The Gaia-ESO Survey: Lithium enrichment histories of the Galactic thick and thin disc

Abstract

Lithium abundance in most of the warm metal-poor main sequence stars shows a constant plateau (A(Li) ∼ 2.2 dex) and then the upper envelope of the lithium vs. metallicity distribution increases as we approach solar metallicity. Meteorites, which carry information about the chemical composition of the interstellar medium at the solar system formation time, show a lithium abundance A(Li)∼ 3.26 dex. This pattern reflects the Li enrichment history of the interstellar medium during the Galaxy lifetime. After the initial Li production in Big Bang Nucleosynthesis, the sources of the enrichment include AGB stars, low-mass red giants, novae, type II supernovae, and Galactic cosmic rays. The total amount of enriched Li is sensitive to the relative contribution of these sources. Thus different Li enrichment histories are expected in the Galactic thick and thin disc. We investigate the main sequence stars observed with UVES in Gaia-ESO Survey iDR4 catalog and find a Li-[α/Fe] anticorrelation independent of [Fe/H] , T eff , and log(g) . Since in stellar evolution different α enhancements at the same metallicity do not lead to a measurable Li abundance change, the anticorrelation indicates that more Li is produced during the Galactic thin disc phase than during the Galactic thick disc phase. We also find a correlation between the abundance of Li and s-process elements Ba and Y, and they both decrease above the solar metallicity, which can be explained in the framework of the adopted Galactic chemical evolution models.

High-resolution Spectroscopic Study of Dwarf Stars in the Northern Sky: Lithium, Carbon, and Oxygen Abundances

“…A(Li) is predominantly higher among hotter and more massive stars. This main trend is in agreement with results of previous studies (see, e.g., Ramírez et al 2012;Luck 2017;Bensby & Lind 2018;Fu et al 2018;Pavlenko et al 2018). However, there are stars with the same atmospheric parameters and ages but different lithium abundances.…”

“…Recent high-resolution spectroscopic surveys of the Milky Way disk have reported that lithium abundances in the solar neighborhood decrease at supersolar metallicities. Delgado Mena et al (2015) were some of the first to show that the 7 Li abundance decreases with [Fe/H] > 0 and later works by Guiglion et al (2016) in the AMBRE project, Fu et al (2018) in the Gaia-ESO Survey, and Bensby & Lind (2018) from combined data of various spectrographs (e.g., FEROS and MIKE) confirmed this result. The studies by Guiglion et al (2016) and Prantzos et al (2017) tried to explain the 7 Li decreases at supersolar metallicities with stellar migration.…”

“…Every new analysis of these chemical elements in stellar atmospheres contributes to the ongoing discussion of their importance in understanding the Galaxy evolution and whether they constitute a star-planet connection (see, e.g., Delgado Mena et al 2010;González Hernández et al 2010;Brugamyer et al 2011;Petigura & Marcy 2011;Schuler et al 2011;Ramírez et al 2012;Spina et al 2016;Luck 2017;Adibekyan et al 2018;Bensby & Lind 2018;Fu et al 2018;Luck 2018a;Nissen & Gustafsson 2018;Guiglion et al 2019;Pavlenko et al 2019).…”

Evolution of lithium in the Milky Way halo, discs, and bulge

“…A bending of the Spite plateau below [Fe/H] ∼ -3 is clearly present in the data of Sbordone et al (2010). For the discs, we adopt the recent spectroscopic data from the AMBRE Project (Guiglion et al 2016) and GES (Fu et al 2018), where a distinction is made between thick and thin disc stars, basing on chemical criteria. The AMBRE catalogue consists of Li abundances for 7300 stars, homogeneously derived from high-resolution spectra in the ESO archive with an automatic method (see Guiglion et al 2016 for a description of the method and of the data validation).…”

“…Lodders et al 2009) and young T Tauri stars (Bonsack & Greenstein 1960). To make the story a bit more complicated, a huge dispersion in Li abundances is observed for stars at disc metallicities (see Ramirez et al 2012;Delgado Mena et al 2015;Guiglion et al 2016;Fu et al 2018, among others, for recent work), while observations of extremely metal-poor stars (Sbordone et al 2010;Melendez et al 2010;Hansen et al 2014;Bonifacio et al 2015) find the Spite plateau to bend down for stars with [Fe/H]<-2.8 dex. In this work, we do not consider the first problem (the so-called cosmological Li problem).…”