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Identifying the best iron-peak and alpha-capture elements for chemical tagging: The impact of the number of lines on measured scatter

Vardan Zh. Adibekyan

The main goal of this work is to explore which elements carry the most information about the birth origin of stars and as such that are best suited for chemical tagging. We explored different techniques to minimise the effect of outlier value lines in the abundances by using Ni abundances derived for 1111 FGK type stars. We evaluated how the limited number of spectral lines can affect the final chemical abundance. Then we were able to make an efficient even footing comparison of the [X/Fe] scatter between the elements that have different number of observable spectral lines in the studied spectra.
We found that the most efficient way of calculating the average abundance of elements when several spectral lines are available is to use a weighted mean (WM) where as a weight we considered the distance from the median abundance. This method can be effectively used without removing suspected outlier lines.We showed that when the same number of lines is used to determine chemical abundances, the [X/Fe] star-to-star scatter for iron group and alpha-capture elements is almost the same. On top of this, but at a lower level the largest scatter was observed for Al and the smallest for Cr and Ni.
We recommend caution when comparing [X/Fe] scatters among elements that have a different number of spectral lines available. A meaningful comparison is necessary to identify elements that show the largest intrinsic scatter and can be thus used for chemical tagging.

2015 October 29, 15:00

Observatório Astronómico de Lisboa (Seminar room)
Tapada da Ajuda, 1349-018 Lisboa

Faculdade de Ciências da Universidade de Lisboa Universidade do Porto Faculdade de Ciências e Tecnologia da Universidade de Coimbra
Fundação para a Ciência e a Tecnologia COMPETE 2020 PORTUGAL 2020 União Europeia