The role of ice in planet formation

As stars form, they are surrounded by a disc composed of gas, dust and ice – the protoplanetary disc, where solids grow from micrometre-sized dust to planets. Small dust grows readily by collisions. However, it is challenging to reach high enough particle sizes and dust-to-gas-ratios for continued growth to planetesimals – kilometre-sized and larger planetary building blocks. In this thesis I explore the effect of ice on the growth towards pebbles, in order to investigate if the water ice line – the radial distance from the star where water undergoes a phase change from
vapour to solid form – can be a favourable location for the initiation of growth towards planetesimals. In a series of papers, I numerically and experimentally investigate condensation and sublimation at the water ice line. I find that micrometre-sized dust particles can grow quickly to icy pebbles through condensation. This confirms that the water ice line can be a favourable location for further growth towards planetesimals and planets.