Chemical evolution of binary stars

Tamajo, Ettore (2009) Chemical evolution of binary stars. Doctoral thesis, Faculty of Science > Department of Physics.

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Abstract

The last decade was characterized by a significant improvement of stellar theoretical models. It was shown that the involving of rotationally induced mixing of stellar material and/or magnetic field, can significantly change the internal stellar structure which then consequently implicates changes in global stellar features and their evolution. Rotational evolutionary stellar models also predict changes regarding the chemical structure of stellar atmospheres. The goal of this doctoral thesis was to test the predictions of new theoretical models. Binary stars are the main source of fundamental stellar parameters (masses, radii and effective temperatures) and therefore are used to calibrate theoretical evolutionary models. Standard procedures of empirical data analysis, especially the spectroscopic ones, are at the limit of possibilities of such tests. This thesis illustrates algorithms and procedures which are to establish new standards of observable analysis and at the same time sets a new way to analyze in detail the abundance of elements in the component atmospheres of binary stellar systems. Three binary systems were chosen with high-mass components, V380 Cyg, V621 Per and V615 Per, of which the first two systems contain the primary component with the nature of giants, and are in an evolved evolutionary phase. The components of these stellar systems are in an ideal evolutionary phase to test new rotational models. An advanced analysis has shown a discrepancy between empirical data and theoretical predictions. The abundance of elements in atmospheres of evolved stellar components has confirmed no difference to the abundances of elements of B stars in the solar neighbourhood. A very important question has been opened regarding the consistency of the comparison of features between single and binary stars. The conclusions of research in this thesis implicates that the properties and evolution of binary stars are different comparing to the ones of single stars already in the early phases of evolution.

Item Type: Thesis (Doctoral thesis)
Keywords: binary system, massive stars, genetic fitting method
Supervisor: Pavlovski, Krešimir
Date: 6 November 2009
Subjects: NATURAL SCIENCES > Physics
Divisions: Faculty of Science > Department of Physics
Depositing User: Gordana Stubičan Ladešić
Date Deposited: 08 Dec 2013 13:38
Last Modified: 29 Oct 2015 08:05
URI: http://digre.pmf.unizg.hr/id/eprint/13

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