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

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.

Public engagement and outreach will be an integral component of the proposed grant activities. The proposed research activities if funded would be integrated into on-going Astrophysics Research Centre (ARC) outreach programmes at Queen's University Belfast (QUB) and used to develop new activities to expand this public engagement portfolio.

To reach the broader public, a blog, chronicling the progress of our distant Solar System searches would be set up. The results of the proposed consolidated grant work will be present at least 1 talk per year at public seminars at venues such as the Irish Astronomical Association (IAA) monthly meetings and Northern Ireland Science Festival. This year begins an expansion of ARC's Northern Ireland Science Festival efforts and this year ARC will organizing QUB Astronomy Day, a full day of family friendly astronomy-related booths, demonstrations, and hands-on activities based our consolidated grant activities. Future iterations of this event would include developing interactive activities related to the proposed distance Solar System search and its discoveries. We also plan to include visiting work experience students in our proposed work activities and contribute to school student workshops.