Bright rimmed globules and their more evolved
cousin the cometary globule represent fascinating dynamic structures
formed by the interplay of cold molecular clouds and hot ionizing
stars. Typically the head of the globule faces a hot O-type star.
Intense radiation from the star boils away lower density gas from
the head. The evaporated rim of gas becomes ionized by the stars
ultraviolet flux forming a bright glowing rim we associate with
many of these globules including CG4. Intense stellar winds from
the ionizing star evaporate gas and dust away from the head forming
the "tail" and completing the cometary shape. The globules
are known to be the birthplace of low mass stars. Stars form within
the globules by the mechanism known as "radiation driven
implosion". This process occurs when ultraviolet flux from
a hot star compresses surviving clumps of cold molecular gas eventually
causing collapse and core formation within the dense compact clouds.
Lower and intermediate mass stars ultimately form from the compact
gas and dust within the globules.