Jonathan Marshall (ASIAA)
Planetesimals -- asteroids and comets -- are the building blocks of planets in protoplanetary discs and the source of dust, ice and gas in debris discs. Along with planets they comprise the left-over material after star formation that constitutes a planetary system. Planets influence the dynamics of planetesimals, sculpting the orbits of debris belts to produce asymmetries or gaps. We can constrain the architecture of planetary systems, and infer the presence of unseen planetary companions, by high spatial resolution imaging of debris discs. HD 16743 is a young, F-type star that hosts a bright debris disc. Based on far-infrared Herschel observations its disc was thought to be stirred by a planetary companion. Here we present high spatial resolution mm-wavelength ALMA observations, revealing the orientation and extent of the disc's underlying planetesimal belt. We use simple stirring models in conjunction with the stellar age and disc extent to infer the presence of potential planetary companion to the disc. Furthermore, we present VLT/SPHERE scattered light observations to determine the dust albedo. We model the disc extent, orientation, and scattering properties in conjunction with archival imaging and photometric observations to better constrain the dust grain properties for this system.