Stars within the Milky Way and other galaxies are formed as giant clouds of gas composed primarily of hydrogen and helium collapse under their own gravity, thus heating up the gas to the point where nuclear fusion is triggered and stars are formed. The life cycles of these interstellar clouds drives the internal evolution of all galaxies. The goal of this project is to study the earliest stages of the formation of these clouds by observing the spectra from certain atomic and molecular species, which serve as tracers of these otherwise cold, dark clouds. The project will carry out these observations by using the NSF supported High Elevation Antarctic Terahertz (HEAT) telescope. Outside of space, the Antarctic plateau on which the HEAT telescope is located is one of the few places on Earth that these observations can be made. The project will use the HEAT telescope to map these giant clouds along the plane of our galaxy with unprecedented resolution and sensitivity.
Current theories of molecular cloud formation are guided and constrained by atomic (HI) and molecular (CO) observations of the cloud gas in the interstellar medium. However, HI and CO surveys are less sensitive to the early stages of the molecular cloud formation. Through measurements of CI and CII line emissivity with HEAT, the project will map the early stages of cloud formation as clouds of atomic hydrogen transition to Giant Molecular Clouds of H2. The project also plans to observe the NII line to determine the ionizing luminosity of OB stars, which is a standard metric for star formation rate. This data will be correlated with the rate of destruction of nearby GMCs as measured by the CII observations.
The HEAT telescope is a fully automated facility designed to run unattended for a year between servicing missions. The proposal points out that there are actually two fully functional HEAT telescope/receiver facilities; one that is deployed in Antarctica while the other is being refurbished in Arizona for the following year. This project will build upon previous efforts by the PI to train of a new generation of scientists and engineers by involving them not only in the science from the facility, but by providing a hands-on experience with the instrumentation as the off-duty HEAT telescope is refurbished. The project intends to communicate its results to the general public in two ways. First, the project will use the off-duty facility for public outreach demonstrations held at the University of Arizona. Second, the project intends to present the HEAT project via a program produced for PBS?s NOVA television series.
