22 citations · 58 across the 21 of their papers we have counts for
25 papers
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…
Payne4GAIN: NLTE Corrections for Red Giants in Milky Way Mapper using H-Band Neural Network Emulators
Pierre Thibodeaux, Alexander P. Ji, Nicholas Storm +12
The majority of spectroscopic surveys assume local thermodynamic equilibrium (LTE) during the modeling of stellar spectra. This assumption begins to break down for luminous stars,…
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…
Evaluating Classifications of Extremely Metal-poor Candidates Selected from Gaia XP Spectra
Riley Thai, Andrew R. Casey, Alexander Ji +2
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 accur…
Discovery of the First Five Carbon-Enhanced Metal-Poor Stars in the LMC
Madeline Lucey, Vedant Chandra, Alexander Ji +7
A substantial fraction of metal-poor stars in the local Milky Way halo exhibit large overabundances of carbon. These stars, dubbed Carbon-Enhanced Metal-Poor (CEMP) stars, provide…
A nearly pristine star from the Large Magellanic Cloud
Alexander P. Ji, Vedant Chandra, Selenna Mejias-Torres +28
The first stars formed out of pristine gas, causing them to be so massive that none are expected to have survived until today. If their direct descendants were sufficiently low-mas…
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…
A Bimodal Metallicity Distribution Function in the Ultra-Faint Dwarf Galaxy Reticulum II
Alice M. Luna, Alexander P. Ji, Anirudh Chiti +6
Star formation in ultra-faint dwarf galaxies (UFDs, ) is suppressed by reionization, but may not be completely quenched. The metallicity distribution function (MD…
Chemical Abundances in the Metal-Poor Globular Cluster ESO 280-SC06: A Formerly Massive, Tidally Disrupted Globular Cluster
Sam A. Usman, Alexander P. Ji, Jandrie Rodriguez +6
We present the first high-resolution abundance study of ESO 280-SC06, one of the least luminous and most metal-poor gravitationally bound Milky Way globular clusters. Using Magella…
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…
Eridanus III and DELVE 1: Carbon-rich Primordial Star Clusters or the Smallest Dwarf Galaxies?
Joshua D. Simon, Ting S. Li, Alexander P. Ji +8
We present spectroscopy of the ultra-faint Milky Way satellites Eridanus III (Eri III) and DELVE 1. We identify eight member stars in each satellite and place non-constraining uppe…
All the Little Things in Abell 2744: 1000 Gravitationally Lensed Dwarf Galaxies at from JWST NIRCam Grism Spectroscopy
Rohan P. Naidu, Jorryt Matthee, Ivan Kramarenko +31
Dwarf galaxies hold the key to crucial frontiers of astrophysics, however, their faintness renders spectroscopy challenging. Here we present the JWST Cycle 2 survey, All the Little…
Chemical Abundances in the Leiptr Stellar Stream: A Disrupted Ultra-faint Dwarf Galaxy?
Kaia R. Atzberger, Sam A. Usman, Alexander P. Ji +11
Chemical abundances of stellar streams can be used to determine the nature of a stream's progenitor. Here we study the progenitor of the recently discovered Leiptr stellar stream,…
ACACIAS I: Element abundance labels for 192 stars in the dwarf galaxy NGC 6822
Melissa K. Ness, J. Trevor Mendel, Sven Buder +8
The element abundances of local group galaxies connect enrichment mechanisms to galactic properties and serve to contextualise the Milky Way's abundance distributions. Individual s…
The Rise of the -Process in the Gaia-Sausage/Enceladus Dwarf Galaxy
Xiaowei Ou, Alexander P. Ji, Anna Frebel +2
Neutron star mergers (NSMs) produce copious amounts of heavy r-process elements after a time delayed inspiral process. Once NSMs are present in a galaxy, r-process elements, such a…
LAMOST J1010+2358 is not a Pair-Instability Supernova Relic
Pierre N. Thibodeaux, Alexander P. Ji, William Cerny +2
The discovery of a star formed out of pair-instability supernova ejecta would have massive implications for the Population III star initial mass function and the existence of stars…
Chemical Diversity on Small Scales -- Abundance Analysis of the Tucana V Ultra-Faint Dwarf Galaxy
Terese T. Hansen, Joshua D. Simon, Ting S. Li +5
The growing number of Milky Way satellites detected in recent years has introduced a new focus for stellar abundance analysis. Abundances of stars in satellites have been used to p…
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…
Spectacular nucleosynthesis from early massive stars
Alexander P. Ji, Sanjana Curtis, Nicholas Storm +39
Stars formed with initial mass over 50 Msun are very rare today, but they are thought to be more common in the early universe. The fates of those early, metal-poor, massive stars a…
Enrichment by Extragalactic First Stars in the Large Magellanic Cloud
Anirudh Chiti, Mohammad Mardini, Guilherme Limberg +8
The Large Magellanic Cloud (LMC) is the Milky Way's most massive satellite galaxy, which only recently (~2 billion years ago) fell into our Galaxy. Since stellar atmospheres preser…
Multiple Populations and a CH Star Found in the 300S Globular Cluster Stellar Stream
Sam A. Usman, Alexander P. Ji, Ting S. Li +14
Milky Way globular clusters (GCs) display chemical enrichment in a phenomenon called multiple stellar populations (MSPs). While the enrichment mechanism is not fully understood, th…