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Solar System

The Outer Solar System at the Dawn of the Legacy Survey of Space and Time



The small bodies of the Outer Solar System are the material leftover from the construction of the planets and serve as a fossil record of the Solar System’s history. These planetesimals can be broadly divided in the Centaurs, the Kuiper belt, and the Inner Oort cloud. The Kuiper belt consists of orbits beyond Neptune residing between approximately 30-250 au. Centaurs are cometary precursors that have recently diffused out of the Kuiper belt. These bodies are a transitory population on relatively short-lived chaotic orbits between Neptune and Jupiter that cross one or more of the giant-planets. The Inner Oort cloud on the other hand consists of dynamically excited and detached orbits from Neptune, with semimajor axes greater than ~ 250 au, likely scattered on to their orbits by a giant planet beyond Neptune or by a passing star.

By studying the ensemble properties (shapes, sizes, compositions, orbits, and other physical characteristics) of these planetesimals, we can probe the giant planets’ early dynamical history, explore the compositional structure of the Solar System’s primordial planetesimal disk, and study the evolution of the Solar System over time. The majority of these objects are too faint for spectroscopy with ground-based telescopes, but by measuring broad-band colours in different optical and near-infrared filters, we obtain a proxy for a planetesimal’s surface composition. By measuring the brightness of a planetesimal over time, we can estimate shape and measure rotation rates. With deep optical imaging, we can look for faint features associated with comet-like activity and explore how often these objects experience outgassing of water ice and other volatile species.

Beginning in approximately mid-2024, the Vera C. Rubin Observatory will carry out the widest and deepest optical survey to date, the Legacy Survey of Space and Time (LSST). LSST will completely change how we view the Solar System.  LSST will capture the entire available sky every few nights, providing an unprecedented dataset to explore the Solar System’s inventory.LSST is expected to discover millions of asteroids and tens of thousands of distant Solar System planetesimals, an order of magnitude more Solar System small bodies than are known today.  Many of these objects will receive hundreds of observations in multiple filters.



The project will focus on developing analysis tools and utilities for LSST Solar System science and applying these techniques to present-day LSST-precursor datasets to better understand the properties of the Kuiper belt and Centaur region. There is some flexability depending on the exact interests of the student. This could include multi-filter rotational light curve fitting to measure how the object’s brightness changes as a function of wavelength as the Kuiper belt object or Centaur rotates,  measuring the color of Centaurs in different filters to further explore the compositional map of the Outer Solar System, or examining the frequnecy of cometary-like activity in the Centaur region. Queen’s University Belfast is a member of both the ATLAS and Pan-STARRS wide-field surveys, and our group are members of the LOOK (LCO [Las Cumbres Observatory] Outbursting Objects Key) Project. We expect this project could involve analysing data from LOOK, the ATLAS survey, Pan-STARRS survey, precusor LSST-like datasets like public ZTF  (Zwicky Transient Facility) data, and LSST commissioning data. There are likely to be opportunities with this project for observations at UK-supported telescopes and observatories around the world.

If you have any questions, please contact Dr. Meg Schwamb


Lead supervisor (QUB): Dr. Meg Schwamb (