Publications (40)
Milky Way Mapper decoded abundances -- II: From patterns to paths
Melissa K. Ness, Sarah Aquilina, Jennifer Mead +15
The element abundances of Milky Way disc stars encode entangled imprints of multiple enrichment processes, making it difficult to uncover the underlying chemical evolution. Here we…
mmCounter: Static People Counting in Dense Indoor Scenarios Using mmWave Radar
Tarik Reza Toha, Shao-Jung, Lu +1
mmWave radars struggle to detect or count individuals in dense, static (non-moving) groups due to limitations in spatial resolution and reliance on movement for detection. We prese…
Revealing the Chemical Structure of the Magellanic Clouds with APOGEE. II. Abundance Gradients of the Large Magellanic Cloud
Joshua T. Povick, David L. Nidever, Steven R. Majewski +10
We present the abundance gradients of the Large Magellanic Cloud (LMC) for 25 elemental abundance ratios and their respective temporal evolution as well as age-[X/Fe] trends using…
Milky Way Mapper decoded abundances -- I. Shared disc enrichment patterns
Melissa K. Ness, Sarah Aquilina, Jennifer Mead +15
Elemental abundances in the Milky Way disc trace its star-formation and enrichment history, but predicting these abundances from theory is limited by uncertain nucleosynthetic yiel…
When is it permissible for artificial intelligence to lie? A trust-based approach
Tae Wan Kim, Tong, Lu +4
Conversational Artificial Intelligence (AI) used in industry settings can be trained to closely mimic human behaviors, including lying and deception. However, lying is often a nece…
The Milky Way Radial Metallicity Gradient as an Equilibrium Phenomenon: Why Old Stars are Metal-Rich
James W. Johnson, David H. Weinberg, Guillermo A. Blanc +12
Metallicities of both gas and stars decline toward large radii in spiral galaxies, a trend known as the radial metallicity gradient. We quantify the evolution of the metallicity gr…
Evolution of the Exoplanet Size Distribution: Forming Large Super-Earths Over Billions of Years
Trevor J. David, Gabriella Contardo, Angeli Sandoval +9
The radius valley, a bifurcation in the size distribution of small, close-in exoplanets, is hypothesized to be a signature of planetary atmospheric loss. Such an evolutionary pheno…
mmAnomaly: Leveraging Visual Context for Robust Anomaly Detection in the Non-Visual World with mmWave Radar
Tarik Reza Toha, Shao-Jung, Lu +2
mmWave radar enables human sensing in non-visual scenarios-e.g., through clothing or certain types of walls-where traditional cameras fail due to occlusion or privacy limitations.…
On Convective Turnover Times and Dynamos In Low-Mass Stars
Seth Gossage, Rocio Kiman, Kristina Monsch +7
The relationship between magnetic activity and Rossby number is one way through which stellar dynamos can be understood. Using measured rotation rates and X-ray to bolometric lumin…
Universal properties of the high- and low-α disk: small intrinsic abundance scatter and migrating stars
Yuxi, Lu, Melissa Ness +2
The detailed age-chemical abundance relations of stars measures time-dependent chemical evolution.These trends offer strong empirical constraints on nucleosynthetic processes, as w…
Astraea: Predicting Long Rotation Periods with 27-Day Light Curves
Yuxi, Lu, Ruth Angus +5
The rotation periods of planet-hosting stars can be used for modeling and mitigating the impact of magnetic activity in radial velocity measurements and can help constrain the high…
Measuring Long Stellar Rotation Periods (>10 days) from TESS FFI Light Curves is Possible: An Investigation Using TESS and ZTF
Soichiro Hattori, Ruth Angus, Daniel Foreman-Mackey +3
The rotation period of a star is an important quantity that provides insight into its structure and state. For stars with surface features like starspots, their periods can be infe…
Insights into the Exoplanet Radius Valley from Host-Star Ages, Activity, Chemistry, and Birth Radius
Xunzhou Chen, Tiancheng Sun, Yuxi +3
The radius valley, a bimodal feature in the size distribution of close-in small exoplanets, is widely interpreted as a signature of atmospheric loss and therefore provides a key co…
