Collaborative Proposal: Measuring the Composition and Structure of Rocky Extrasolar Bodies

白色矮星收集行星系统剩余的岩石物质，这些行星系统围绕着它们的宿主恒星运行，直到恒星达到生命的尽头，导致它们的行星分裂。 这些“被污染的”白色矮星可以用望远镜来研究，望远镜测量它们分解成不同波长的光。不同化学元素的特征出现在不同的波长上。 通过望远镜发现的化学元素提供了有关这些解体行星中岩石物质的大量化学成分的信息。 行星中存在的岩石类型可以从整体化学成分中重建。 科学家们提出的研究将使用光谱观测来寻找更多污染的白色矮星，并评估围绕白色矮星运行的行星体的水和岩石含量，寻找行星体中类似地球的板块构造的迹象，并研究物质从行星体到宿主恒星的路径。 该项目通过促进我们对围绕其他恒星运行的行星的组成的理解来支持NSF的使命。 研究人员将包括参加加州大学圣地亚哥分校STARS项目的学生，以及其他针对研究工作中代表性不足的群体的机构倡议。研究人员将继续对候选白色矮星进行光谱观测，以确定污染最严重的恒星。 对所有污染白色矮星的母体含水量的估计将与对被大量氢污染的白色矮星含水量的评估结合起来进行。从近100颗白色矮星的样本中，他们将估计其他行星系统中富含水的岩石体的出现率。 对于正在被岩石地壳和地幔物质污染的白色矮星子集，他们将对板块构造的化学特征进行深入搜索。对Ba和Sr的探测或深度限制将为太阳系外大规模分化的岩石体提供板块构造的可能性。 动力学模拟将研究碰撞过程剥离最外层地壳和地幔层的大规模差异化岩石体的能力，然后追踪这些喷出物及其来源的天体，以探索白色矮星是如何被来自岩石天体特定区域的物质污染的。该奖项反映了NSF的法定使命，并通过利用基金会的智力价值进行评估，更广泛的影响审查标准。

White dwarf stars collected leftover rocky material from planetary systems that orbited their host stars until the stars reached their end of life and caused their planets to break apart. These "polluted" white dwarf stars can be studied using telescopes that measure their light broken down into different wavelengths. The signatures of different chemical elements appear at different wavelengths. The chemical elements found telescopically give information about the bulk chemical composition of rocky material in those disintegrating planets. The types of rocks present in the planets can be reconstructed from the bulk chemical composition. The scientists propose studies that will use spectral observations to find more polluted white dwarf stars and assess the water and rocky content of the planetary bodies that orbited the white dwarf stars, looking for signs of earth-like plate tectonics in the planetary bodies, and studying pathways for material to travel from the planetary bodies to the host stars. This project supports the mission of the NSF by promoting our understanding of the composition of planets orbiting other stars. The investigators will include students who participate in the UC San Diego STARS program and other institutional initiatives aimed at underrepresented groups in their research efforts.The investigators will continue spectroscopic observations of candidate white dwarf stars to identify those that are most heavily polluted. Estimates of the water content for all parent bodies polluting white dwarfs will be made in combination with an assessment of the water content in white dwarfs being polluted by substantial quantities of hydrogen. From a sample of nearly 100 white dwarfs, they will estimate the occurrence rate for water-rich rocky bodies in other planetary systems. For the subset of white dwarf stars that are being polluted by rocky crust and mantle material, they will conduct a deep search for the chemical signature of plate tectonics. Detections or deep limits on Ba and Sr will inform the possibility of plate tectonics for massive differentiated rocky bodies outside the Solar System. Dynamical simulations will examine the ability of collisional processes to strip massive differentiated rocky bodies of their outermost crust and mantle layers, and then track this ejecta and the body it originated from to explore how white dwarfs get polluted by material from specific regions of a rocky body.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.