Western Kentucky University
Cold Molecular Gas in the Diffuse Interstellar Medium
Institution
Western Kentucky University
Faculty Advisor/ Mentor
Steve Gibson
Abstract
Stars form during the collapse of cold, dense interstellar clouds. To learn more about the conditions that precede star formation, we wanted to know how such dense clouds form in turn from the ambient interstellar medium. A key step in this process is molecule formation from cold atomic gas, because molecular clouds are more opaque to starlight, so they can become even colder and denser until they collapse under their own weight and form new stars. Using radio telescopes, we observed this phase transition using atomic hydrogen (HI) 21cm-line absorption and carbon monoxide (CO) 2.6mm-line emission. Our results showed that cold HI and CO are sometimes found together in the same area but are more often separate. The level of correspondence varied significantly in different parts of the Galaxy. We showed how trends in the data relate to environmental influences on the evolution of interstellar clouds and the future of star formation in the Milky Way.
Cold Molecular Gas in the Diffuse Interstellar Medium
Stars form during the collapse of cold, dense interstellar clouds. To learn more about the conditions that precede star formation, we wanted to know how such dense clouds form in turn from the ambient interstellar medium. A key step in this process is molecule formation from cold atomic gas, because molecular clouds are more opaque to starlight, so they can become even colder and denser until they collapse under their own weight and form new stars. Using radio telescopes, we observed this phase transition using atomic hydrogen (HI) 21cm-line absorption and carbon monoxide (CO) 2.6mm-line emission. Our results showed that cold HI and CO are sometimes found together in the same area but are more often separate. The level of correspondence varied significantly in different parts of the Galaxy. We showed how trends in the data relate to environmental influences on the evolution of interstellar clouds and the future of star formation in the Milky Way.