ChronoFlow: A Data-Driven Model for Gyrochronology
Phil R. Van-Lane, Joshua S. Speagle, Gwendolyn M. Eadie +6
Gyrochronology is a technique for constraining stellar ages using rotation periods, which change over a star's main sequence lifetime due to magnetic braking. This technique shows…
Gyro-Kinematic Ages for around 30,000 Kepler Stars
Yuxi, Lu, Ruth Angus +3
Estimating stellar ages is important for advancing our understanding of stellar and exoplanet evolution and investigating the history of the Milky Way. However, ages for low-mass s…
Stellar Mergers or Truly Young? Intermediate-Age Stars on Highly-Radial Orbits in the Milky Way's Stellar Halo
Danny Horta, Yuxi, Lu +3
Reconstructing the mass assembly history of the Milky Way relies on obtaining detailed measurements of the properties of many stars in the Galaxy, especially in the stellar halo. O…
Charge Migration and Residual Non-Linearity in NIRSpec BOTS Observations
Munazza K. Alam, Leonardo Ubeda, Qinyan +3
We investigate the effect of charge migration and residual non-linearity on the JWST/NIRSpec G395H NRS1 and NRS2 detectors using Bright Object Time Series (BOTS) observations of th…
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…
An error event sensitive trade-off between rate and coding gain in MIMO MAC
Toni Ernvall, Jyrki Lahtonen, Hsiao-feng +2
This work considers space-time block coding for the Rayleigh fading multiple-input multiple-output (MIMO) multiple access channel (MAC). If we suppose that the receiver is performi…
Remarks on the Criteria of Constructing MIMO-MAC DMT Optimal Codes
Hsiao-feng, Lu, Jyrki Lahtonen +2
In this paper we investigate the criteria proposed by Coronel et al. for constructing MIMO MAC-DMT optimal codes over several classes of fading channels. We first give a counterexa…
The impact of early massive mergers on the chemical evolution of Milky Way-like galaxies: insights from NIHAO-UHD simulations
Tobias Buck, Aura Obreja, Bridget Ratcliffe +4
Recent observations of the Milky Way (MW) found an unexpected steepening of the star-forming gas metallicity gradient around the time of the Gaia-Sausage-Enceladus (GSE) merger eve…
zoomies: A tool to infer stellar age from vertical action in Gaia data
Sheila Sagear, Adrian M. Price-Whelan, Sarah Ballard +4
Stellar age measurements are fundamental to understanding a wide range of astronomical processes, including Galactic dynamics, stellar evolution, and planetary system formation. Ho…
The temporal and spatial variations of lithium abundance in the Galactic disc
Tiancheng Sun, Shaolan Bi, Xunzhou Chen +7
This study investigates the temporal and spatial variations in lithium abundance within the Milky Way using a sample of 22,034 main-sequence turn-off (MSTO) stars and subgiants, ch…
Potential Impact of the Sagittarius Dwarf Galaxy on the Formation of Young O-rich Stars
Tiancheng Sun, Shaolan Bi, Xunzhou Chen +11
The Milky Way underwent significant transformations in its early history, characterised by violent mergers and satellite galaxy accretion. However, recent observations reveal notab…
The 3D Galactocentric velocities of Kepler stars: marginalizing over missing RVs
Ruth Angus, Adrian M. Price-Whelan, Joel C. Zinn +4
Precise Gaia measurements of positions, parallaxes, and proper motions provide an opportunity to calculate 3D positions and 2D velocities (i.e. 5D phase-space) of Milky Way stars.…
Performance-Complexity Analysis for MAC ML-based Decoding with User Selection
Hsiao-feng, Lu, Petros Elia +1
This work explores the rate-reliability-complexity limits of the quasi-static K-user multiple access channel (MAC), with or without feedback. Using high-SNR asymptotics, the work f…
StarFlow: Leveraging Normalizing Flows for Stellar Age Estimation in SDSS-V DR19
Alexander Stone-Martinez, Jon A. Holtzman, Yuxi +6
Understanding the ages of stars is crucial for unraveling the formation history and evolution of our Galaxy. Traditional methods for estimating stellar ages from spectroscopic data…
