Multi-spectral Observations of Lunar Occultations: I. Resolving The Dust Shell Around AFGL 5440 - AstrophysicsReport as inadecuate




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Abstract: We present observations and modeling of a lunar occultation of thedust-enshrouded carbon star AFGL 5440. The observations were made over acontinuous range of wavelengths from 1 - 4um with a high-speedspectrophotometer designed expressly for this purpose. We find that theoccultation fringes cannot be fit by any single-size model. We use the DUSTYradiative transfer code to model a circumstellar shell and fit both theobserved occultation light curves and the spectral energy distributiondescribed in the literature. We find a strong constraint on the inner radius ofthe dust shell, Tmax = 950 K +- 50K, and optical depth at 5um of 0.5 +- 0.1.The observations are best fit by models with a density gradient of r^-2 or thegradient derived by Ivezic and Elitzur for a radiatively driven hydrodynamicoutflow. Our models cannot fit the observed IRAS 60um flux without assuming asubstantial abundance of graphite or by assuming a substantially highermass-loss rate in the past.



Author: Paul M. Harvey, Andrew Oldag

Source: https://arxiv.org/







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