小行星(16) Psyche的异质表面
The Heterogeneous Surface of Asteroid (16) Psyche
AI总结：
本研究通过拟合ALMA数据发现小行星(16) Psyche表面在介电常数和热惯量上具有异质性，且两者无直接关联，表明其表面由金属与硅酸盐混合构成，并可能覆盖有细粒风化层，反映了碰撞演化历史。
摘要：
主带小行星(16) Psyche是最大的M型小行星，这类天体在经典理论中被认为是分化星子的金属核心，也是铁陨石的母体。de Kleer、Cambioni和Shepard（2021年，https://doi.org/10.3847/psj/ac01ec）展示了来自阿塔卡马大型毫米波阵列（ALMA）的新数据，他们据此推导出Psyche的全球最佳拟合热惯量和介电常数，这些参数是风化层颗粒大小、孔隙率和/或金属含量的代理指标，并观测到无法仅由表面反照率变化解释的热异常。受此启发，我们在此对同一ALMA数据集拟合了一个允许介电常数和热惯量在表面变化的模型。我们发现Psyche在介电常数和热惯量方面均具有异质表面，但有趣的是，我们并未观测到这两个属性在表面上的直接相关性。我们将介电常数的异质性解释为金属和硅酸盐相对丰度的变化所致。此外，我们观测到Psyche形状中一个大型凹陷的低洼区域具有明显低于周围高地的热惯量。我们提出后者可能由一层薄薄的细粒风化层、破碎基岩和/或植入的富硅酸盐物质覆盖在原本富含金属的表面之上来解释。所有这些情景都表明这是一个经历了碰撞演化的世界。
英文摘要：
Main-belt asteroid (16) Psyche is the largest M-type asteroid, a class of object classically thought to be the metal cores of differentiated planetesimals and the parent bodies of the iron meteorites. de Kleer, Cambioni, and Shepard (2021, https://doi.org/10.3847/psj/ac01ec) presented new data from the Atacama Large Millimeter Array (ALMA), from which they derived a global best-fit thermal inertia and dielectric constant for Psyche, proxies for regolith particle size, porosity, and/or metal content, and observed thermal anomalies that could not be explained by surface albedo variations only. Motivated by this, here we fit a model to the same ALMA data set that allows dielectric constant and thermal inertia to vary across the surface. We find that Psyche has a heterogeneous surface in both dielectric constant and thermal inertia but, intriguingly, we do not observe a direct correlation between these two properties over the surface. We explain the heterogeneity in dielectric constant as being due to variations in the relative abundance of metal and silicates. Furthermore, we observe that the lowlands of a large depression in Psyche's shape have distinctly lower thermal inertia than the surrounding highlands. We propose that the latter could be explained by a thin mantle of fine regolith, fractured bedrock, and/or implanted silicate-rich materials covering an otherwise metal-rich surface. All these scenarios are indicative of a collisionally evolved world.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
