The consistency of chemical clocks among coeval stars
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Date
2021
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Abstract
The abundance ratios of some chemical species have been found to correlate with
stellar age, leading to the possibility of using measurements of abundances in stellar
atmospheres as age indicators thanks to the Galactic chemical evolution. These chemical
clocks have been calibrated with solar-twins, open clusters and red giants, however, how
effective they are in identifying coeval systems has not been tested for populations that
sample a broader parameter space. In that sense, wide binary systems are the perfect
objects to assess the applications of chemical clocks, because their components have a
common origin and are separated by great distances, so they should not interact with
each other, and their abundances and ages are expected to be consistent. In this thesis,
I determined the abundances of a sample of 5 wide binaries and collected data for other
31 systems from the literature in order to test the applicability of chemical clocks. I
found that wide binaries have more consistent abundances than random pairs. I also
found that chemical clocks are even more consistent among the components of wide
binaries than their [X/Fe] ratios. Not only that, but the special case of the pair HIP
34426/HIP 34407 would indicate that chemical clocks are consistent for coeval stars
even when their abundances are not. Finally, given the evidence that chemical clocks
trace information about stellar birthplaces and chemical evolution, I briefly studied their
benefits for chemical tagging by using them to reconstruct a sample of 3 open clusters,
and found that chemical clocks do not improve the identification of the cluster’s members,
but could be used for decontamination. Despite this, the results are limited by the age
range of the sample, and there is still much work that could be done to better evaluate
this idea and find more applications for chemical clocks.
Description
Tesis (Master in Astrophysics)--Pontificia Universidad Católica de Chile, 2021