342 citations · 6.5k across the 144 of their papers we have counts for
78 papers · 1 filter
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…
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: 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 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…
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…
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 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…
Elemental abundances of 44 very metal-poor stars determined from Subaru/IRD near-infrared spectra
Wako Aoki, Timothy C. Beers, Satoshi Honda +12
Abundances of five elements, Na, Mg, Al, Si, and Sr, are investigated for 44 very metal-poor stars (-4.0 < [Fe/H] < -1.5) in the Galactic halo system based on an Local Thermodinami…
Abundances of iron-peak elements in 58 bulge spheroid stars from APOGEE
B. Barbuy, A. C. S. Friaça, H. Ernandes +22
Stars presently identified in the bulge spheroid are probably very old, and their abundances can be interpreted as due to the fast chemical enrichment of the early Galactic bulge.…
The R-Process Alliance: Fifth Data Release from the Search for R-Process-Enhanced Metal-poor Stars in the Galactic Halo with the GTC
Avrajit Bandyopadhyay, Rana Ezzeddine, Carlos Allende Prieto +9
Understanding the abundance pattern of metal-poor stars and the production of heavy elements through various nucleosynthesis processes offers crucial insights into the chemical evo…
The S-PLUS Ultra-Short Survey: first data release
Hélio D. Perottoni, Vinicius M. Placco, Felipe Almeida-Fernandes +15
This paper presents the first public data release of the S-PLUS Ultra-Short Survey (USS), a photometric survey with short exposure times, covering approximately 9300 deg of t…
The R-Process Alliance: 2MASS J22132050-5137385, the Star with the Highest-known r-process Enhancement at [Eu/Fe] = +2.45
Ian U. Roederer, Timothy C. Beers, Kohei Hattori +6
We present stellar parameters and chemical abundances of 47 elements detected in the bright (V = 11.63) very metal-poor ([Fe/H] = -2.20 +- 0.12) star 2MASS J22132050-5137385. We ob…
The R-Process Alliance: Analysis of Limited-r Stars
T. Xylakis-Dornbusch, T. T. Hansen, T. C. Beers +8
Context. In recent years, the R-Process Alliance (RPA) has conducted a successful search for stars enhanced in elements produced by the rapid neutron-capture (r-)process. In partic…
The -Process Alliance: Detailed Composition of an -Process Enhanced Star with UV and Optical Spectroscopy
Shivani P. Shah, Rana Ezzeddine, Ian U. Roederer +8
We present a detailed chemical-abundance analysis of a highly -process enhanced (RPE) star, 2MASS J00512646-1053170, using high-resolution spectroscopic observations with $Hubbl…
Element abundance patterns in stars indicate fission of nuclei heavier than uranium
Ian U. Roederer, Nicole Vassh, Erika M. Holmbeck +9
The heaviest chemical elements are naturally produced by the rapid neutron-capture process (r-process) during neutron star mergers or supernovae. The r-process production of elemen…
rrlfe: Software for Generating and Applying Metallicity Calibrations for RR Lyrae Variable Stars Across a Wide Range of Phases and Temperatures
Eckhart Spalding, Ronald Wilhelm, Nathan De Lee +7
RR Lyrae stars play a central role in tracing phase-space structures within the Milky Way because they are easy to identify, are relatively luminous, and are found in large numbers…
SPLUS J142445.34-254247.1: An R-Process Enhanced, Actinide-Boost, Extremely Metal-Poor star observed with GHOST
Vinicius M. Placco, Felipe Almeida-Fernandes, Erika M. Holmbeck +33
We report on the chemo-dynamical analysis of SPLUS J142445.34-254247.1, an extremely metal-poor halo star enhanced in elements formed by the rapid neutron-capture process. This sta…
Chemodynamical Properties and Ages of Metal-Poor Stars in S-PLUS
Felipe Almeida-Fernandes, Vinicius Placco, Helio Rocha-Pinto +10
Metal-poor stars are key to our understanding of the early stages of chemical evolution in the Universe. New multi-filter surveys, such as the Southern Photometric Local Universe S…
The miniJPAS survey: stellar atmospheric parameters from 56 optical filters
H. -B. Yuan, L. Yang, P. Cruz +29
With a unique set of 54 overlapping narrow-band and two broader filters covering the entire optical range, the incoming Javalambre-Physics of the Accelerating Universe Astrophysica…
The R-Process Alliance: Abundance Universality among Some Elements at and between the First and Second R-Process Peaks
Ian U. Roederer, John J. Cowan, Marco Pignatari +11
We present new observational benchmarks of rapid neutron-capture process (r-process) nucleosynthesis for elements at and between the first (A ~ 80) and second (A ~ 130) peaks. Our…
Abundance analysis of APOGEE spectra for 58 metal-poor stars from the bulge spheroid
R. Razera, B. Barbuy, T. C. Moura +19
The central part of the Galaxy host a multitude of stellar populations, including the spheroidal bulge stars, stars moved to the bulge through secular evolution of the bar, inner h…