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Related papers: The GALAH Survey: A New Sample of Extremely Metal-…

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Metal-poor stars provide the fossil record of Galactic chemical evolution and the nucleosynthesis processes that took place at the earliest times in the history of our Galaxy. From detailed abundance studies of low mass, extremely…

Solar and Stellar Astrophysics · Physics 2015-03-11 T. Hansen , C. J. Hansen , N. Christlieb , D. Yong , T. C. Beers , J. Andersen

With the dual aims of enlarging the list of extremely metal-poor stars identified in the Galaxy, and boosting the numbers of moderately metal-deficient stars in directions that sample the rotational properties of the thick disk, we have…

Context. The study of the oldest and most metal-poor stars in our Galaxy promotes our understanding of the Galactic chemical evolution and the beginning of Galaxy and star formation. However, they are notoriously difficult to find, with…

Astrophysics of Galaxies · Physics 2022-08-04 Theodora Xylakis-Dornbusch , Norbert Christlieb , Karin Lind , Thomas Nordlander

Identifying and characterizing young stars in the Solar neighbourhood is essential to find and describe planets in the early stages of their evolution. This work seeks to identify nearby young stars showing a Lithium 6707.78$\,\AA$…

Solar and Stellar Astrophysics · Physics 2019-02-20 M. Žerjal , M. J. Ireland , T. Nordlander , J. Lin , L. Casagrande , J. Horner , G. De Silva , S. Martell , K. Čotar , G. Traven , T. Zwitter

We have undertaken a spectroscopic survey of field stars to find metal-poor objects among them. Observations are carried out using OMR spectrograph attached to 2.3m telescope at VBO Kavalur, India. The sample of candidate stars are chosen…

Astrophysics · Physics 2007-05-23 Sunetra Giridhar , Aruna Goswami

We obtain estimates of stellar atmospheric parameters for a previously published sample of 1777 relatively bright (9 < B < 14) metal-poor candidates from the Hamburg/ESO Survey. The original Frebel et al. analysis of these stars was only…

We explore the kinematics and orbital properties of a sample of 323 very metal-poor stars in the halo system of the Milky Way, selected from the high-resolution spectroscopic follow-up studies of Aoki et al. and Yong et al. The combined…

Astrophysics of Galaxies · Physics 2015-06-18 Daniela Carollo , Ken Freeman , Timothy Beers , Vinicius Placco , Jason Tumlinson , Sarah Martell

Metal-poor stars are important tools for tracing the early history of the Milky Way, and for learning about the first generations of stars. Simulations suggest that the oldest metal-poor stars are to be found in the inner Galaxy. Typical…

As a typical data-driven method, deep learning becomes a natural choice for analysing astronomical data nowadays. In this study, we built a deep convolutional neural network to estimate basic stellar parameters $T\rm{_{eff}}$, log g,…

Astrophysics of Galaxies · Physics 2022-08-03 Zhuohan Li , Gang Zhao , Yuqin Chen , Xilong Liang , Jingkun Zhao

We estimate ([M/H], [$\alpha$/M]) for 48 million giants and dwarfs in low-dust extinction regions from the Gaia DR3 XP spectra by using tree-based machine-learning models trained on APOGEE DR17 and metal-poor star sample \revise{from} Li et…

Astrophysics of Galaxies · Physics 2025-02-27 Kohei Hattori

We investigate the properties of 1262 red giant stars with high photospheric abundances of lithium observed by the GALAH and \Ktwo-HERMES surveys, and discuss them in the context of proposed mechanisms for lithium enrichment and…

The GALAH survey targets one million stars in the southern hemisphere down to a limiting magnitude of V = 14 at the Anglo- Australian Telescope. The project aims to measure up to 30 elemental abundances and radial velocities (~1 km/s…

Astrophysics of Galaxies · Physics 2015-09-16 J. Bland-Hawthorn , S. Sharma , K. Freeman

We present a homogeneous chemical abundance analysis of 16 elements in 190 metal-poor Galactic halo stars (38 program and 152 literature objects). The sample includes 171 stars with [Fe/H] < -2.5, of which 86 are extremely metal poor,…

We present results from an observing campaign to identify low-metallicity stars in the Best & Brightest Survey. From medium-resolution (R ~ 1, 200 - 2, 000) spectroscopy of 857 candidates, we estimate the stellar atmospheric parameters…

In this work, we study the chemical compositions and kinematic properties of six metal-poor stars with [Fe/H] $< -2.5$ in the Galactic halo. From high-resolution (R $\sim$~110,000) spectroscopic observations obtained with the Lick/APF, we…

Astrophysics of Galaxies · Physics 2019-09-04 Mohammad K. Mardini , Vinicius M. Placco , Ali Taani , Haining Li , Gang Zhao

We analyse the location of extremely metal-poor stars (EMPs, [Fe/H]$ < -3$) in 198 Milky Way (MW)/M31-like galaxies at $z=0$ in the TNG50 simulation. Each system is divided into four kinematically-defined morphological stellar components…

Astrophysics of Galaxies · Physics 2022-12-14 Li-Hsin Chen , Annalisa Pillepich , Simon C. O. Glover , Ralf S. Klessen

We present a high-resolution elemental-abundance analysis for a sample of 23 very metal-poor (VMP; [Fe/H] < -2.0) stars, 12 of which are extremely metal-poor (EMP; [Fe/H] < -3.0), and 4 of which are ultra metal-poor (UMP; [Fe/H] < -4.0).…

Solar and Stellar Astrophysics · Physics 2015-07-15 T. Hansen , C. J. Hansen , N. Christlieb , T. C. Beers , D. Yong , M. S. Bessell , A. Frebel , A. E. Garcia Perez , V. M. Placco , J. E. Norris , M. Asplund

Carbon-enhanced metal-poor (CEMP) stars span a wide range of stellar populations, from bona fide second-generation stars to later forming stars that provide excellent probes of, e.g., binary mass transfer. Here we analyse 11 metal-poor…

We report the discovery of 34 stars in the Hamburg/ESO Survey for metal-poor stars and the Sloan Digital Sky Survey that have [Fe/H] < -3.0. Their median and minimum abundances are [Fe/H] = -3.1 and -4.1, respectively, while 10 stars have…