ISO-SWS Spectra of Carbon- and Oxygen-Rich AGB Stars

Author(s): Bernhard Aringer, Josef Hron, Franz Kerschbaum, Rita Loidl, Susanne Höfner, W Windsteig
Abstract: The ISO-SWS spectra of several representative carbon- and oxygen-rich AGB variables (R Aql, R Cas, T Dra, V Cyg, V CrB and R Scl) were obtained at several phases of their pulsational cycle. This allows us to study the molecular features and the dust emission of these objects as a function of stellar parameters as well as pulsational phase. The observational data are compared with synthetic molecular spectra based on hydrostatic models (MARCS) and on dynamical atmospheres, which include such phenomena as pulsation, mass loss and dust formation. Opacities of CO, CN, C₂, C₃, C₂H₂, HCN, SiO, H₂O, TiO, OH and CO₂ have been taken into account. As it turns out, a complete treatment of molecular opacities including a large number of lines of species like C₃, C₂H₂, HCN, H₂O and TiO is crucial for the construction of model atmospheres, the interpretation of dust features and the appearance of the pseudo-continuum. Some aspects of the SWS spectra like their variations can only be explained by dynamical atmospheres. To be able to analyse also the targets with significant mass loss, we included a dust component in the synthetic spectra. The dust component either comes directly from the dynamical models or is modelled with the DUSTY code. On the basis of these synthetic spectra we also investigate the influence of molecular features on the interpretation of the dust emission and vice versa. This is of special importance in the 8 to 16 micron region. This work was supported by the Austrian Science Fund project S7308-AST. FK is supported by APART (Austrian Academy of Sciences).
Organisation(s): Department of Astrophysics
External organisation(s): Uppsala University, University of Vienna
Journal: Astronomische Gesellschaft Abstract Series
Volume: 14
Pages: 48
ISSN: 0934-4438
Publication date: 1998
Austrian Fields of Science 2012: 103003 Astronomy, 103004 Astrophysics
Portal url: https://ucrisportal.univie.ac.at/en/publications/98bf37f3-0be6-4094-ad3a-44527f60c910

Back