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Hydrodynamical model atmospheres: Their impact on stellar spectroscopy and asteroseismology of late-type stars | | Hans-G. Ludwig
; Matthias Steffen
; | | Date: |
1 Sep 2016 | | Abstract: | Hydrodynamical, i.e. multi-dimensional and time-dependent, model atmospheres
of late-type stars have reached a high level of realism. They are commonly
applied in high-fidelity work on stellar abundances but also allow the study of
processes that are not modelled in standard, one-dimensional hydrostatic model
atmospheres. Here, we discuss two observational aspects that emerge from such
processes, the photometric granulation background and the spectroscopic
microturbulence. We use CO5BOLD hydrodynamical model atmospheres to
characterize the total granular brightness fluctuations and characteristic time
scale for FGK stars. Emphasis is put on the diagnostic potential of the
granulation background for constraining the fundamental atmospheric parameters.
We find a clear metallicity dependence of the granulation background. The
comparison between the model predictions and available observational
constraints at solar metallicity shows significant differences, that need
further clarification. Concerning microturbulence, we report on the derivation
of a theoretical calibration based on CO5BOLD models, which shows good
correspondence with the measurements for stars in the Hyades. We emphasize the
importance of a consistent procedure when determining the microturbulence, and
point to limitations of the commonly applied description of microturbulence in
hydrostatic model atmospheres. | | Source: | arXiv, 1609.0219 | | Services: | Forum | Review | PDF | Favorites | |
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