J. Kirkpatrick

SMDET-1: a Nearby Y Dwarf Candidate

Aaron M. Meisner, Dan Caselden, Federico Marocco +11

We present the discovery of SMDET-1, a red, fast-moving object ( $μ \approx 1.3$ "/yr) identified in time-resolved unWISE coadds using a pixel-level deep learning methodology called S…

SPHEREx 0.75 to 5 $μ$ m Spectra for a Sequence of Nearby Brown Dwarfs

Zafar Rustamkulov, J. Kirkpatrick, Rachel Akeson +21

The SPHEREx all-sky survey has now measured the R $\sim$ 40-100 infrared spectra of thousands of nearby brown dwarfs in the chemically rich 0.75-5 $μ$ m range. The survey's wide spect…

A SPHEREx Pipeline and Spectral Library for Ultracool Dwarfs

Jonathan Gagné, Jacqueline K. Faherty, Azul Ruiz Diaz +72

We present a Python spectrophotometry extraction tool tailored for fast-moving point sources detected in the SPHEREx mission, and use it to construct a set of 0.75-5.0 $μ$ m low-res…

astro-ph.SR2026★ 1 cited

Spectroscopic Characterization of WD J000801.25-350450 and its Two Co-Moving Companions

Peter A. Jałowiczor, Thomas P. Bickle, J. Davy Kirkpatrick +18

We present new spectroscopic data for Gaia DR3 2309499817384726016 (WD0008-350A) and its two wide, co-moving, low-mass companions. We confirm the white dwarf is a hydrogen-rich DA,…

A Comprehensive Atmospheric Retrieval Analysis of 22 James Webb Space Telescope Spectral Energy Distributions of Cool Brown Dwarfs

Harshil Kothari, Michael C. Cushing, Samuel A. Beiler +5

We present a uniform atmospheric retrieval analysis of 22 late-T and Y-type brown dwarfs within 20 pc, observed with the James Webb Space Telescope NIRSpec PRISM and MIRI LRS. This…

Three Thousand Motion-Confirmed L and T Dwarf Candidates from the Backyard Worlds:~Planet 9 Citizen Science Project

Adam C. Schneider, Marc J. Kuchner, Jacqueline K. Faherty +73

The Backyard Worlds: Planet 9 citizen science project uses data from the Wide-field Infrared Survey Explorer to detect infrared objects with significant motion. In this work, we pr…

Spitzer + HST parallaxes of 13 late T and Y dwarfs

Federico Marocco, J. Davy Kirkpatrick, Richard L. Smart +13

We present astrometric measurements for 13 cold brown dwarfs in the solar neighborhood (d < 20pc). By combining archival Spitzer data with our own Hubble Space Telescope (HST) obse…

Parallaxes, Proper Motions, and Near-Infrared Photometry for 173 L and T Dwarfs From The US Naval Observatory Infrared Astrometry Program

Frederick J. Vrba, Adam C. Schneider, Jeffrey A. Munn +11

We present near-infrared parallax and proper motion astrometry for 74 L-dwarfs and 99 T-dwarfs, as single objects or in binary systems, obtained with the ASTROCAM astrometric image…

A search for late-type brown dwarfs in the Euclid Quick Data Release 1

Frank Kiwy, J. Davy Kirkpatrick, Adam C. Schneider +9

We present the identification and characterization of 15 mid-to-late T dwarf candidates in the Euclid Quick Release 1 (Q1) dataset, based on a combined photometric and spectroscopi…

astro-ph.EP2025★ 12 cited

High Proper Motion Discoveries from the UKIRT Hemisphere Survey

Wings Zhang, Adam C. Schneider, Thomas P. Bickle +31

We used the third data release of the UKIRT Hemisphere Survey to locate previously unrecognized high proper motion objects. We identify a total of 127 new discoveries with total pr…

Silicate Precursor Silane detected in Cold Low-Metallicity Brown Dwarf

Jacqueline K. Faherty, Aaron M. Meisner, Ben Burningham +28

Within 20 pc of the Sun there are currently 29 known cold brown dwarfs, sources with measured distances and an estimated effective temperature between that of Jupiter (170K) and ~5…

astro-ph.SR2025★ 3 cited

Diversity of Cold Worlds: A Near Complete Spectral Energy Distribution for 2MASS J04151954-0935066 using JWST

Sherelyn Alejandro Merchan, Jacqueline K. Faherty, Genaro Suárez +25

We present the a near complete spectral energy distribution (SED) for an extrasolar world: the T8 brown dwarf 2MASS~J04151954 $-$ 0935066. Spanning from optical to mid-infrared (0.7-…

Unveiling the Infrared Excess of SIPS J2045-6332: Evidence for a Young Stellar Object with Potential Low-Mass Companion

Michiharu Hyogo, Thomas P. Bickle, Joseph R. Biggs +20

The Disk Detective project, a citizen science initiative, aims to identify circumstellar discs around stars by detecting objects with infrared (IR) excess using data from the Wide-…

The Diversity of Cold Worlds: a blended-light binary straddling the T/Y transition in brown dwarfs

Daniella C. Bardalez Gagliuffi, Jacqueline K. Faherty, Genaro Suarez +22

We present the first brown dwarf spectral binary characterized with JWST: WISE J014656.66+423410.0, the coldest blended-light brown dwarf binary straddling the T/Y transition. We o…

New Ultracool Companions to Nearby White Dwarfs

Alexia Bravo, Adam C. Schneider, Sarah Casewell +15

We conducted a search for new ultracool companions to nearby white dwarfs using multiple methods, including the analysis of colors and examination of images in both the optical and…

New Cold Subdwarf Discoveries from Backyard Worlds and a Metallicity Classification System for T Subdwarfs

Adam J. Burgasser, Adam C. Schneider, Aaron M. Meisner +36

We report the results of a spectroscopic survey of candidate T subdwarfs identified by the Backyard Worlds: Planet 9 program. Near-infrared spectra of 31 sources with red $J - W 2$ co…

Discovery of 118 New Ultracool Dwarf Candidates Using Machine Learning Techniques

Hunter Brooks, