Um estudo do parâmetro de viscosidade do disco da estrela Be ABE A26

Abstract

Although viscosity plays a fundamental role in the diffusion of astrophysical disks, we are still unable to derive its properties theoretically from first principles. Therefore, the search for observational constraints on its behavior represents an important step towards its understanding. In this work, we investigated the viscosity parameter (α) of the disk around the Be star ABE A26 (MWC 109), to place empirical constraints on it and examine its temporal variability. We used the star’s spectral energy distribution (SED) and photometric data from the KELT project. By fitting the SED, we determined stellar parameters such as mass, equatorial-to-polar radius ratio, distance, among other parameters relevant to disk modeling. These fits yielded values consistent with the literature, including a mass of 10.0 ± 1.0M⊙ and a radius ratio of 1.36±0.20. We then modeled the light curve at six different epochs of disk formation/dissipation using simulated disk scenarios with the hydrodynamic code SINGLEBE. The main results of this analysis include values of logα between 0.15 and 0.55, and logΣ0[g cm−2 ] (disk base density) between −0.40 and 0.87. The viscosity parameter values found are slightly higher than those typically reported in the literature, which may be a consequence of the short disk development timescales. As future work, we intend to study the initial outbursts of this object observed by KELT, whose early magnitudes are brighter than those of the events analyzed here. Finally, we plan to apply the methodology developed in this study to the full sample of Be stars observed by the KELT mission, and, eventually, to other observational surveys.