342 citations · 6.5k across the 144 of their papers we have counts for
150 papers
AI and The Enclosure of the Scientific Commons
P. K. G. Williams
The scientific literature can be viewed as an "information commons:" an intangible resource that "no one owns and is shared by everyone." There are well-established economic and po…
The -Process Alliance: On J00101735, an Accreted, Chemically Unusual, Metal-poor Star with -process Enhancement
Zoe Hackshaw, Rana Ezzeddine, Shivani P. Shah +11
We present a detailed chemo-dynamical analysis of the chemically peculiar very metal-poor ([Fe/H]) Milky Way (MW) halo star, 2MASS J001017581735387 (hereafter J0…
Chemo-dynamical Analysis of a CNO-Enhanced Ultra Metal-poor Star (): Insights into Early Enrichment by Faint Population III Supernova
Guilherme Limberg, Vinicius M. Placco, Alexander P. Ji +10
We report an independent identification of the ultra metal-poor (UMP) star () DR3 $\texttt{source_id}$ 4795913112968206720 (GDR3_479591) in the miss…
The S-PLUS Fifth Data-Release: Over 4500 square degrees of the Southern Sky and a multicolor view of the Hydra and Antlia galaxy clusters
Erik Vinicius Rodrigues de Lima, Gustavo Bernhard Oliveira Schwarz, Fábio Rafael Herpich +55
We present the 5th data release (DR5) of the Southern Photometric Local Universe Survey (S-PLUS), covering 4592 square degrees across 2491 fields. Observations were conducted with…
Near-Infrared Observations of BD+44 493 with IGRINS-2
Vinicius M. Placco, William D. Vacca
We present high-resolution (R~45,000), high signal-to-noise (S/N>200) H and K-band spectra of BD+44 493, obtained with the newly commissioned IGRINS-2 instrument on the Gemini Nort…
The Carbon-Dependent Binary Frequency of CEMP-no Stars
John D. Dixon, Terese T. Hansen, Jennifer Marshall +15
Studies of the oldest and most metal-poor stars in the Milky Way confirm a common chemical signature of high carbon abundances and subsolar neutron-capture enrichment. The so-calle…
The \emph{R}-process Alliance: A Bright, Strongly \emph{R}-process-enhanced Extremely Metal-poor Star Observed with GHOST
Mohammad K. Mardini, Anna Frebel, Vinicius M. Placco +8
We present a detailed chemical-abundance and kinematic analysis of four extremely metal-poor (EMP; [Fe/H] ) stars identified from \textit{Gaia} BP/RP data in our ongoing…
The -Process Alliance: The -Process Enhancement of Stars from Chemodynamically Tagged Groups in the Milky Way Halo
Jessica Merritt Agnos, Charli M. Sakari, Pedro Silva +9
As part of the ongoing work of the -Process Alliance (RPA), detailed abundance measurements of 29 heavy elements in three metal-poor stars, 2MASS J145929813852558, 2MASS J194…
The Metallicity Gradient of Sagittarius Dwarf Spheroidal Galaxy Prior to Infall Constrained by S-PLUS Observations of its Tidal Stream
Felipe Almeida-Fernandes, Guilherme Limberg, Hélio D. Perottoni +16
We study the metallicity distribution along the Sagittarius (Sgr) stream using photometric metallicities from S-PLUS DR4, combined with Gaia DR3 kinematics and APOGEE DR17 spectros…
The -Process Alliance: Actinide Abundances, Variation, and Evolution in Metal-Poor Stars
Shivani P. Shah, Rana Ezzeddine, Erika M. Holmbeck +11
The actinides, including thorium (Th), are the heaviest observable elements synthesized in the universe, holding clues to the extremes of the astrophysical and nuclear conditions o…
The Actinide-Boost Star LAMOST J122216.85-063345.2: A Detailed R-process Abundance Study with Gemini-S/GHOST
Miji Jeong, Young Sun Lee, Vinicius M. Placco +15
We present a detailed chemical-abundance analysis of an actinide-boost ((Th/Dy) = -0.74) star, LAMOST J122216.85-063345.2 (J1222), a very metal-poor ([Fe/H] = -2.45) halo st…
Carbon-Enhanced Metal-Poor Star Candidates in the Milky Way from J-PLUS and S-PLUS
Jihye Hong, Timothy C. Beers, Yang Huang +4
Recent large-scale multi-band photometric surveys now enable elemental-abundance estimates for millions of stars with accuracies approaching those of low- to medium-resolution spec…
