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Period doubling and chaos in hydrodynamic type-II Cepheid models

projectIuventus+, IP2012 036572
fundingPolish Ministry of Science and Higher Education, MNiSW
PIRadosław Smolec
dates06.2013 - 11.2015, finished

Jump to project highlights, refereed publications, conference contributions, and presentations.

Project Highlights

Bifurcation diagram

In a sequence of hydrodynamic BL Herculis type models (L=const, M=const, Teff varied) we have found a wealth of dynamic behaviours characteristic for deterministic chaos. Bifurcation diagram for the model sequence is presented above. It shows the possible values of maximum radii, Rmax, as a function of model's effective temperature. Many of the phenomena are detected for the first time in the context of pulsating stars. In our models we observe different routes to chaos, crisis bifurcation, stable periodic domains within chaotic bands, type-I and type-III intermittency.

Hydrodynamic BL Her models are similar to other well known physical sytems showing the deterministic chaos. We find close anlogies between our models and even the simplest example of chaos: iteration of the logistic map, i.e. xi+1=kxi(1-xi). Animations below show: (left) the first return map for logistic equation (a plot of xi+1 vs. xi, as a function of k), and (right) first return map for maximum radii in the BL Her models models (a plot of Rmaxi+1 vs. Rmaxi as a function of Teff). Read more in MNRAS paper (PDF, arXiv:1403.4937).

Refereed Publications

Conference Publications

Presentations

  • 2015, Poznań, XXXVII Meeting of the Polish Astronomical Society, 7-10 September; www
    Nonlinear hydrodynamic models of type II Cepheids; poster
  • 2015, Honolulu, IAU XXIX General Assembly, 3-14 August; www
    Nonlinear hydrodynamic models of type II Cepheids; poster
  • 2015, La Laguna, Tenerife, European Week of Astronomy and Space Science, EWASS 2015, 22-26 June; www
    Nonlinear hydrodynamic models of type II Cepheids; poster
  • 2014, Lisbon, The 7th Chaotic Modeling and Simulation International Conference , 7-10 June; www
    Chaos in hydrodynamic models of pulsating BL Her-type stars; contributed talk
  • 2013, Wroclaw, IAU Symposium No. 301: Precision Asteroseismology: Celebration of the Scientific Opus of Wojtek Dziembowski, 19-23 August; www
    Order and chaos in hydrodynamic BL Her models; poster
  • 2013, Warszawa, XXXVI Meeting of the Polish Astronomical Society, 11-14 September; www
    Order and chaos in hydrodynamic BL Her models; poster
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