Seminar: Dust around red giant stars: Inhomogeneous circumstellar environments

There exists circumstellar dust in many forms and sizes. My current research focusses on radiative transfer simulations through 3D distributions of dust around red giant stars. However, my PhD was on debris discs around main sequence solar-like stars. Thus, I will start with an overview of circumstellar dust and cirumstellar environments (CSEs) of red giant stars. The second half will focus on my paper on similarities and differences in spectral energy distributions (SEDs) of dust in spherical and disc-like morphologies around asymptotic giant branch (AGB) stars.

Using the O-rich AGB star EP Aqr as a case study, we found that it is difficult to distinguish spectral differences of dust in different morphologies. However, high optical thickness of disc-like dust distributions results in a variety of effects. For example, the dust's spectral features are less prominent and the dust may also appear as both colder and less abundant than it actually is. We found that if a spherical CSE is assumed for an observation of an AGB-star, instead of a disc-like distribution, then the mass loss rate of that AGB-star may be over-estimated (when using SED fitting) by as much as one to two orders of magnitude.

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We shall take the speaker to lunch at 12:25. There will be fika after the seminar.