Uncertainty of the physical characteristics of AGB dust shells
Authors:
M. Kocifaj
Image & caption:
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Image caption::
Uncertainty of transmission function T due to particle morphology. The spherical and irregularly shaped MgO particles are related in form of T(irreg)/T(sphere).
Description:
The properties dusty and gaseous systems are usually obtained indirectly – by analyzing their spectra, extinction curves, scattering phase function or polarization. Optical thickness of the dense dust envelopes of AGB stars is traditionally calculated by Mie scattering theory under assumption that shape of sub-micrometer sized particles may affect the measured intensity of visible radiation only negligibly. We have shown that this assumption is not correct and that the uncertainty in the detected intensity due to uncertainty of the particle shapes can reach the value of 30%. This fact indicates that the real and model sizes of dust particles may differ significantly. As a consequence, this finding can change our view on dynamical evolution and lifetime of the dust population in AGB envelopes.
Reference:
Astrophys. Space Sci. Vol. 317, no. 1-2 (2008), p. 31-38.
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