A study of the stellar populations in the Kepler field

University essay from Lunds universitet/Astronomi

Author: Mark O Reilly; [2017]

Keywords: Physics and Astronomy;

Abstract: Studying the formation and evolution of galaxies is a fundamental problem in astronomy that warrants repeated investigation by astronomers. How do spiral galaxies like our own come to have its distinct spiral arms? How do stars and their properties change over time and will they continue to evolve in the same manner? To try and attempt to answer such questions we need to look to our own Galaxy the Milky Way. Models have become an integral part of developing our understanding of the Galaxy but for these models to produce reliable data from which conclusions can be made upon, they must be shown to produce accurate and reasonable results. In this study a population synthesis code that produces synthetic stellar photometric data is compared to two surveys, 2MASS and Pan-STARRS, to analyse properties such as the total number counts and colour distributions. The parameters in the model were then changed in order to investigate how these effected the model's output. It was found from the different catalogues that the number counts from the model returned fewer stars, the amount of which varied with Galactic latitude with better agreement for the 2MASS survey. The colour of the model was then compared and found that for 2MASS the fit was much better than that of Pan-STARRS and that at higher Galactic latitudes the fit was slightly better. Investigating the input parameters to the model found that no change in the age metallicity relation and star formation rate in the thin disk gave any noticeable difference to either number counts or colour distribution, but for the case where no extinction was selected there were small changes in number counts for Pan-STARRS and expected changes in the colour distribution for both surveys. The initial mass function was also changed but it was found that the default Chabrier lognormal function was the best in simulating observed number counts.

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