New Applicant Scheme Consolidated Grant Application in Solar System Studies- Towards the Solar System's Edge: Exploring the Inner Oort Cloud

自2007年发现塞德娜以来，在过去的十年中，人们在柯伊伯带以外的高偏心轨道上发现了一群遥远的太阳系天体（通常被称为内奥尔特云天体[IOCs]）。这些遥远的小天体的存在挑战了我们对太阳系的理解。这些轨道远远超出了已知的巨行星的范围，并且无法单独与海王星相互作用而分散到它们的高偏心轨道中。IOC的轨道距离太阳系边缘太远，无法感受到现今太阳系附近经过的恒星或银河潮汐的扰动效应。在太阳系当前或过去的结构中，需要一些其他的机制来将这些极端的太阳系小行星安置在它们的轨道上。这些遥远的小行星的轨道是它们形成的详细记录。每一种解释IOCs形成的假设都给这个遥远的族群留下了独特的印记，对我们理解太阳系的起源和演化产生了深远的影响。大多数已知的IOC似乎都在天空中的类似位置到达近日点，目前认为这是由于一颗看不见的第九行星在~200 Au或更高的地方的引力作用。虽然有令人信服的证据表明海王星之外可能存在一颗冰巨星，但现代太阳系其他调查的结果似乎与这一假设相冲突。为了帮助解开这个谜团，这个新申请人计划的提案旨在研究这个遥远的星子集合的起源和性质，以及它们揭示了太阳系外的动力学历史和环境。

Since the discovery of Sedna in 2007, the past decade has seen the discovery of a population of distant Solar System objects (often referred to as Inner Oort cloud objects [IOCs]) on a highly eccentric orbits beyond the Kuiper belt. The very existence of these distant small bodies challenges our understanding of the Solar System. These orbits are well beyond the reach of the known giant planets and could not be scattered into their highly eccentric orbits from interactions with Neptune alone. IOCs orbit too far from the edge of the Solar System to feel the perturbing effects of passing stars or galactic tides in the present-day solar neighborhood. Some other mechanism in the Solar System current or past architecture is required to emplace these extreme Solar System minor planets on their orbits. The orbits of these distant planetoids are the fossilized record of their formation. Each of the proposed scenarios offered to explain the formation of the IOCs leaves a distinctive imprint on the members of this distant population and has profound consequences for our understanding of the Solar System's origin and evolution. The majority of the known IOCs appear to come to perihelion at similar locations on the sky, which is currently proposed to be due to the active gravitational shepherding from an unseen 9th planet at ~200 au or beyond. Although there is compelling evidence to suggest the possibility of an ice giant planet beyond Neptune, there are results from other modern-day out Solar System surveys that seem to conflict with this hypothesis. To help unravel this mystery, this New Applicant Scheme proposal seeks to study the origin and properties of this distant collection of planetesimals and what they reveal about the dynamical history and environment of the outer Solar System.