Short answers, pulled from the story.
Astronomer Hayashi calculated that water ice could condense at a distance of 2.7 astronomical units from the Sun in 1981. This measurement marked the boundary where volatile compounds like ammonia and methane transitioned from gas to solid grains.
Podolak and Zucker published data in 2010 showing water ice forms between 3.0 and 3.2 AU depending on pressure models. Martin and Livio proposed a single value of 3.1 AU in 2012.
Ceres orbits at 2.77 astronomical units, placing it almost exactly at the estimated formation boundary. This dwarf planet possesses an icy mantle and possibly a subsurface ocean.
Giant planets require the abundance of ices found beyond the boundary to reach their massive sizes. Without these extra materials, planetary cores would struggle to attract thick atmospheres.
Thermal instability occurs on timescales of 1,000 to 10,000 years and may cause periodic deposition of dust. This creates narrow circumstellar rings rich in material.