Trials and Tribulations of Chemodynamical Tagging: Investigating the Recovery of Open Clusters in the Gaia DR3-GALAH DR4 Catalog
Nicholas A. Barth, David Mendez, Rana Ezzeddine +5
Chemodynamical tagging has been suggested as a powerful tool to trace stars back to their birth clusters. However, the efficacy of chemodynamical tagging as a means to recover indi…
The Twentieth Data Release of the Sloan Digital Sky Survey: First All-Sky BOSS Spectra, eROSITA-SDSS-V Mapper Coordinated Observations, and a Preview of the Local Volume Mapper
SDSS Collaboration, Mojgan Aghakhanloo, David Aguilar +273
The paper describes the twentieth data release (DR20) of the Sloan Digital Sky Survey, providing over 3 million new optical spectra from the SDSS‑V Milky Way, Black Hole, and Local…
C3PO V: Comoving stellar pairs indicate rotational spin-down drives the main-sequence Li-Dip
Qinghui Sun, Yuan-Sen Ting, Barbara J. Anthony-Twarog +4
The lithium-dip observed in mid-F dwarfs remains a long-standing challenge for stellar evolution models. We present high-precision stellar parameters and A(Li) for 22 new comoving…
ET White Paper: To Find the First Earth 2.0
Jian Ge, Hui Zhang, Weicheng Zang +163
We propose to develop a wide-field and ultra-high-precision photometric survey mission, temporarily named "Earth 2.0 (ET)". This mission is designed to measure, for the first time,…
The impact of stellar metallicity on rotation and activity evolution in the Kepler field using gyro-kinematic ages
Victor See, Yuxi, Lu +2
In recent years, there has been a push to understand how chemical composition affects the magnetic activity levels of main sequence low-mass stars. Results indicate that more metal…
Considerations for Master Protocols Using External Controls
Jie Chen, Xiaoyun, Li +7
There has been an increasing use of master protocols in oncology clinical trials because of its efficiency and flexibility to accelerate cancer drug development. Depending on the s…
LMC Stars and Where to Find Them: Inferring Birth Radii for External Galaxies
Yuxi, Lu, Tobias Buck +5
It is well known that stars move away from their birth location over time via radial migration. This dynamical process makes computing the correct chemical evolution, e.g., metalli…
When LAMOST meets Gaia DR3 Exploring the metallicity of open clusters
R. Zhang, Guo-Jian Wang, Yuxi +9
Context. Open clusters (OCs) are valuable probes of stellar population characteristics. Their age and metallicity provide insights into the chemical enrichment history of the Milky…
Revealing the Chemical Structure of the Magellanic Clouds with APOGEE. III. Abundance Gradients of the Small Magellanic Cloud
Joshua T. Povick, David L. Nidever, Pol Massana +10
We determine radial- and age-abundance gradients of the Small Magellanic Cloud (SMC) using spectra of 2,062 red giant branch (RGB) field stars observed by SDSS-IV / APOGEE-2S. With…
Spoiled for Choice? Personalized Recommendation for Healthcare Decisions: A Multi-Armed Bandit Approach
Tongxin Zhou, Yingfei Wang, Lu +2
Online healthcare communities provide users with various healthcare interventions to promote healthy behavior and improve adherence. When faced with too many intervention choices,…
Massive-Scalar Absorption by Extremal p-branes
M. Cvetic, H, Lu +1
We study the absorption probability of minimally-coupled massive scalars by extremal p-branes. In particular, we find that the massive scalar wave equation under the self-dual stri…
BenchGuard: Who Guards the Benchmarks? Automated Auditing of LLM Agent Benchmarks
Xinming Tu, Tianze Wang, Yingzhou +4
As benchmarks grow in complexity, many apparent agent failures are not failures of the agent at all - they are failures of the benchmark itself: broken specifications, implicit ass…
Exoplanet Occurrence Rate with Age for FGK Stars in Kepler
Maryum Sayeed, Ruth Angus, Travis Berger +5
We measure exoplanet occurrence rate as a function of isochrone and gyrochronology ages using confirmed and candidate planets identified in Q1-17 DR25 Kepler data. We employ Kepler…