6 citations · 18 across the 22 of their papers we have counts for
23 papers
Star spots mimic the proposed abundance signatures of planet formation
Andrew R. Casey, Megan Bedell, Adam Wheeler +2
Trends with stellar elemental abundances and condensation temperature have been proposed as a possible tracer of rocky planet formation. Here we present an alternative explanation,…
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,…
A Probabilistic Framework for Population Studies of the Solar Neighborhood: Application to SDSS-V and Gaia
Ilija Medan, Keivan G. Stassun, Zachary Way +8
Studies of the Solar Neighborhood require spectroscopic follow-up of stars identified in astrometric surveys to fully characterize their physical properties. The SDSS-V Solar Neigh…
Searching for Stellar Activity Cycles using Flares II: The TESS CVZ
Tobin M. Wainer, Holland M. Stuart, Guadalupe Tovar Mendoza +3
Magnetic activity cycles provide a fundamental constraint on stellar dynamos, but remain difficult to identify beyond the Sun. However, recent studies have shown that flares offer…
Robust Heteroskedastic Matrix Factorization: A Generalization of PCA that Flags Outliers and Handles Missing Data
Thomas Hilder, David W. Hogg, Andrew R. Casey +1
We present Robust Heteroskedastic Matrix Factorization (RHMF), a generalization of Principal Component Analysis (PCA) that is robust to outliers, handles per-feature uncertainties…
BOSS-CLAM: Utilizing a Constrained Linear Absorption Model to Infer Stellar Parameters from BOSS Spectra
Ilija Medan, Andrew R. Casey, Alexander P. Ji +13
Large spectroscopic surveys require robust pipelines capable of inferring stellar parameters over a wide range of the Hertzsprung-Russell (HR) diagram from data of varying quality.…
A constrained linear model for continuum normalization of stellar spectra
Andrew R. Casey, Adam Wheeler, Megan Bedell +3
Inferring stellar parameters and chemical abundances by forward modeling stellar spectra usually requires a spectral synthesis code, or an emulator constructed from a curated train…
Perhaps there is no brown dwarf desert? A study of sub-stellar companions with Gaia DR3
A. L. Wallace, A. R. Casey
The brown dwarf desert describes a range of orbital periods (<5 years) in which fewer brown dwarf-mass companions have been observed around Sun-like stars, when compared to planets…
Optimal and Unbiased Fluxes from Up-the-Ramp Detectors under Variable Illumination
Bowen Li, Kevin A. McKinnon, Andrew K. Saydjari +6
Near-infrared (NIR) detectors -- which use non-destructive readouts to measure time-series counts-per-pixel -- play a crucial role in modern astrophysics. Standard NIR flux extract…
The Astrometric Resoeccentric Degeneracy: Eccentric Single Planets Mimic 2:1 Resonant Planet Pairs in Astrometry
Daniel A. Yahalomi, Tiger Lu, Philip J. Armitage +4
Detections of long-period giant exoplanets will expand dramatically with Gaia Data Release 4 (DR4), but interpreting these signals will require care. We derive the astrometric reso…
Stellar Parameters of BOSS M dwarfs in SDSS-V DR19
Dan Qiu, Jennifer A. Johnson, Chao Liu +15
We utilized the Stellar LAbel Machine (SLAM), a data-driven model based on Support Vector Regression, to derive stellar parameters ([Fe/H], , and ) for SDSS-V…
Looking for Companionship: Radial Velocity Follow-Up of Lithium-Rich Giants with ESPRESSO
Maryum Sayeed, Andrew R. Casey, Benjamin T. Montet +4
Lithium-rich red giants have been a long-standing mystery in stellar astrophysics. A leading theory to explain these chemically peculiar and rare objects is interactions with a clo…
Unified Spectrospatial Forward Models: Spatially Continuous Maps of Weak Emission Lines in the Rosette Nebula with SDSS-V LVM
Thomas Hilder, Andrew R. Casey, Julianne J. Dalcanton +14
Analyses of IFU data are typically performed on a per-spaxel basis, with each spectrum modelled independently. For low signal-to-noise (S/N) features such as weak emission lines, e…
The Importance of Standardizing Spectra in the Era of Large Spectroscopic Surveys: A Case Study of M Dwarfs in SDSS-V
Ilija Medan, Zachary Way, Bárbara Rojas-Ayala +8
SDSS-V will obtain 100,000s of medium-resolution, optical spectra of M dwarfs with the BOSS instrument. M dwarfs have complex atmospheres, and their spectra contain many wide and d…
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…
Optical Spectroscopy Reveals Hidden Neutron-capture Elemental Abundance Differences among APOGEE-identified Chemical Doppelgängers
Catherine Manea, Melissa Ness, Keith Hawkins +9
Grouping stars by chemical similarity has the potential to reveal the Milky Way's evolutionary history. The APOGEE stellar spectroscopic survey has the resolution and sensitivity f…
Mapping the Distant and Metal-Poor Milky Way with SDSS-V
Vedant Chandra, Phillip A. Cargile, Alexander P. Ji +28
The fifth-generation Sloan Digital Sky Survey (SDSS-V) is conducting the first all-sky low-resolution spectroscopic survey of the Milky Way's stellar halo. We describe the stellar…
Sloan Digital Sky Survey-V: Pioneering Panoptic Spectroscopy
Juna A. Kollmeier, Hans-Walter Rix, Conny Aerts +217
The Sloan Digital Sky Survey-V (SDSS-V) is pioneering panoptic spectroscopy: it is the first all-sky, multi-epoch, optical-to-infrared spectroscopic survey. SDSS-V is mapping the s…
SDSS-V Milky Way Mapper (MWM): ASPCAP Stellar Parameters and Abundances in SDSS-V Data Release 19
Szabolcs Mészáros, Paula Jofré, Jennifer A. Johnson +25
The goal of this paper is to describe the science verification of Milky Way Mapper (MWM) APOGEE Stellar Parameter and Chemical Abundances Pipeline (ASPCAP) data products published…
Probing Binary Architectures of Lithium-Rich Giants in GALAH with COSMIC and Stellar Models
Maryum Sayeed, Selina Yang, Giulia Cinquegrana +5
Surface lithium is depleted when a star goes through the first dredge-up phase, yet of red giants are found to be Li-rich. The formation mechanism for these remains uncertain…
: A generative, multi-output, latent-variable model for astronomical data with noisy labels
Danny Horta, Adrian M. Price-Whelan, David W. Hogg +2
The large volume of spectroscopic data available now and from near-future surveys will enable high-dimensional measurements of stellar parameters and properties. Current methods fo…
A Data-Driven M Dwarf Model and Detailed Abundances for 17,000 M Dwarfs in SDSS-V
Aida Behmard, Melissa K. Ness, Andrew R. Casey +6
The cool temperatures of M dwarf atmospheres enable complex molecular chemistry, making robust characterization of M dwarf compositions a long-standing challenge. Recent modificati…
Nova contributions to the chemical evolution of the Milky Way
Alex J. Kemp, Amanda I. Karakas, Andrew R. Casey +3
Context. The explosive burning that drives nova eruptions results in unique nucleosynthesis that heavily over-produces certain isotopes relative to the solar abundance. However, no…