BACCHUS Analysis of Weak Lines in APOGEE Spectra (BAWLAS)

TL;DR

This paper presents a new catalog of precise chemical abundances for weak and blended spectral lines in stellar spectra, derived using an improved analysis method, enabling better insights into stellar and galactic evolution.

Contribution

The authors develop and apply an enhanced version of the BACCHUS code to measure weak and blended spectral features, creating a comprehensive catalog that surpasses previous abundance measurements in APOGEE spectra.

Findings

Catalog includes ~120,000 giants with detailed abundances of Na, P, S, V, Cu, Ce, Nd, and isotopic ratios.

The new measurements agree well with literature and improve upon existing APOGEE abundances.

Demonstrated applications include identifying stars with enhanced s-process elements and studying red giant branch mixing.

Abstract

Elements with weak and blended spectral features in stellar spectra are challenging to measure and require specialized analysis methods to precisely measure their chemical abundances. In this work, we have created a catalog of approximately 120,000 giants with high signal-to-noise APOGEE DR17 spectra, for which we explore weak and blended species to measure Na, P, S, V, Cu, Ce, and Nd abundances and $^{12}$C/$^{13}$C isotopic ratios. We employ an updated version of the BACCHUS (Brussels Automatic Code for Characterizing High accUracy Spectra) code to derive these abundances using the stellar parameters measured by APOGEE's DR17 ASPCAP pipeline, quality flagging to identify suspect spectral lines, and a prescription for upper limits. Combined these allow us to provide our BACCHUS Analysis of Weak Lines in APOGEE Spectra (BAWLAS) catalog of precise chemical abundances for these weak and blended species that agrees well with literature and improves upon APOGEE abundances for these elements, some of which are unable to be measured with APOGEE's current, grid-based approach without computationally expensive expansions. This new catalog can be used alongside APOGEE and provide measurements for many scientific applications ranging from nuclear physics to Galactic chemical evolution and Milky Way population studies. To illustrate this we show some examples of uses for this catalog, such as, showing that we observe stars with enhanced s-process abundances or that we can use the our $^{12}$C/$^{13}$C ratios to explore extra mixing along the red giant branch.