Neptune Trojans and the DEEP L5 NT survey & Velocity-imaging of planetary discs around white dwarfs

Friday, 24 September 2021 noon — 1 p.m. MST

Edward Lin (UofM) & Christopher Manser (ICL)
Edward Lin, University of Michigan
Neptune Trojans and the DEEP L5 NT survey
The resonant populations of Trans-Neptunian Objects (TNOs) are remnants of our primordial Solar System and record critical information concerning giant planet formation and evolution, and the 1:1 mean-motion mean-motion resonance remains the strongest and simplest one. Symmetric 1:1 resonators, which librate around the Lagrange point L3, shave horseshoe orbits. However, due to the complexity of interactions in the outer solar system, they usually are not long-term stable.  On the other hand, the asymmetric 1:1 resonators librate around the Lagrange point L4 or L5 are so-called Trojans. They can be stable for the age of the Solar system. This stability means that Trojans could be primordial and record details of the early solar system. The Trojans of Neptune, although there are only about 27 known members, are projected to be the largest Trojan population of our solar system. However, they are difficult to search due to the ~30AU distance.
In this talk, I will outline our current knowledge about Neptune Trojan populations, including their size, orbital, and color distributions, and how these properties tie to their formation and evolutionary history. I will also introduce our ongoing sky survey project: the DEEP L5 NT survey, and show how this new survey testing the formation and evolution models of Neptune Trojans by measuring the symmetric/asymmetric between the L4 and L5 Neptune Trojan populations, as well as demonstrate our techniques to search slow-moving objects down to r~26.5 magnitude,  which is corresponding to ~30km diameter sized Neptune Trojan


Christopher Manser, Imperial College London

Velocity-imaging of planetary discs around white dwarfs 

The majority of exo-planet host stars will evolve into red giants and end their lives as white dwarfs - degenerate stellar remnants that will slowly cool over time. In recent decades, a mountain of evidence has shown that up to half of planetary systems survive this evolution and are predominantly observed via their destruction. Planetary material that passes too close to their white dwarf (~1 Solar radius), will usually be tidally disrupted, and form a planetary debris disc that will be accreted by the white dwarf. 

A rare subset of these planetary debris discs host double-peaked atomic emission lines that reveal detailed information about the velocity structure in the disc. Using Doppler Tomography, a method analogous to CT scans used in hospitals, we can image these discs and reveal insights into their structure and evolution. In my talk I will show how we observe these gaseous planetary discs, how I have used Doppler tomography to produce velocity images of these discs, and what they can tell us about exo-planetary systems.