RUI: Observational Studies of Supernova Remnants and the Interstellar Medium

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AST 0307613Winkler Supernovae are the cataclysmic events in which massive stars end their lives. A typicalsupernova explosion releases in a few seconds an energy of about 1044 Joules, comparable to what the Sun will expend throughout the entire course of its lifetime. Such a prodigious release ofenergy has profound effects on the dynamics of galaxies in which supernovae occur; for example, the shock waves from supernovae can trigger episodes of star formation when they encounter denseinterstellar clouds. Supernovae are responsible for the production and distribution of most of the heavy elements in the universe. Virtually all the elements from helium to iron on the periodic table were forged by nucleosynthesis in the cores of massive stars and distributed around the cosmos through supernova explosions. The overall goal of this project, led by Dr. Frank Winkler at Middlebury College, is to achieve a better understanding of how supernovae explode, how their prodigious energy release affects their host galaxies, and how they contribute to the chemical evolution of the Universe. For young supernova remnants (SNRs) where uncontaminated ejecta from the supernova can be identified, spectroscopy will lead to chemical abundances of these fragments of the stellar core and provide information about the nucleosynthesis processes that produced them. Current models suggest that supernova explosions must be asymmetric; proposed velocity measurements of surviving knots of ejecta and of recoiling neutron stars can test these theories. In the far more numerous remnants that are older and larger, expanding shocks can probe the density, structure, and abundances of the interstellar medium. Images of dozens of remnants as seen in emission lines of hydrogen, oxygen, and sulfur will be compiled into an Emission-Line Atlas of SNRs. Widely available on-line as well as in printed form, the optical images will dramatize the dynamic processes that shape the cosmos for the general public and will serve as a resource for astronomers to combine with images at X-ray, radio, and other wavelengths. The Magellanic Cloud Emission-Line Survey (MCELS) has imaged both the Large and Small Magellanic Clouds, nearest neighbor galaxies to our own, from the 0.6-m Schmidt telescope at Cerro Tololo Inter-American Observatory (CTIO). The deep emission-line images it provides will be analyzed to study the interstellar medium on all scales-from tiny planetary nebulae, to supernova remnants, to giant supershells carved by multiple supernova blasts-unimpeded by the dust that blocks our view in the Milky Way. Statistical studies of these entire galaxies, as well as detailed probes of individual objects within them, will be pursued in collaboration with astronomers at CTIO and elsewhere. The integral role that undergraduate students will play in all phases of this research is the mostimportant broader impact of this project. As early as their first or second year, an able student will be able to complete the image analysis for an individual object. More complex projects will require the development of sophisticated analytical tools and manipulation of large data sets-enough to challenge the most ambitious senior honors candidate. For those students who follow careers in astronomy or physics, as well as for those whose career paths take other directions, the experience of grappling independently with unanswered, often subtle, questions during their undergraduate years will leave them better equipped to face future challenges. Research students will themselves contribute to the broader impact by assisting in the popular program of public nights at the Middlebury College Observatory. An even broader impact for the general public will be the striking images, available over the web and published in popular literature, from the Emission-Line Atlas and the MCELS. This award is made under the auspices of the Research at Undergraduate Institutions (RUI) program at NSF.***