OBSERVATIONS, MODELING AND THEORY OF DEBRIS DISCS
B. Matthews (National Research Council of Canada, Victoria, Canada),
G. Bryden (Jet Propulsion Laboratory, United States),
C. Eiroa (Universidad Autonoma de Madrid, Spain),
A. Krivov (Friedrich Schiller University, Astrophysical Institute, Germany),
M. Wyatt (University of Cambridge, Institute of Astronomy, Cambridge, United Kingdom)
Main sequence stars, like the Sun, are often found to be orbited by circumstellar material that can be
categorised into two groups, planets and debris. The latter is made up of asteroids, comets, as well
as the dust derived from them, which makes debris discs observable in thermal emission or scattered
light. These discs may persist over Gyrs through steady-state evolution and/or may also experience
sporadic stirring, rendering them atypically bright for brief periods of time. Most interestingly, they provide
direct evidence that the physical processes (whatever they may be) that act to build large oligarchs
from micron-sized dust grains in protoplanetary discs have been successful in a given system, at least
to the extent of building up as significant a planetesimal population as that seen in the Solar Systems
asteroid and Kuiper Belts. Such systems are prime candidates to host even larger planetary bodies
as well. The recent growth in interest in debris discs has been driven by observational work that has
provided statistics, resolved images and discoveries of new classes of objects. These datasets, from
the Spitzer Space Telescope and the Herschel Space Observatory in particular, but also from near-IR
interferometers, ALMA and the new submillimetre camera SCUBA-2 provide an unprecedented census
of the hot, warm and cold components of debris discs, in many cases resolving the emission. Since
2005, the field has gone from just over a dozen resolved discs at any wavelength to resolution of over
70 discs with Herschel alone, many at multiple wavelengths, a major observational step forward. ALMA
will be able to provide observations with resolutions comparable to optical facilities, which promises
to significantly impact our understanding of the substructure of debris discs, and potentially provide
a window into the planetary systems with which they co-exist. The interpretation of this vast and expanding
dataset has necessitated significant advances in debris disc theory. Application of this theory
has led to the realization that such observations provide a powerful diagnostic that can be used not
only to refine our understanding of debris disc physics, but also to challenge our understanding of how
planetary systems form and evolve.
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