AST-9731445 Rood Dr. Rood and Dr. Bania are collaborating to determine the abundance of the one of those light elements, an isotope of helium, 3He. The study of the origin and evolution of the elements is one of the cornerstones of modern astrophysics. The Big Bang theory predicts that significant amounts of the light elements (2H, 3He, 4He 7Li) are produced in the first few thousand seconds of the Universe. The relative abundances of these elements depends upon details of the initial conditions in the theory. In addition, over time, nuclear fusion reactions in stars will change the relative amounts of these elements. Observations of how these elements vary with space and time provide a crucial probe to the evolution of stars and galaxies since the first few thousand seconds. The PI and Co-PI have shown that it is feasible to detect and measure these weak 3He+ emission lines, and from those measurements to derive accurate 3He abundances. The PI's are making a systematic study of 3He through the Milky Way. This project extends that work by observing a larger sample of planetary nebulae (where reprocessing of stellar material is occurring), improving the accuracy of the current abundances, observing new H II regions (where there has been new star formation), obtaining improved spectra for selected H II regions, refining the models that predict how much 3He can be present, and searching for 3He+ emission from extragalactic sources. The 3He+ emission line at 3.5 cm is observed at a wavelength of 3.5 cm. The project uses the NRAO 140 ft, the NRAO VLA, the MP1fR 100 m, Arecibo and (when operational) the 3.5 cm receiver at Green Bank. ***
