Date of Award
Doctor of Philosophy (PhD)
The interstellar medium (ISM) is a confusing, muddled place. It provides the fuel for star formation, but before that can occur, the ISM must cool and condense into molecular clouds. Even this is not enough, however. It is only the cores, contained within the clumps, contained within the clouds, which form stars. With all these nested structures, it takes an optically thin, yet still bright, tracer to uncover the processes which convert the molecular clouds into stars. Luckily, the ISM is dusty.
I use the Herschel infrared GALactic plane survey (Hi-GAL) to study molecular cloud clumps through their thermal dust emission at 500 μm. For adapting and testing the clump identification and distance techniques – developed for the Bolocam Galactic Plane Survey (BGPS) – I used six Hi-GAL maps at a representative sample of Galactic longitudes. I found many more clumps per square degree with Hi-GAL than were identified with BGPS, particularly at longitudes farther from the Galactic center, where Hi-GAL's increased sensitivity truly shines. Where I found the same clumps as BGPS, my distances and physical properties aligned well. Notably, clumps are slightly larger in Hi-GAL, where the diffuse edges are not overtaken by atmospheric noise, as was the case with BGPS.
The application of these techniques to 10°
Zetterlund, Erika Henning, "Fuel for the Star Formation Engine: Dense Molecular Cloud Clumps in the Northern Galactic Plane" (2018). Astrophysical & Planetary Sciences Graduate Theses & Dissertations. 55.