The carbon star adventure: modelling atmospheres of a set of C-rich AGB stars

Autor(en)

Gioia Rau, Claudia Paladini, Josef Hron, Bernard Aringer, Kjell Erikssonn, Martin Groenewegen

Abstrakt

We study the atmospheres of a set of carbon rich AGB stars to improveour understanding of the dynamic processes happening in there.For thefirst time we compare in a systematic way spectrometric, photometric andmid-infrared (VLTI/MIDI) interferometric measurements with differenttype of model atmospheres: (1) hydrostatic models + MOD-dusty models (Groenewegen, 2012) added a posteriori; (2) self-consistent dynamicmodel atmospheres (Eriksson et al. 2014). These allow to interpret in acoherent way the dynamic behavior of gas and dust. In addition, thegeometric model fitting tool for interferometric data GEM-FIND isapplied to carry out a first interpretation of the structuralenvironment of the stars.The results underline that the joint use ofdifferent kind of observations, as photometry, spectroscopy andinterferometry, is essential for understanding and modelingthe atmosphere of pulsating C-rich AGB stars. For our first target, thecarbon-rich Mira star RU Vir, the dynamic model atmospheres fit well theISO/SWS spectra in the wavelength range λ = [2.9, 13.0] μm.However, the object turned out to be “peculiar”: we notice adiscrepancy in the visible part of the SED, and in the visibilities.Possible causes are intra/inter-cycle variations in the dynamic modelatmospheres, and an eventual presence of a companion star and/or disk orclumps in the atmosphere of RU Vir (Rau et al. subm.). Results onfurther targets will also be presented.The increased sample of C-richstars of this work provides crucial constraints for the atmosphericstructure and the formation of SiC. Moreover the second generation VLTIinstrument MATISSE will be a perfect tool to detect and studyasymmetries, as it will allow interferometric imaging in the L, M, and Nbands.

Organisation(en)

Institut für Astrophysik

Externe Organisation(en)

Université Libre de Bruxelles, INAF - Osservatorio Astronomico di Padova, Uppsala Astronomical Observatory (UAO), Royal Observatory of Belgium

Journal

IAU General Assembly Meeting

Band

29

Publikationsdatum

08-2015

ÖFOS 2012

103004 Astrophysik

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/0b36abfc-71a4-4a33-a660-f903b766f4b8