Almost no in situ seismic data are available for Venus; therefore, we can constrain the deep structure of this planet only from the geodetic data obtained by spacecraft. Of particular interest is Venus’s core-mantle boundary, which holds clues about the origin and evolution of this celestial body. In this study, we build a series of different mantle/core models of Venus based on several mantle composition models and compare their associated Love numbers k₂ with the observed values. Due to the large uncertainty in the observed values of k₂, the state of Venus’s core cannot be reliably constrained. However, the expected precision of k₂ obtained by the EnVision mission will sufficiently reduce the acceptable model space and contribute to estimating the mantle viscosity structure. Based on current geodetic data, we find that the bottom of Venus’s mantle may not feature a phase transition from perovskite to post-perovskite if the FeO content of the mantle is less than 8.1 wt%; this region may be different from Earth’s D” layer. Furthermore, we find that the combination of observed k₂ and Q can be used to distinguish whether the lowermost part of Venus’s mantle is a high-temperature basalt layer or a thin thermal boundary layer if observations of Q can be obtained.

中文翻译：

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根据大地测量数据的当前知识可能的金星深层结构和组成

几乎没有金星的原位地震数据；因此，我们只能通过航天器获得的大地测量数据来限制这颗行星的深层结构。特别令人感兴趣的是金星的核心-地幔边界，它包含有关这个天体起源和演化的线索。在这项研究中，我们基于几个地幔成分模型建立了一系列不同的金星地幔/核心模型，并将它们相关的洛夫数k ₂与观测值进行了比较。由于k ₂的观测值存在很大的不确定性，因此无法可靠地约束金星核心的状态。然而，k ₂的预期精度EnVision 任务获得的 将充分减少可接受的模型空间并有助于估计地幔粘度结构。根据目前的大地测量数据，我们发现，如果地幔中的 FeO 含量低于 8.1 wt%，金星地幔底部可能不会发生从钙钛矿到后钙钛矿的相变；这个区域可能不同于地球的 D”层。此外，我们发现，观察到的组合ķ ₂和Q可以被用来区分金星的地幔的最下部分是否是高温玄武岩层或薄的热边界层如果观测Q可以得到。