Heavy-Metal Jupiters by Major Mergers

重金属木星的主要合并

• 批准号: 2205500
• 负责人: Eugene Chiang
• 金额: $ 42.72万
• 依托单位: University of California-Berkeley
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-09-01 至 2025-08-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2205500&HistoricalAwards=false
• 关键词: Heavy; Metal; Jupiters; Major; Mergers

A team from the University of California-Berkeley seek to understand the origin of metal-rich Jupiters, asking specifically whether they can arise from collisions between smaller protoplanets. Some Jupiter-mass extrasolar planets contain as much as 100 Earth masses of 'metals', i.e. elements other than hydrogen and helium. Such 'heavy-metal' Jupiters are not expected from the conventional theory of gas giant formation, which predicts that a gas-dominated planet originates from hydrogen and helium accreting onto a solid core having only 10 Earth masses of rock and ice. This proposal asks whether metal-rich giants can arise from collisions between massive rocky cores. During the planet formation era, pairs of cores can successively collide and merge, with each merger doubling the metal content of the merger product. Such a 'giant impacts' phase of collisional growth has long been put forward to hold for rocky planets like the Earth; this project seeks to extend this model to gas giants like Jupiter. The project will simulate the merger history of forming planet cores as well as their growth through disk gas to reproduce the observed metal contents of gas giants. The work will provide context for how our Solar System’s Jupiter may have been shaped by collisions. The work will train a graduate student to join the scientific workforce, and train undergraduate research assistants with ambitions to teach the physical sciences. The investigators will partner with local K-12 programs and high school physics teachers to educate students and teachers in modeling and research. Concurrent mergers and gas accretion from the disk will be modeled with the open-source N-body code REBOUND, outfitted with routines for gas accretion and disk torques. A 'sub-grid' code that models protoplanet interiors will provide radii for use in REBOUND’s collision algorithm. Different prescriptions for planetary gas accretion, impact-generated atmospheric mass loss, and collisional mergers — perfect vs. hit-and-run, to be modeled with fast machine-learning algorithms — will be explored. The goal is to survey the range of possible outcomes in merger + gas accretion simulations, and to reproduce the mean trend and remarkably large scatter in the empirical mass-metallicity relation for giant planets. The work will also connect to varying extents with other exo-giant observables, including semi-major axes, eccentricities, multiplicities, luminosities, and spins.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.

来自加州大学伯克利分校的一个研究小组试图了解富含金属的彗星的起源，特别询问它们是否可以从较小的原行星之间的碰撞中产生。一些太阳系外的行星含有100个地球质量的“金属”，即氢和氦以外的元素。传统的气体巨星形成理论预测，一颗以气体为主的行星起源于氢和氦在一个只有10个地球质量的岩石和冰的固体核心上的吸积。这一提议提出的问题是，富含金属的巨星是否可以从巨大的岩石核心之间的碰撞中产生。在行星形成时期，成对的核心可以连续碰撞和合并，每次合并都会使合并产物的金属含量增加一倍。这种碰撞增长的“巨大撞击”阶段长期以来一直被提出来支持像地球这样的岩石行星;这个项目试图将这个模型扩展到像木星这样的气体巨星。该项目将模拟形成行星核心的合并历史，以及它们通过盘气体的增长，以再现观测到的气体巨星的金属含量。这项工作将为我们太阳系的木星如何被碰撞塑造提供背景。这项工作将培养一名研究生加入科学劳动力队伍，并培养有抱负教授物理科学的本科生研究助理。研究人员将与当地的K-12项目和高中物理教师合作，教育学生和教师进行建模和研究。同时合并和气体吸积从磁盘将模拟与开源N体代码反弹，配备了例行的气体吸积和磁盘扭矩。一个模拟原行星内部的“子网格”代码将为REBOUND的碰撞算法提供半径。行星气体吸积，撞击产生的大气质量损失和碰撞合并的不同处方-完美与打了就跑，用快速机器学习算法建模-将被探索。目标是调查合并+气体吸积模拟中可能结果的范围，并再现巨行星经验质量-金属丰度关系中的平均趋势和非常大的分散。这项工作还将在不同程度上与其他系外巨星观测数据联系起来，包括半长轴、偏心率、多重性、光度和自旋。该奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。