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Paper: The Black-Body Dust Excess Around the Binary Post-AGB Star HR 4049
Volume: 313, Asymmetrical Planetary Nebulae III
Page: 535
Authors: Dominik, C.; Dullemond, C.P.; Cami, J.; van Winckel, H.
Abstract: We modelled in detail the very constraining Spectral Energy Distribution (SED) of the binary post-AGB star HR 4049. The object is well studied (but poorly understood) and is seen as an example of a peculiarly evolved binary in which the refractory elements are strongly depleted ([Fe/H] = -4.8) in the photosphere. Our new long wavelength flux point, indicate the dust SED is remarkable and can be fitted with a single Black-Body spectrum (BB) from 1 μm all the way to 850 μm or, alternatively, by a sum of BB in a limited temperature range. The SED indicate the presence of a disc with a large scale height, because of the large IR reprocessing. This means the disc must be gas-rich. We developped two possible models for the disc: One involves large grains in an optically thin disc with a very limited radial extend; the second scenario argues that the SED can be modelled by a very optically thick circumbinary disc. We investigated if such a disc would indeed produce blackbody radiation by presenting results from radiative transfer calculations and we quantified the properties in the framework of (hydro)dynamic calculations. The virtues and shortcomings of both models were discussed. We refer to Dominik et al. (2003) for more detailed reading.
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