Experimental phase functions of mm-sized cosmic dust grains

TL;DR

This study measures the scattering phase functions of millimeter-sized cosmic dust grains made of different materials, revealing features consistent with observed dust rings, and highlights the need for further polarization studies to understand grain structure.

Contribution

First experimental phase functions for millimeter-sized cosmic dust grains of specific materials, covering a broad scattering angle range, with implications for astrophysical dust observations.

Findings

Phase functions show soft forward peaks and increased side/back scattering.

Results align with phase functions observed in Fomalhaut and HR 4796A dust rings.

Further polarization measurements are needed to determine grain structure.

Abstract

We present experimental phase functions of three types of millimeter-sized dust grains consisting of enstatite, quartz and volcanic material from Mount Etna, respectively. The three grains present similar sizes but different absorbing properties. The measurements are performed at 527 nm covering the scattering angle range from 3 to 170 degrees. The measured phase functions show two well defined regions i) soft forward peaks and ii) a continuous increase with the scattering angle at side- and back-scattering regions. This behavior at side- and back-scattering regions are in agreement with the observed phase functions for the Fomalhaut and HR 4796A dust rings. Further computations and measurements (including polarization) for millimeter sized-grains are needed to draw some conclusions about the fluffy or compact structure of the dust grains.