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Bestimmung der Bahnelemente von extrasolaren Planeten aufgrund von Radialgeschwindigkeitsmessdaten mittels EvolutionAlgorithmen
| Content Provider | Semantic Scholar |
|---|---|
| Author | Chwatal, Andreas M. |
| Copyright Year | 2006 |
| Abstract | About one decade ago, the first planet outside our solar system was discovered. Since then, the amount of known systems has increased to more than 150. The rate of the discovery of new planets is increasing more and more. Presently more than one exoplanet per month is discovered on average. Although there exist various methods of planet-discovery (astrometry, transit method, direct imaging) the radial velocity method seems to be the most successful method. Almost all planetary systems have been discovered in that way. The radial velocity method is based on the fact that planet and star both move around the barycenter of the system. The motion of the star is very low because in contrast to the planet the star has a very high mass. With high precision measurements it is possible to detect the radial component of this motion. This radial velocity measurements lead to the determination of the orbital elements of the planet. Usual data reduction methods are primarily based on the Fourier analysis. Applying the Discrete Fourier Transform to the data points yields the dominating frequencies. Taking this frequencies, a sine is fitted to the data points whereby only circular orbits can be explained. To find solutions for excentric orbits, some adjustments have to be done. Due to this iterative process it is not guaranteed, that this vector of parameters is really the global optimum of the optimization problem. Given a planetary system with more than one planet, the usual approach is to find a solution for the planet with the highest mass. This solution is then subtracted from the data sample, and the remaining signal is then processed as described before. The disadvantage of this procedure is that errors in the first solution propagate through every solution for further planets. In this thesis an alternative approach to the data reduction, namely a (µ, λ)-Evolution Strategy which falls in the category of Evolutionary Algorithms, is presented. The most important advantage is to overcome the shortcoming of the traditional Fourier-based method to favor circular planetary orbits. Further planets in a system are less biased with preceding (higher mass) planet-solutions than with the Fourier-approach. When increasing the size of the population and the mutation-rate, it is increasingly possible to find good solutions, even for more complex systems. The successful application to well explored systems clearly demonstrated the possibilities of this approach. The analysis of currently not determined systems provided … |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://publik.tuwien.ac.at/files/pub-inf_4476.pdf |
| Alternate Webpage(s) | https://publik.tuwien.ac.at/files/pub-inf_4476.pdf |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
