Spectroscopic Age Indicators in Giant Stars

Overview

This study investigated the use of abundance ratios such as [Y/Mg], [Y/Al], [Y/Si], [Y/Ca], and [Y/Ti] as stellar age indicators in giant stars from open clusters.

We analyzed spectra of 50 giant stars in seven open clusters using the FEROS spectrograph to evaluate the relationship between chemical abundance and stellar age.

While some indicators like [Y/Mg] show a correlation with age, we observed greater scatter in giants compared to dwarf stars, suggesting that the use of these indicators requires caution.

Methodology

Selection of open clusters with known ages between 0.1–6.9 Gyr
High-resolution spectroscopy with FEROS (R~48,000)
Abundance analysis with MOOG and MARCS models
Computation of [Y/X] ratios for Mg, Al, Si, Ca, and Ti

Main Results

[Y/Mg], [Y/Al], and [Y/Si] show decreasing trends with age
[Y/Ca] and [Y/Ti] do not show significant correlations
Scatter is larger than that found in thin-disk dwarf stars
Correlations depend on stellar mass and evolutionary stage

We conclude that chemical age indicators can be used in giant stars, but with caution, due to significantly increased dispersion compared to dwarfs.

Correlation between abundance and age — Example of the correlation between [Y/X] and the age of the analyzed open clusters (black triangles), field giants (grey squares) as well as the field dwarfs (open squares).

How to Cite

Katime Santrich, O. J., Kerber, L., Abuchaim, Y., & Gonçalves, G. (2022). On the validity of the spectroscopic age indicators [Y/Mg],[Y/Al],[Y/Si],[Y/Ca], and [Y/Ti] for giant stars. Monthly Notices of the Royal Astronomical Society, 514(4), 4816–4827.
Title: On the validity of the spectroscopic age indicators [Y/Mg],[Y/Al],[Y/Si],[Y/Ca], and [Y/Ti] for giant stars
DOI: 10.1093/mnras/stac1183

Collaborators: University of São Paulo, University of Campinas, Federal University of São Paulo