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Paper: Observations and Modeling of the Nonuniform Dust Outflow Around the Red Supergiant NML Cygni
Volume: 135, A Half Century of Stellar Pulsation Interpretations: a Tribute to Arthur N. Cox
Page: 329
Authors: Monnier, J. D.; Bester, M.; Danchi, W. C.; Johnson, M. A.; Lipman, E. A.; Townes, C. H.; Tuthill, P. G.; Geballe, T. R.
Abstract: Measurements by the University of California Berkeley Infrared Spatial Interferometer at 11.15 microns have yielded strong evidence for multiple dust shells andor significant asymmetric dust emission around NML Cyg. A comprehensive set of both recent and past measurements is analyzed and fitted to a model of the dust distribution around NML Cyg. No spherically symmetric single dust shell model is found consistent with both near-and mid-infrared observations. However, a circularly symmetric maximum entropy rconstruction of the 11 micron brightness distribution suggests a double shell model for the dust distribution. Such a model is found consistent not only with the 11 micron visibility data, but also with near-infrared speckle measurements, the broadband spectrum, and the 9.7 micron silicate feature. The outer shell at a radius of 350 mas is revealed only by long-baseline interferometry at 11 microns, being too cold (~300K) to contribute in the near-infrared and having no unambiguous spectral signature in the mid- infrared.
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