Accurate and homogeneous abundance patterns in solar-type stars of the solar neighbourhood: a chemo-chronological analysis

TL;DR

This study provides detailed chemical abundance patterns of 25 solar-type stars, revealing correlations with age and kinematics, and identifying distinct stellar groups with different chemical signatures in the solar neighborhood.

Contribution

It offers a comprehensive chemo-chronological analysis of solar-type stars, including new clustering of stars based on abundance patterns and insights into their chemical evolution.

Findings

Identified four stellar groups with distinct abundance patterns.

Found correlations between certain element ratios and stellar ages.

Observed trends of element ratios increasing or decreasing with stellar age.

Abstract

We report the abundances of C, Na, Mg, Si, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sr, Y, Zr, Ba, Ce, Nd, and Sm in 25 solar-type stars in the solar neighbourhood, and their correlations with ages, kinematics, and orbital parameters. The spectroscopic analysis, based high resolution and high S/N ratio data, was differential to the Sun and applied to atomic line EWs and to C and C2 spectral synthesis. We performed a statistical study using a tree clustering analysis, searching for groups of stars sharing similar abundance patterns. We derived Teff, log(g), and [Fe/H] with errors of 30 K, 0.13 dex, and 0.05 dex, respectively. The average error in [X/Fe] is 0.06 dex. Ages were derived from theoretical HR diagrams and memberships in kinematical moving groups. We identified four stellar groups: with over-solar abundances (<[X/H]> = +0.26 dex), under-solar abundances (<[X/H]> = -0.24 dex), and intermediate values (<[X/H]> = -0.06 and +0.06 dex) but with distinct chemical patterns. Stars sharing solar metallicity, age, and Galactic orbit possibly have non-solar abundance, an effect either of chemical heterogeneity in their natal clouds or migration. A trend of [Cu/Fe] with [Ba/Fe] seems to exist, in agreement with previous claims in the literature, and maybe also of [Sm/Fe] with [Ba/Fe]. No such correlation involving C, Na, Mn, and Zn is observed. [Mg/Fe], [Sc/Fe], and [Ti/Fe] increase with age. [Mn/Fe] and [Cu/Fe] first increase towards younger stars up to the solar age, and then decrease, a result we interpret as possibly related to time-varying yields of SN Ia and the weak s-process. [Sr/Fe], [Y/Fe], [Sr/Mg], [Y/Mg], [Sr/Zn], and [Y/Zn] linearly increase towards younger stars. [Zr/Fe], [Ce/Fe], [Nd/Fe], [Ba/Mg], [Ba/Zn], and [Sr,Y,Ba/Sm] increase but only for stars younger than the Sun. The steepest negative age relation is due to [Ba/Fe], but only for stars younger than the Sun.