Lecture 17 March: “Brown Dwarfs and Planetary Mass Objects…” by Mary Barsony, PhD

Full Lecture Title: “Brown Dwarfs, Planetary Mass Objects, and their Disks in the Nearest Star Forming Regions”

Objects with masses (<0.08 solar masses) too small to sustain hydrogen fusion were theorized to exist five decades ago, and discovered 30 years later, due to their extreme faintness. Even less massive (<13 Jupiter or <0.01 solar masses) are the planetary mass objects (PMOs), so-called because they are not orbiting a star. We have discovered large populations of such free-floating PMOs and brown dwarfs in the nearest star-forming regions to Earth, when they are at their brightest and most amenable to detection. Do such objects outnumber the stars in the Galaxy? Do they have their own planetary or moon systems? Could these sustain surface or subsurface liquid water for eons via tidal heating and thus provide environments conducive for the development of microbial life? Dr. Mary Barsony is a Principal Investigator at the Carl Sagan Center for the Study of Life in the Universe at the SETI Institute and Adjunct Professor of Physics and Astronomy at San Francisco State University. She has served as a faculty member at USC, Harvey Mudd College, and U.C. Riverside. She earned her Ph.D. in physics from Caltech, and her S.B. in physics from MIT. Through submillimeter observations in the early '90's, Dr. Barsony discovered the first true protostar--an object surrounded by infalling gas in the process of accumulating the mass it will have as a full-fledged star. Protostars are the focus of intense study with state-of-the-art instruments, on the Keck telescopes in Hawaii, the future JWST(James Webb Space Telecope)--scheduled for a 2018 launch, and ALMA (the Atacama Large Millimeter/Submillimeter Array)--consisting of a total of 66 radio telescopes operating as one at 16000 ft. elevation in the driest desert on Earth in Chile. Currently, Dr. Barsony is investigating the formation mechanisms and properties of free-floating planetary mass objects in the nearest star-forming regions to Earth, with state-of-the-art, near-infrared, multi-object spectrographs on the Keck and Subaru telescopes atop Mauna Kea on the big island of Hawaii.

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