Chemical Evolution of Ytterbium in the Galactic Disk

Abstract

Measuring the abundances of neutron-capture elements in Galactic disk stars is an important part of understanding key stellar and galactic processes. In the optical wavelength regime a number of different neutron-capture elements have been measured, however from the infrared H-band only the s-process dominated element cerium has been accurately measured for a large sample of disk stars. The more r-process dominated element ytterbium has only been measured in a small subset of stars so far. In this study we aim to measure the ytterbium (Yb) abundance of local disk giants using the Yb II line at ${\lambda }_{\text{air}}$=16498Å. We also compare the resulting abundance trend with Ce and Eu abundances for the same stars to analyse the s- and r-process contributions. We analyse 30 K-giants with high-resolution H-band spectra using spectral synthesis. The very same stars have already been analysed using high-resolution optical spectra using the same method, but the abundance of Yb was not possible to determine from those spectra due to blending issues for stars with [Fe/H]>-1. In this present analysis, we utilise the stellar parameters determined from the optical analysis. We determined the Yb abundances with an estimated uncertainty for [Yb/Fe] of 0.1 dex. From comparison, the trend of [Yb/Fe] follows closely the [Eu/Fe] trend and has clear s-process enrichment in identified s-rich stars. From the comparison, both the validity of the Yb abundances are ensured, and the theoretical prediction of a roughly 40/60 s-/r-process contribution to Yb's origin is supported. These results show that with a careful and detailed analysis of infrared spectra, reliable Yb abundances can be derived for a wider sample of cooler giants in the range -1.1<[Fe/H]<0.3. This is promising for further studies of the production of Yb and for the r-process channel, key for Galactochemical evolution, in the infrared.

Accepted for publication in A&A. 11 pages, 7 figures

References in corpus (20)

• GW170817: Observation of Gravitational Waves from a Binary Neutron Star Inspiral
• A grid of MARCS model atmospheres for late-type stars I. Methods and general properties
• Light Curves of the Neutron Star Merger GW170817/SSS17a: Implications for R-Process Nucleosynthesis
• The Emergence of a Lanthanide-Rich Kilonova Following the Merger of Two Neutron Stars
• The Dawes Review 2: Nucleosynthesis and stellar yields of low and intermediate-mass single stars
• A Search for Stars of Very Low Metal Abundance. VI. Detailed Abundances of 313 Metal-Poor Stars
• First Stars VIII -- Enrichment of the neutron-capture elements in the early Galaxy
• Galactic Chemical Evolution and solar s-process abundances: dependence on the 13C-pocket structure
• The elemental composition of the Sun III. The heavy elements Cu to Th
• New Rare Earth Element Abundance Distributions for the Sun and Five r-Process-Rich Very Metal-Poor Stars
• Line lists for the A2PI-X2Sigma+ (red) and {B2Sigma+-X2Sigma} (violet) Systems of CN, 13C14N, and 12C15N, and Application to Astronomical Spectra
• The APOGEE Data Release 16 Spectral Line List
• The role of neutron star mergers in the chemical evolution of the Galactic halo
• New Detections of Arsenic, Selenium, and Other Heavy Elements in Two Metal-Poor Stars
• Evidence for $\gtrsim 4$ Gyr timescales of neutron star mergers from Galactic archaeology
• Abundances of disk and bulge giants from high-resolution optical spectra -- IV. Zr, La, Ce, Eu
• Abundances of disk and Bulge giants from high-resolution optical spectra III. Sc, V, Cr, Mn, Co, Ni
• Modelling the chemical evolution of Zr, La, Ce and Eu in the Galactic discs and bulge
• 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

Cited by in corpus (10)

• The Galactic Chemical Evolution of phosphorus observed with IGRINS
• 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
• Detailed $\alpha$ abundance trends in the inner Galactic bulge
• Exploring fluorine chemical evolution in the Galactic disk: the open cluster perspective
• Abundances of disk and bulge giants from high-resolution optical spectra V. Molybdenum -- the p-process element
• M giants with IGRINS IV. Identification and characterization of a near-IR line of the s-element Barium
• The first r-process enhanced star confirmed to be a member of the Galactic bulge
• Cepheid Metallicity in the Leavitt Law (C--MetaLL) survey: VIII. High-Resolution IGRINS Spectroscopy of 23 Classical Cepheids: Validating NIR Abundances
• A Near-Infrared and Optical Study of NGC 5822: An Open Cluster Hosting Barium-stars and Lithium-Enriched Giant Stars