UCF AVS Astrochemistry Webinar: Dr. Stefanie Milam скачать в хорошем качестве

UCF AVS Astrochemistry Webinar: Dr. Stefanie Milam

Probing the formation of complex organics in cometary ices: A New Laboratory Approach With new detector/spectrometer technology, observing facilities, and the ESA/Rosetta mission, we are discovering the molecular complexity that exists within cometary comae and starting to gain further understanding into how these species may be preserved from the interstellar medium (ISM), formed within the nucleus, and/or during radiation processing and sublimation. The Rosetta mission to comet 67P/Churyumov–Gerasimenko demonstrated the large molecular inventory of species that are not quite detectable from ground-based facilities and/or we have yet had an opportunity to search for them with the sensitivity necessary for detection. However, other ground-based observatories, such as ALMA, have shown that some simple species are formed within the coma and likely derive from more complex parent species (not identified to date). It has been shown that ices provide a catalytic surface for complex organic molecule formation on interstellar dust grains and/or in cometary ices. When the ice is warmed (e.g. during star formation or when a comet approaches a star) many species desorb into the gas phase, but the relationship between ice and gas compositions is hardly understood. A new experimental technique for identifying species that desorb from interstellar/cometary ice analogs via millimeter/submillimeter spectroscopy has been developed to understand the connection between ice and gas compositions detected in comets and the ISM. This spectroscopic approach provides several benefits for laboratory ice studies including laboratory spectra that are directly comparable to observational spectra, structure-specific identification of complex mixtures containing species of the same mass, and measurement of rotational temperature and column density of the desorbed species. The benefits of combining IR spectroscopy, mass spectrometry, and mm/submm spectroscopy to identify photoproducts will be discussed; and new results for UV photolyzed methanol ices at low temperature (~10 K) will be presented. Speaker Biography: Dr. Milam works in the Astrochemistry Laboratory at the NASA Goddard Space Flight Center (Greenbelt, Maryland USA). She is an expert in rotational spectroscopy, observations, and laboratory modeling of astrochemistry and molecular astrophysics of the interstellar medium, evolved stars, star formation regions, and comets with an emphasis on isotopic fractionation and astrobiology of primitive materials. She began pursuing a career as an Astrobiologist/Astrochemist by obtaining a B.S. in Chemistry at Kansas Wesleyan University (Salina, KS) in 2002. Her graduate studies pushed her realm of expertise to millimeter/submillimeter astronomy while working for Prof. Lucy Ziurys at the University of Arizona (Tucson, AZ). Her thesis included studies of comets, evolved stars, molecular clouds, and planetary nebulae. Throughout this work she became involved in NASA’s Deep Impact Ground Based observing team as well as numerous exchange programs with the NASA Astrobiology Institute. In an attempt to gain a further understanding of astronomical observations she conducted throughout graduate school, she opted to work in the Ames Astrochemistry laboratory with Scott Sandford studying photolysis ice chemistry. Dr. Milam maintains a renowned observational program with radio telescopes around the world, and with space-based observatories, to routinely observe comets as part of an international collaboration. Additionally, she conducts high resolution spectroscopic studies of evolved stars, star forming regions, and the Galactic interstellar medium, specializing in isotopes. She also has a laboratory dedicated to simulate interstellar/cometary/planetary ices and detect trace species employing the same techniques used for remote observations to help constrain the chemical complexity of the ices, the amount of processing that occurs, and interpret past and present data from missions that observe ice features. As Deputy Project Scientist for Planetary Science of the James Webb Space Telescope, she helped establish the next generation space telescope as a planetary science resource, engaged the community in future observations and preparations, and assisted the project to ensure the capabilities of the observatory were suitable for solar system observations. She has also lead the study team for solar system science for WFIRST and is a member of the Origins Space Telescope Science and Technology Definition Team. Tuesday, June 2, 2020