the 1960's HVCs were not present in astronomers' model of the Galaxy.
Today we know that understanding where the clouds of neutral hydrogen come from is crucial to our understanding of the evolution
of galaxies. There are a number of theories* as to how and
why HVCs occur, along with a plethora of new data from various sources
to help us determine their composition. By understanding what HVCs are
made of we can begin to figure out where they may have originated
and determine which theories about HVCs are correct.
I analyzed the spectra of twelve
sources to determine the composition of the clouds lying between them
and the location of our detectors (Earth). These sources can be any
astronomical object that emits photons at a predictable rate
(i.e. galaxies). Many sightlines to such objects intersect HVCs. They generally have a relatively continuous spectrum
so the absorption by interstellar ions can be detected. Using these
absorption lines I was then able to find the overall metallicity of the