同时本研究还发现，氧粒子数密度强烈依赖于太阳活动状态，在一个太阳活动周期内可变化达一个数量级。这也解释了为何仅在太阳活动极大期才能观测到该延展氧冕。本文所呈现的研究结果，将在后续关于金星与背景太阳风相互作用的研究中得到应用，其中该冕层模型将用于确定质量加载系数。