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THE CORNELL HIGH-ORDER ADAPTIVE OPTICS SURVEY FOR BROWN DWARF COMPANIONS AND RELATED INSTRUMENTATION STUDIES FOR BROWN DWARF RESEARCH
I begin this publication with a description of the procedures and results for the Cornell High-order Adaptive Optics Survey (CHAOS) for brown dwarf companions to stellar systems. This survey consisted of near-infrared coronagraphic observations of 80 stars out to 22 parsecs. The subsequent data analysis revealed that zero systems showed conclusive evidence for a brown dwarf companion. Accompanying Monte Carlo population simulations determined a brown dwarf companion upper limit of 9.7% for the 25-100 AU semi-major axis region. Such a value indicates, at an 89% confidence level, that the "brown dwarf desert" around stellar objects extends further than has been previously reported. Following my descriptions of the CHAOS survey, I continue with a discussion of HD150451C, a likely white dwarf companion to the binary system HD150451AB. This object, discovered in the course of the CHAOS survey, shows infrared colors and H-band spectra consistent with a white dwarf. Common proper motion measurements confirm its classification as a physical companion. A mass estimate of 0.6-1.3 solar masses constrains it among the population of medium to very large (i.e. approaching the Chandrasekhar mass) white dwarf stars. We discuss the implications of such a classification for the stellar system's origins and history. I conclude with a description of my work in the design, fabrication, and commissioning of WIRC, a state of the art wide-field infrared camera for the Palomar 200-inch Hale telescope. The instrument, along with the collecting power of the Palomar 200-inch Hale telescope, is currently the most powerful system in the world for wide-field infrared surveys. It presently resides at Palomar Observatory as a full-time facility instrument.
Committee Members: James Houck (chair), Peter Gierasch, Daniel Schwarz, Eanna Flanagan
brown dwarfs; adaptive optics; infrared instrumentation; white dwarfs; astronomy
dissertation or thesis