Galactic Chemical Evolution Signatures in Stellar Atmospheres and Their Possible Planetary Connection

Nickson, Elena (2016). Galactic Chemical Evolution Signatures in Stellar Atmospheres and Their Possible Planetary Connection. PhD thesis The Open University.

DOI: https://doi.org/10.21954/ou.ro.0000ef7c

Abstract

In recent years there have been many studies to determine whether there is a chemical signature in stellar atmospheres that can be linked to the presence of planets. Most of these studies have involved bulk analysis of stars to identify whether planet-hosting stars have a higher metallicity than non planet-hosting stars. These studies led to the work of Meléndez et al. [49], which identified a signature in the solar photosphere which was likely caused by the presence of planets.

To further explore this theory, I obtained high-quality spectra from the ESPaDOnS spectropolarimeter at the CFHT for 10 stars with similar stellar parameters (effective temperature, surface gravity, microturbulence velocity and metallicity). I performed a differential abundance analysis on the planet-hosting star 61 Vir against 9 comparison stars. This analysis indicated that there is no planetary signature present in 61 Vir but instead, that there is a signature observed when performing the same analysis on an individual star basis, which is observable with age. I determined the relative ages of the stars and then perform a differential abundance analysis of 9 stars using a younger tenth star as reference. From this I found likely evidence of galactic chemical evolution in the stellar atmospheres.

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