HE0144-4657: A Carbon-Enhanced Ultra Metal-Poor Star ([Fe/H] ~ -4.1) from the Helmi Stream Disrupted Dwarf Galaxy
Vinicius M. Placco, Guilherme Limberg, Catherine R. Kennedy +1
We present the discovery of HE0144-4657, an ultra metal-poor, CNO-enhanced star dynamically associated with the Helmi Stream disrupted dwarf-galaxy remnant. This star was first ide…
The R-Process Alliance: Exploring the cosmic scatter among ten r-process sites with stellar abundances
Mila Racca, Terese T. Hansen, Ian U. Roederer +11
The astrophysical origin of the rapid neutron-capture process (r-process), which produces about half of the elements heavier than iron, remains uncertain. The oldest, most metal-po…
Abundances of Rarely Detected s-process Elements Derived from the Ultraviolet Spectrum of the s-process-enhanced Metal-poor Star HD 196944
Ian U. Roederer, Vinicius M. Placco, Amanda I. Karakas +2
We present an analysis of the heavy-element abundances of HD 196944, a carbon-enhanced metal-poor (CEMP) star enriched with elements produced by the slow neutron-capture process (s…
Not-so-heavy metal(s): Chemical Abundances in the Ultra-faint Dwarf Galaxies Eridanus IV and Centaurus I
Mairéad E Heiger, Alexander P Ji, Ting S Li +18
We present detailed chemical abundances of the brightest star in each of the ultra-faint dwarf galaxies Eridanus IV and Centaurus I using high-resolution Magellan/MIKE spectroscopy…
A second-generation star in a relic dwarf galaxy
Anirudh Chiti, Vinicius M. Placco, Andrew B. Pace +22
Stars that contain only trace amounts of elements heavier than helium, referred to as having low "metallicity", preserve the chemical fingerprints of the first generation of stars…
Discovery of an Star in XP Spectra
Guilherme Limberg, Vinicius M. Placco, Alexander P. Ji +5
We report on the discovery of GDR3_526285 ( DR3 Source ID 5262850721755411072), a star with and one of the lowest metal ($\text{atomic number} >…
Abundances of P, S, and K in 58 bulge spheroid stars from APOGEE
B. Barbuy, H. Ernandes, A. C. S. Friaça +25
We have previously studied several elements in 58 selected bulge spheroid stars, based on spectral lines in the H-band. We now derive the abundances of the less-studied elements ph…
The DECam MAGIC Survey: Spectroscopic Follow-up of the Most Metal-Poor Stars in the Distant Milky Way Halo
Vinicius M. Placco, Guilherme Limberg, Anirudh Chiti +21
In this work, we present high-resolution spectroscopic observations for six metal-poor stars with [Fe/H]<-3 (including one with [Fe/H]<-4), selected using narrow-band Ca II HK phot…
Spectroscopic Analysis of Pictor II: a very low metallicity ultra-faint dwarf galaxy bound to the Large Magellanic Cloud
A. B. Pace, T. S. Li, A. P. Ji +30
We present Magellan/IMACS and Magellan/MIKE spectroscopy of the ultra-faint dwarf (UFD) galaxy Pictor~II (Pic~II) that is located only 12 kpc from the Large Magellanic Cloud (LMC).…
Probing Abundance Variations among Multiple Stellar Populations in the Metal-Poor Globular Cluster NGC 2298 using Gemini-South/GHOST
Avrajit Bandyopadhyay, Rana Ezzeddine, Vinicius M. Placco +3
Studying the abundances in metal-poor globular clusters is crucial for understanding the formation of the Galaxy and the nucleosynthesis processes in the early Universe. We observe…
The DECam MAGIC Survey: A Wide-field Photometric Metallicity Study of the Sculptor Dwarf Spheroidal Galaxy
Fabrícia O. Barbosa, Anirudh Chiti, Guilherme Limberg +26
The metallicity distribution function and internal chemical variations of a galaxy are fundamental to understand its formation and assembly history. In this work, we analyze photom…
The R-Process Alliance: Hunting for gold in the near-UV spectrum of 2MASS J05383296-5904280
Terese T. Hansen, Ian U. Roederer, Shivani P. Shah +10
Context. Over the past few years, the -Process Alliance (RPA) has successfully carried out a search for stars that are highly enhanced in elements produced via the rapid neutron…