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A quasi-time-dependent radiative transfer model of OH104.9+2.4

D. Riechers·Y. Balega·T. Driebe·K. -H. Hofmann·A. B. Men'shchikov·V. I. Shenavrin·G. Weigelt
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Abstract

We investigate the pulsation-phase dependent properties of the circumstellar dust shell (CDS) of the OH/IR star OH104.9+2.4 based on radiative transfer modeling (RTM) using the code DUSTY. Our previous study concerning simultaneous modeling of the spectral energy distribution (SED) and near-infrared (NIR) visibilities (Riechers et al. 2004) has now been extended by means of a more detailed analysis of the pulsation-phase dependence of the model parameters of OH104.9+2.4. In order to investigate the temporal variation in the spatial structure of the CDS, additional NIR speckle interferometric observations in the K' band were carried out with the 6 m telescope of the Special Astrophysical Observatory (SAO). At a wavelength of 2.12 micron the diffraction-limited resolution of 74 mas was attained. Several key parameters of our previous best-fitting model had to be adjusted in order to be consistent with the newly extended amount of observational data. It was found that a simple rescaling of the bolometric flux F_bol is not sufficient to take the variability of the source into account, as the change in optical depth over a full pulsation cycle is rather high. On the other hand, the impact of a change in effective temperature T_eff on SED and visibility is rather small. However, observations, as well as models for other AGB stars, show the necessity of including a variation of T_eff with pulsation phase in the radiative transfer models. Therefore, our new best-fitting model accounts for these changes.

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D. Riechers, Y. Balega, T. Driebe, K. -H. Hofmann, A. B. Men'shchikov, V. I. Shenavrin, G. Weigelt. 2005-06-22. A quasi-time-dependent radiative transfer model of OH104.9+2.4. https://doi.org/10.1051/0004-6361%3A20042135

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