M giants with IGRINS IV. Identification and characterization of a near-IR line of the s-element Barium

Abstract

Neutron-capture elements represent an important nucleosynthetic channel in the study of the Galactic Chemical Evolution of stellar populations. For stellar populations behind significant extinction, such as those in the Galactic Center and along the Galactic plane, abundance analyses based on near-IR spectra are necessary. Previously, spectral lines from the neutron-capture elements such as copper (Cu), cerium (Ce), neodymium (Nd), and ytterbium (Yb) have been identified in the H band, while yttrium (Y) lines have been identified in the K band. Due to the scarcity of spectral lines from neutron-capture elements in the near-IR, the addition of useful spectral lines from other neutron-capture elements is highly desirable. The aim of this work is to identify and characterise a spectral line suitable for abundance determination from the most commonly used s-process element, namely barium. We observed near-IR spectra of 37 M giants in the solar neighbourhood at high S/N and high spectral resolution using the IGRINS spectrometer on the GEMINI South telescope. Using a manual spectral synthesis method, we determined the stellar parameters for these stars and derived the barium abundance from the Ba line (6s5d ${}^3$D${}_2\to$ 6s6p ${}^3$P${}_2^o$) at ${\lambda }_{\mathrm{air}}=23253.56$Å in the K band. We demonstrate that the Ba line in the K band at 2.33\,\mic\ ($\lambda$23253.56) is useful for abundance analysis from spectra of M giants. The line becomes progressively weaker at higher temperatures and is only useful in M giants and the coolest K giants at supersolar metallicities. We can now add Ba to the trends of the heavy elements Cu, Zn, Y, Ce, Nd, and Yb, which can be retrieved from high-resolution H- and K-band spectra. This opens up the study of nucleosynthetic channels, including the s-process and the r-process, in dust-obscured populations such as the Galactic Center.

9 pages, 6 figures, Accepted for publication A&A

References in corpus (16)

• The NumPy array: a structure for efficient numerical computation
• The Astropy Project: Sustaining and Growing a Community-oriented Open-source Project and the Latest Major Release (v5.0) of the Core Package
• A grid of MARCS model atmospheres for late-type stars I. Methods and general properties
• Galactic Chemical Evolution and solar s-process abundances: dependence on the 13C-pocket structure
• Chemical abundances of 1111 FGK stars from the HARPS GTO planet search program II: Cu, Zn, Sr, Y, Zr, Ba, Ce, Nd and Eu
• BACCHUS Analysis of Weak Lines in APOGEE Spectra (BAWLAS)
• On the origin of the Galactic thin and thick discs, their abundance gradients and the diagnostic potential of their abundance ratios
• Abundances of neutron-capture elements in thin- and thick-disc stars in the solar neighbourhood
• Fluorine in the solar neighborhood: modelling the Galactic thick and thin discs
• The Galactic Chemical Evolution of phosphorus observed with IGRINS
• Chemical Evolution of Ytterbium in the Galactic Disk
• Chemical Abundances Of Open Clusters From High-Resolution Infrared Spectra. II. NGC 752
• Chemical Abundances Of Open Clusters From High-Resolution Infrared Spectra. I. NGC 6940
• M giants with IGRINS I. Stellar parameters and $\alpha$-abundance trends of the solar neighborhood population
• M Giants with IGRINS II. Chemical Evolution of Fluorine at High Metallicities
• Effective Temperature Estimations from Line Depth Ratios in the \H\ and \K-band Spectra of IGRINS