Systematic determination of dust properties for a sample of 133 spatially resolved debris discs

TL;DR

This study analyzes 133 debris discs using radiative transfer models to determine dust properties and disc architectures, revealing new trends in grain size distribution and disc mass that inform our understanding of debris disc evolution.

Contribution

It provides the first characterization of the size distribution exponent at far-infrared to millimetre wavelengths for a large sample of debris discs and identifies a new trend between size distribution and disc radius.

Findings

Distribution of size exponent q is 3.49^{+0.38}_{-0.33}.

A trend between q and R_disc suggests velocity-dependent fragmentation or grain growth.

Disc masses are consistent with those of protoplanetary discs.

Abstract

Determination of the composition and size distribution of dust grains in debris discs is strongly dependent on constraining the underlying spatial distribution of that dust through multi-wavelength, spatially resolved imaging spanning near-infrared to millimetre wavelengths. To date, spatially resolved imaging exists for well over a hundred debris disc systems. Simple analytical radiative transfer models of debris dust emission can reveal trends in disc properties as a function of their host stars' luminosities. Here we present such an analysis for 133 debris discs, calculating the dust grain minimum sizes ($s_{\rm min}$), dust masses ($M_{\rm dust}$), and exponents of the size distribution ($q$) in conjunction with their architectures determined at far-infrared or millimetre wavelengths. The distribution of $q$ at far-infrared to millimetre wavelengths is characterised for the first time, finding a value of $3.49^{+0.38}_{-0.33}$. We further newly identify a trend between $q$ and $R_{\rm disc}$, which may be indicative of velocity dependent fragmentation, or grain growth at large radii. We find the disc masses inferred from this analysis are consistent with those of protoplanetary discs. Finally, we identify samples of debris discs suitable for further characterisation at millimetre and centimetre wavelengths, expanding the number of spatially resolved systems upon which future studies of these statistics can be based.