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The investigation of the metal-poor tail in the Galactic bulge provides unique information on the early Milky Way assembly and evolution. A chemo-dynamical analysis of 17 very metal-poor stars (VMP, [Fe/H] $<-2.0$) selected from the…

We present chemical abundances for 21 elements (from Li to Eu) in 150 metal-poor Galactic stars spanning $-$4.1 $<$ [Fe/H] $<$ $-$2.1. The targets were selected from the SkyMapper survey and include 90 objects with [Fe/H] $\le$ $-$3 of…

We present the high-resolution spectroscopic analysis of two new extremely metal-poor stars (EMPS) candidates in the dwarf spheroidal galaxy Sextans. These targets were pre-selected from medium resolution spectra centered around the Ca II…

Astrophysics of Galaxies · Physics 2021-01-04 R. Lucchesi , C. Lardo , F. Primas , P. Jablonka , P. North , G. Battaglia , E. Starkenburg , V. Hill , M. Irwin , P. Francois , M. Shetrone , E. Tolstoy , K. Venn

Very metal-poor (VMP) stars record the signatures of early accreted galaxies, making them essential tools for unraveling the early stages of Galaxy formation. Understanding the origin of VMP stars requires comprehensive studies of their…

Atmospheric parameters and oxygen abundances of 825 nearby FGK stars are derived using high-quality spectra and a non-LTE analysis of the 777 nm O I triplet lines. We assign a kinematic probability for the stars to be thin-disk (P1),…

Solar and Stellar Astrophysics · Physics 2015-06-12 I. Ramirez , C. Allende Prieto , D. L. Lambert

We aim to study the high-precision chemical abundances of metal-poor gas clouds at cosmic noon (2<z<4) and investigate the associated enrichment histories. We analyse the abundances of four newly discovered metal-poor gas clouds utilising…

Astrophysics of Galaxies · Physics 2024-11-20 Louise Welsh , Ryan Cooke , Michele Fumagalli , Max Pettini , Gwen C. Rudie

Based on high-resolution spectra obtained during gravitational microlensing events we present a detailed elemental abundance analysis of 32 dwarf and subgiant stars in the Galactic bulge. [ABRIDGED], we now have 58 microlensed bulge dwarfs…

In this paper we study the underlying stellar population of a sample of 65 nearby early-type galaxies predominantly located in low density environments. Ages, metallicities and [alpha/Fe] ratios have been derived through the comparison of…

Astrophysics · Physics 2010-10-28 F. Annibali , A. Bressan , R. Rampazzo , W. W. Zeilinger , L. Danese

We exploit the [Mg/Mn]-[Al/Fe] chemical abundance plane to help identify nearby halo stars in the 14th data release from the APOGEE survey that have been accreted on to the Milky Way. Applying a Gaussian Mixture Model, we find a `blob' of…

Astrophysics of Galaxies · Physics 2020-02-12 Payel Das , Keith Hawkins , Paula Jofre

Small stellar systems like dwarf galaxies are suggested to be the main building blocks of our Galaxy by numerical simulations in Lambda CDM models. The existence of star streams like Sagittarius tidal stream indicates that dwarf galaxies…

Solar and Stellar Astrophysics · Physics 2019-05-13 Qian-Fan Xing , Gang Zhao , Wako Aoki , Satoshi Honda , Hai-Ning Li , Miho N. Ishigaki , Tadafumi Matsuno

We study stellar population parameters of a sample of 13 dwarf galaxies located in poor groups of galaxies using high resolution spectra observed with VIMOS at the ESO-VLT. LICK-indices were compared with Simple Stellar Population models to…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-20 R. Grützbauch , F. Annibali , R. Rampazzo , A. Bressan , W. W. Zeilinger

We present a detailed chemical abundance and kinematic analysis of six extremely metal-poor ($-4.2 \leq$ [Fe/H] $\leq-$2.9) halo stars with very low neutron-capture abundances ([Sr/H] and [Ba/H]) based on high-resolution Magellan/MIKE…

We exploit the recent observations of extremely metal-poor (EMP) stars in the Galactic halo and investigate the constraints on the IMF of the stellar population that left these low-mass survivors of [Fe/H]<-2.5 and the chemical evolution…

Astrophysics of Galaxies · Physics 2011-02-11 Yutaka Komiya , Takuma Suda , Masayuki Y. Fujimoto

Context. The Galactic chemical evolution of sulphur is still under debate. At low metallicities some studies find no correlation between [S/Fe] and [Fe/H], others find [S/Fe] increasing towards lower metallicities, and still others find a…

Astrophysics of Galaxies · Physics 2013-12-18 E. Matrozis , N. Ryde , A. K. Dupree

The $r$-process enrichment in the Galaxy still remains elusive with regard to its nucleosynthesis conditions and the astrophysical sites where it occurs. As part of ongoing efforts to pinpoint the origin of chemically peculiar…

Solar and Stellar Astrophysics · Physics 2025-10-09 Pallavi Saraf , Thirupathi Sivarani , Carlos Allende Prieto , Shashikiran Ganesh , Drisya Karinkuzhi

Precise abundance ratios are determined for 94 dwarf stars with 5200 < Teff < 6300 K, -1.6 < [Fe/H] < -0.4, and distances D < 335 pc. Most of them have halo kinematics, but 16 thick-disk stars are included. Equivalent widths of atomic lines…

Astrophysics of Galaxies · Physics 2015-05-18 Poul E. Nissen , William J. Schuster

It is well-established that the vast majority of metal-poor Galactic halo stars shows evidence for enrichment by solely massive stars. Recent observations have identified more varied behavior in the pattern of elemental abundances measured…

Astrophysics · Physics 2016-08-30 Gerard Gilmore , Rosemary F. G. Wyse

We analyse the kinematic and chemical evolution of 203 distant spheroidal (elliptical and S0) galaxies at 0.2<z<0.8 which are located in different environments (rich clusters, low-mass clusters and in the field). VLT/FORS and CAHA/MOSCA…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-14 Alexander Fritz , Bodo L. Ziegler

We present the stellar population properties of 13 dwarf galaxies residing in poor groups (low-density environment, LDE) observed with VIMOS@VLT. Ages, metallicities, and [alpha/Fe] ratios were derived from the Lick indices Hbeta, Mgb,…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-20 F. Annibali , R. Grutzbauch , R. Rampazzo , A. Bressan , W. W. Zeilinger