2020-10-16 Abstract
Title: Constraining the architecture of planetary systems from multi-wavelength, spatially resolved imaging
Speaker: Dr. Jonathan Marshall (ASIAA)
Date: October 16 at 14:30
Location: R521, General Building II
Abstract:
Debris discs – belts of dusty and icy planetesimals (asteroids and comets) – around main sequence stars are the long-lived remnants of dust- and gas-rich protoplanetary discs – the birthplace of planetary systems. A rich variety of structures have been identified in protoplanetary discs, but little correlation has been found between the radial location of annular structures and ice lines around the host stars. This led to the speculation that these structures could be due to the presence of protoplanets. The enhanced surface density of solid material in protoplanetary discs around ice lines, particularly water ice but also CO, has been proposed as a mechanism to quicken the planet(esimal) formation process. If this interpretation were correct, we might expect that debris discs would lie close to the predicted locations of ice lines in their host stars' long since dissipated protoplanetary discs. A trend between disc radius and stellar luminosity was first identified in millimetre-wavelength interferometric imaging of debris discs, following the expected slope for planetesimal formation at the CO ice line, albeit with some scatter. The same trend is recoverable from far-infrared imaging observations of debris discs. From the variety of structures (e.g. gaps, warps, offsets) and presence of dynamically excited components (i.e. exocomets) seen in debris discs, we infer that disc–planet interactions are essential to the observed architectures of planetary systems. In this talk I will focus on presenting the results of modelling 100 spatially resolved debris discs at far-infrared wavelengths with Herschel. The disc architectures were systematically determined using a single annulus architecture and MCMC fitting technique. Inferred trends for the properties of the constituent dust grains for these systems were obtained through analysis of the spatially resolved extents in concert with radiative transfer models. I will link the results of this analysis to ongoing work combining these data with scattered light observations (both polarimetric and total intensity) to refine our understanding of the dust optical properties and composition. Finally, I will discuss future prospects for interpreting the architectures of planetary systems and tracing disc-planet interactions through the observable properties of debris discs across a range of wavelengths.