Carbon-rich AGB stars are important contributors to the enrichment of the interstellar medium, and in their
spectra there are signs of carbon-bearing molecules such as C2, C3, C2H2, CN, or HCN, while the dust is mainly
dominated by amorphous carbon dust grains and silicon carbide. Also, AGB stars are prominent members of stellar
populations, and the most important contributors to the total flux emitted by galaxies containing populations of
young/intermediate ages.
Dynamic models for the atmospheres of C-rich Asymptotic Giant Branch stars are quite advanced and have been rather
successful in reproducing spectroscopic and photometric observations. Interferometry provides independent
information and thus an essential tool to study the atmospheric stratification and to further constrain the
dynamic models.
We present the first systematic comparison of a larger sample of C-rich Mira and semi-regular stars observed with
VLTI/MIDI with synthetic photometry, spectroscopy and visibilities derived from dynamic model atmospheres (DMA,
Eriksson et al. 2014). The SEDs can be reasonably well modelled, and the interferometry supports the extended and
multi-component structure of the atmospheres, but some differences remain. The possible reasons for these
differences and the stellar parameters derived from this comparison with stellar evolution models will be
discussed.
The high potential of MATISSE is underlined, as the second generation VLTI instrument allowing interferometric
imaging in the L, M, and N bands, for further progress in this field.
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