Chemical evolution of ytterbium in the Galactic disk
Research output: Contribution to journal › Journal article › Research › peer-review
Standard
Chemical evolution of ytterbium in the Galactic disk. / Montelius, M.; Forsberg, R.; Ryde, N.; Jönsson, H.; Afsar, M.; Johansen, A.; Kaplan, K. F.; Kim, H.; Mace, G.; Sneden, C.; Thorsbro, B.
In: Astronomy & Astrophysics, Vol. 665, A135, 2022.Research output: Contribution to journal › Journal article › Research › peer-review
Harvard
APA
Vancouver
Author
Bibtex
}
RIS
TY - JOUR
T1 - Chemical evolution of ytterbium in the Galactic disk
AU - Montelius, M.
AU - Forsberg, R.
AU - Ryde, N.
AU - Jönsson, H.
AU - Afsar, M.
AU - Johansen, A.
AU - Kaplan, K. F.
AU - Kim, H.
AU - Mace, G.
AU - Sneden, C.
AU - Thorsbro, B.
PY - 2022
Y1 - 2022
N2 - Context. 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, only the s-process-dominated element cerium has been accurately measured for a large sample of disk stars from the infrared H band. The more r-process dominated element ytterbium has only been measured in a small subset of stars so far.Aims. In this study we aim to measure the ytterbium (Yb) abundance of local disk giants using the Yb II line at lambda(air) = 16 498 angstrom. We also compare the resulting abundance trend with cerium and europium abundances for the same stars to analyse the s- and r-process contributions.Methods. 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 via the same method, but it was not possible to determine the abundance of Yb from those spectra due to blending issues for stars with [Fe/H] > -1. In the present analysis, we utilise the stellar parameters determined from the optical analysis.Results. We determined the Yb abundances with an estimated uncertainty for [Yb/Fe] of 0.1 dex. By comparison, we found that the [Yb/Fe] trend closely follows the [Eu/Fe] trend and has clear s-process enrichment in identified s-rich stars. This comparison confirms both that the validity of the Yb abundances is ensured and that the theoretical prediction that the s-/r-process contribution to the origin of Yb of roughly 40/60 is supported.Conclusions. 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.
AB - Context. 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, only the s-process-dominated element cerium has been accurately measured for a large sample of disk stars from the infrared H band. The more r-process dominated element ytterbium has only been measured in a small subset of stars so far.Aims. In this study we aim to measure the ytterbium (Yb) abundance of local disk giants using the Yb II line at lambda(air) = 16 498 angstrom. We also compare the resulting abundance trend with cerium and europium abundances for the same stars to analyse the s- and r-process contributions.Methods. 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 via the same method, but it was not possible to determine the abundance of Yb from those spectra due to blending issues for stars with [Fe/H] > -1. In the present analysis, we utilise the stellar parameters determined from the optical analysis.Results. We determined the Yb abundances with an estimated uncertainty for [Yb/Fe] of 0.1 dex. By comparison, we found that the [Yb/Fe] trend closely follows the [Eu/Fe] trend and has clear s-process enrichment in identified s-rich stars. This comparison confirms both that the validity of the Yb abundances is ensured and that the theoretical prediction that the s-/r-process contribution to the origin of Yb of roughly 40/60 is supported.Conclusions. 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.
KW - stars: abundances
KW - stars: late-type
KW - Galaxy: abundances
KW - Galaxy: disk
KW - Galaxy: evolution
KW - infrared: stars
KW - NEUTRON-CAPTURE ELEMENTS
KW - STARS
KW - LINE
KW - CE
KW - IDENTIFICATION
KW - SPECTROGRAPH
KW - ABUNDANCES
KW - ENRICHMENT
KW - CERIUM
KW - RICH
U2 - 10.1051/0004-6361/202243140
DO - 10.1051/0004-6361/202243140
M3 - Journal article
VL - 665
JO - Astronomy & Astrophysics
JF - Astronomy & Astrophysics
SN - 0004-6361
M1 - A135
ER -
ID: 322269721