A statistical method for the identification of stars enriched in neutron-capture elements from medium-resolution spectra

TL;DR

This paper introduces an automated statistical method to identify stars with high neutron-capture element content using medium-resolution spectra, tested on a large stellar sample from the SEGUE survey, focusing on europium lines.

Contribution

The study develops a novel automated approach for detecting neutron-capture element enrichment in stars from medium-resolution spectra, enhancing efficiency over manual methods.

Findings

Identified stars with potential neutron-capture enrichment in large stellar samples.

Detected significant neutron-capture element signatures in globular cluster M3.

Approximately 15% of stars in M3 may be rich in heavy nuclides.

Abstract

We present an automated statistical method that uses medium-resolution spectroscopic observations of a set of stars to select those that show evidence of possessing significant amounts of neutron-capture elements. Our tool was tested against a sample of $\sim 70,000$ F- and G-type stars distributed among $215$ plates from the Galactic Understanding and Exploration (SEGUE) survey, including $13$ that were directed at stellar Galaxy clusters. Focusing on five spectral lines of europium in the visible window, our procedure ranked the stars by their likelihood of having enhanced content of this atomic species and identifies the objects that exhibit signs of being rich in neutron-capture elements as those scoring in the upper $2.5\%$. We find that several of the cluster plates contain relatively large numbers of stars with significant absorption around at least three of the five selected lines. The most prominent is the globular cluster M3, where we measured a fraction of stars that are potentially rich in heavy nuclides, representing at least $15\%$.