  Most studies on melting under confinement focus only on the solid and liquid
melt phases. Despite of its ubiquity, contributions from the capillary
interface (liquid / vapor interface) are often neglected. In this study the
melting behavior of small cylindrical aggregates in vapor attached to planar
surfaces is analyzed. For the assumed boundary conditions (cylindrical solid
with a non wetting top plane and a wettable side wall) solid and the liquid
phases can coexist within a certain temperature range. Due to capillary
instability, the liquid phase can form either an axisymmetric rouloid
morphology or, above a certain threshold liquid volume fraction, a bulge
coexisting with a rouloid-like section. The corresponding melting points are
different. The analysis explicitly describes the behavior of a real system of
small aggregates of long chain alkanes on planar substrates. It also gives
qualitative insights into the melting behavior of small aggregates with
anisotropic wetting behaviors in general. It reveals in particular how melting
points and melting pathways depend on the energetic respectively morphological
pathways leading to complete melting.
