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

TL;DR

This study investigates how the number of spectral lines influences the measurement of element abundances in stars, identifying optimal elements for chemical tagging and proposing a weighted mean method for abundance calculation.

Contribution

It introduces a weighted mean approach for abundance estimation that accounts for line deviations and compares the intrinsic scatter of different elements for chemical tagging.

Findings

Weighted mean effectively reduces outlier influence.

Similar star-to-star scatter for iron group and alpha elements when using same line numbers.

Cr and Ni show the smallest scatter, Al the largest.

Abstract

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 minimize 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.