Massive Stars: The Drivers of Cosmic Evolution
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The above image is one of the most amazing pictures ever taken. Meant to be an "empty" patch of sky, the Hubble Space Telescope found galaxies as far as could see. Each galaxy has a different shape, color, history, and personality. Over the last century, astronomers have dissected the light from galaxies across cosmic time to find the culprit of galaxy evolution: massive stars.
While the space between the galaxies is dark in this image, if our telescopes could see the the gas between galaxies the entire universe would brilliantly shine. Akin to galaxies, this inter-galactic gas rapidly changes throughout cosmic time: early on it transitioned from fully neutral to completely ionized. Theorists rigorously debate the source of this cosmic reionization, but observations are beginning to hone in on a suspect: massive stars. Massive stars generate the bulk of the star light in the universe. These intense radiation fields drive gas off stellar surfaces as stellar winds which carry freshly synthesized elements, like nitrogen, into interstellar space. Their final gasps, supernova, produce most of the iron in the universe and remove gas from star-forming regions to regulate the growth of galaxies. Interactions between two orbiting massive stars generate ionizing photons that may have reionized the early universe, while the explosions of their final products produce the majority of gold and other heavy elements. Massive stars shape the entire universe. My research focuses on two observations of the effects of massive stars: galactic outflows and cosmic reionization. Click on the buttons below to discover details about both topics. |