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The influence of the stellar mass-loss on the dynamics of star clusters
Dinnbier, František ; Jungwiert, Bruno (advisor) ; Šubr, Ladislav (referee)
This work aims at studying the influence of the stellar mass-loss, resulting from the stellar evolution, on the dynamics of massive star clusters. The emphasis has been put on the mass-loss by low-mass and intermediate-mass stars (m < 8 Mo) that form, at the end of their life, a planetary nebula. The expansion speed of gas released by these stars is lower than the escape speed from sufficiently massive star clusters, and the gas can be retained by the cluster. For modelling of the gas hydrodynamics, a simple sticky-particles method was used. To carry out simulations in which gaseous and stellar particles mutually interact through their gravity, substantial modifications had to be realized in the N-body codes Nbody6 and Hermit. For the sake of comparing the influence of stellar mass-loss and relaxation processes, which are happening in the simplified model, two types of simulations were performed: one with the formation of gaseous particles and the other consisting of purely stellar component. The simulations in which the gas component was present showed out a significantly different evolution in the central part of the cluster than those in which the presence of gas was not considered.
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Stellar mass-loss in the dynamics of galaxies
Křížek, Miroslav
Title: Stellar mass-loss in galactic dynamics Author: Miroslav Křížek Department: Astronomical Institute of the Charles University Supervisor: RNDr. Bruno Jungwiert, Ph.D., Astronomical Institute - Academy of Sciences of the Czech Republic, v.v.i. and University of California - Riverside Supervisor's e-mail address: bruno@ig.cas.cz Abstract: We present an implementation of the statistical approach to the stars-gas mass exchange cycle into the N-body code. First, we summarize available data on stellar mass-loss and derive the time-dependency of the mass-loss rate of a single stellar population. Since the adopted probabilistic scheme that served as a basis for our implementation was limited to the linear star formation law while observations seem to suggest a non-linearity, we derive the non-linear star formation scheme. Both sides of the mass exchange cycle are then implemented into the code with stellar and gaseous particles and compared with an analytic recipe to test their reliability. In the next step, the comparison of such an extended statistical approach with deterministic scheme is performed for a fully dynamical model. The aim of such comparison is to explore divergence between both models of different natures. As illustration of the code application and sensitivity of the resulting galaxy disk...
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Stellar mass-loss in the dynamics of galaxies
Křížek, Miroslav
Title: Stellar mass-loss in galactic dynamics Author: Miroslav Křížek Department: Astronomical Institute of the Charles University Supervisor: RNDr. Bruno Jungwiert, Ph.D., Astronomical Institute - Academy of Sciences of the Czech Republic, v.v.i. and University of California - Riverside Supervisor's e-mail address: bruno@ig.cas.cz Abstract: We present an implementation of the statistical approach to the stars-gas mass exchange cycle into the N-body code. First, we summarize available data on stellar mass-loss and derive the time-dependency of the mass-loss rate of a single stellar population. Since the adopted probabilistic scheme that served as a basis for our implementation was limited to the linear star formation law while observations seem to suggest a non-linearity, we derive the non-linear star formation scheme. Both sides of the mass exchange cycle are then implemented into the code with stellar and gaseous particles and compared with an analytic recipe to test their reliability. In the next step, the comparison of such an extended statistical approach with deterministic scheme is performed for a fully dynamical model. The aim of such comparison is to explore divergence between both models of different natures. As illustration of the code application and sensitivity of the resulting galaxy disk...
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The influence of the stellar mass-loss on the dynamics of star clusters
Dinnbier, František ; Jungwiert, Bruno (advisor) ; Šubr, Ladislav (referee)
This work aims at studying the influence of the stellar mass-loss, resulting from the stellar evolution, on the dynamics of massive star clusters. The emphasis has been put on the mass-loss by low-mass and intermediate-mass stars (m < 8 Mo) that form, at the end of their life, a planetary nebula. The expansion speed of gas released by these stars is lower than the escape speed from sufficiently massive star clusters, and the gas can be retained by the cluster. For modelling of the gas hydrodynamics, a simple sticky-particles method was used. To carry out simulations in which gaseous and stellar particles mutually interact through their gravity, substantial modifications had to be realized in the N-body codes Nbody6 and Hermit. For the sake of comparing the influence of stellar mass-loss and relaxation processes, which are happening in the simplified model, two types of simulations were performed: one with the formation of gaseous particles and the other consisting of purely stellar component. The simulations in which the gas component was present showed out a significantly different evolution in the central part of the cluster than those in which the presence of gas was not considered.
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