Oral Presentation

Multi-wavelength aperture polarimetry of disc-host stars

Author(s): Jonathan Marshall (ASIAA) Daniel Cotton (UNSW)

Presenter: Jonathan Marshall (ASIAA)

Debris discs are the tenuous, icy and rocky remnants of planet formation processes around main sequence stars. These structures are commonly identified through the detection of continuum emission at infrared wavelengths. Measurement of these discs in scattered light are elusive, with only a handful of discs detected. The scattering properties, composition and grain shape are uniquely constrained by such observations, making them critical to modeling efforts. We have observed a sample of nearby disc-host stars with the High Precision Polarimetric Instrument, an aperture stellar polarimeter with ppm sensitivity, on the Anglo-Australian Telescope. We identify significant polarization from these targets, inferred to be the result of scattering by the circumstellar dust. We further measure the degree of polarization as a function of wavelength, revealing colour trends as a function of spectral type that we infer to be the result of different dust grain sizes around these stars.