ASPCS
 
Back to Volume
Paper: The Dynamic Atmospheres of Mira Stars: Comparing the CODEX Models to PTI Time Series Observations of TU Andromedae
Volume: 497, Why Galaxies Care about AGB Stars III: A Closer Look in Space and Time
Page: 117
Authors: Hillen, M.; Verhoelst, T.; Degroote, P.; Acke, B.; Van Winckel, H.
Abstract: We present our already-published evaluation of the effectiveness of the CODEX models, released in 2011, in representing the atmospheres of M-type Mira variables. We present a high-precision interferometric K-band time series of TU And, consisting of 50 nights that cover eight consecutive pulsation cycles. At each phase, the flux at 2.2μm was obtained, along with the spectral shape and visibility points in five channels across the K band. We show a comparison between these data and the dynamical self-excited CODEX model which gives the closest match in stellar parameters yet available. Both the spectrum and the visibilities are consistently reproduced around visual minimum phases. Near the maximum phases, however, the current models predict a photosphere that is too hot and compact, surrounded by an extended atmosphere that lacks H2O opacity, compared to the observations. A better coverage in the model parameter space is needed to make firm conclusions as to the cause of the discrepancies. In the case of TU And, the discrepancy might be lifted by adopting a lower value of the mixing length parameter combined with an increased stellar mass and/or a decreased metallicity.
Back to Volume