Joachim Wiegert (Uppsala University): Dust around red giant stars: Inhomogeneous circumstellar environments

Thursday 31 Mar 2022, 14:00 → 15:00 Europe/Stockholm

80109 (Ångströmlaboratoriet)

Title: Dust around red giant stars: Inhomogeneous circumstellar environments
Speaker: Joachim Wiegert
Affiliation: Uppsala University
Time: Thursday 31 March 2022, 1400 to 1500
Location: 80109Å and also online at https://uu-se.zoom.us/j/62091586806

Abstract:

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.