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

自从2007年发现Sedna以来，在过去的十年里，人们在柯伊伯带以外高度偏心的轨道上发现了一批遥远的太阳系天体(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所能到达的范围，也不可能单独通过与海王星的相互作用而分散到它们高度偏心的轨道上。IOCS的轨道距离太阳系边缘太远，感觉不到今天太阳系附近流过的恒星或银河系潮汐的扰动效应。太阳系现在或过去的结构中需要一些其他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化石记录。每一种提出的解释海委会形成的情景都在这一遥远人口的成员上留下了独特的印记，并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似乎是在天空中类似的位置出现的近日点，目前认为这是由于一颗在~200 Au或更高的位置上一颗看不见的第9颗行星的主动引力牧羊人。尽管有令人信服的证据表明，在海王星以外有可能存在一颗巨大的冰行星，但其他现代太阳系调查的结果似乎与这一假设相矛盾。为了帮助解开这个谜团，这项新的申请者计划计划试图研究这个遥远的小行星集合的起源和性质，以及它们揭示了外太阳系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.