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We present an abundance analysis based on high resolution spectra of 8 stars selected to span the full range in metallicity in the Draco dwarf spheroidal galaxy. We find [Fe/H] for the sample stars ranges from -1.5 to -3.0 dex. Combining…

Astrophysics of Galaxies · Physics 2009-08-05 Judith G. Cohen , Wenjin Huang

A pole-count analysis of the infrared 2MASS survey is presented, in order to identify faint stream-like structures within the halo of the Milky Way. Selecting stars with colours consistent with M-giant stars, we find a strong over-density…

Astrophysics · Physics 2016-08-30 R. A. Ibata , G. F. Lewis , M. J. Irwin , L. Cambresy

We constructed a sample of 13,798 stars with $T\rm_{eff}$, log $g$, [Fe/H], radial velocity, proper motions and parallaxes from LAMOST DR5 and Gaia DR2 in the LAMOST Complete Spectroscopic Survey of Pointing Area (LaCoSSPAr) at the Southern…

Astrophysics of Galaxies · Physics 2020-12-02 J. K. Zhao , X. H. Ye , H. Wu , M. Yang , Terry D. Oswalt , X. X. Xue , Y. Q. Chen , J. J. Zhang , G. Zhao

Extremely metal-poor stars are intrinsically rare, but emerging methods exist to accurately classify them from all-sky Gaia XP low-resolution spectra. To assess their overall accuracy for targeting metal-poor stars, we present a…

Solar and Stellar Astrophysics · Physics 2026-01-30 Riley Thai , Andrew R. Casey , Alexander Ji , Vedant Chandra , Hans-Walter Rix

We present evidence that multiple accretion events are required to explain the origin of the $Gaia$-Sausage and Enceladus (GSE) structures, based on an analysis of dynamical properties of main-sequence stars from the Sloan Digital Sky…

Astrophysics of Galaxies · Physics 2021-04-28 Young Kwang Kim , Young Sun Lee , Timothy C. Beers , Jae-Rim Koo

We identify stellar tidal debris from the $\omega$ Centauri ($\omega$ Cen) system among field stars in the APOGEE survey via chemical tagging using a neural network trained on APOGEE observations of the $\omega$ Cen core. We find a total of…

The outer halo regions of early-type galaxies carry key information about their past accretion history. However, spectroscopically probing the stellar component at such galactocentric radii is still challenging. Using Keck/DEIMOS, we have…

Large spectroscopic surveys plus Gaia astrometry have shown us that the inner stellar halo of the Galaxy is dominated by the debris of Gaia Enceladus/Sausage (GES). With the richness of data at hand, there are a myriad of ways these…

Astrophysics of Galaxies · Physics 2023-06-02 Andreia Carrillo , Alis J. Deason , Azadeh Fattahi , Thomas M. Callingham , Robert J. J. Grand

The second generation of stars in the GCs of the MW exhibit unusually high N, Na, or Al, compared to typical Galactic halo stars at similar metallicities. The halo field stars enhanced with such elements are believed to have originated in…

Astrophysics of Galaxies · Physics 2023-05-09 Changmin Kim , Young Sun Lee , Timothy C. Beers , Young Kwang Kim

We present kinematics of 35 highly r-process-enhanced ([Eu/Fe] >= +0.7) metal-poor (-3.8 < [Fe/H] < -1.4) field stars. We calculate six-dimensional positions and velocities, evaluate energies and integrals of motion, and compute orbits for…

Solar and Stellar Astrophysics · Physics 2018-10-17 Ian U. Roederer , Kohei Hattori , Monica Valluri

We present a multi-method investigation of four metal-poor G-type main-sequence stars to resolve their Galactic origins. By combining high-resolution spectroscopy from PolarBase, photometric/astrometric data from Gaia DR3, and spectral…

Solar and Stellar Astrophysics · Physics 2025-04-28 Deniz Cennet Çınar , Selçuk Bilir , Timur Şahin , Olcay Plevne

Context. Elemental abundances are of prime importance to help us reconstruct the origin and evolution of stars and galaxies in our Universe. Sulfur abundances have not been as heavily studied as other elements, so some details regarding its…

Solar and Stellar Astrophysics · Physics 2020-02-26 Ana Rita Costa Silva , Elisa Delgado Mena , Maria Tsantaki

We present abundances for seven stars in the (extremely) low-metallicity tail of the Sculptor dwarf spheroidal galaxy, from spectra taken with X-shooter on the ESO VLT. Targets were selected from the Ca II triplet (CaT) survey of the Dwarf…

Orbital characteristics based on Gaia Early Data Release 3 astrometric parameters are analyzed for ${\sim} 8,000$ metal-poor stars ([Fe/H] $\leq -0.8$) compiled from the RAdial Velocity Experiment (RAVE) Data Release 6. Selected as…

Astrophysics of Galaxies · Physics 2022-07-27 Derek Shank , Dante Komater , Timothy C. Beers , Vinicius M. Placco , Yang Huang

We identify six new CEMP stars ([C/Fe]>+0.7 and [Fe/H]< -1.8) and another seven likely candidates within the APOGEE database following Data Release 12. These stars have chemical compositions typical of metal-poor halo stars, e.g., mean…

Orbital characteristics based on Gaia Early Data Release 3 astrometric parameters are analyzed for ${\sim} 4000$ metal-poor stars ([Fe/H] $\leq -0.8$) compiled from the Best $\&$ Brightest survey. Selected as metal-poor candidates based on…

We performed a detailed study of the ratio of low-{\alpha} to high-{\alpha} stars in the Galactic halo as observed by the Gaia-ESO Survey. Using a sample of 381 metal-poor stars from the second internal data release, we found that the value…

By performing an orbital analysis within a Galactic model including a bar, we found that it is plausible that the newly discovered stars that show enhanced Al and N accompanied by Mg underabundances may have formed in the outer halo, or…

Astrophysics of Galaxies · Physics 2017-10-23 J. G. Fernández-Trincado , D. Geisler , E. Moreno , O. Zamora , A. C. Robin , S. Villanova

ED-2 is a stellar stream identified as a compact group in integrals of motion space in a local sample of halo stars from the third Gaia data release. Here we investigate its nature and possible association with known halo substructures. We…

Astrophysics of Galaxies · Physics 2023-10-18 E. Balbinot , A. Helmi , T. Callingham , T. Matsuno , E. Dodd , T. Ruiz-Lara

Two studies have recently reported the discovery of pronounced Halo substructure in the Sloan Digital Sky Survey (SDSS) commissioning data. Here we show that this Halo substructure is almost in its entirety due to the expected tidal stream…

Astrophysics · Physics 2009-05-29 Rodrigo Ibata , Michael Irwin , Geraint Lewis , Andrea Stolte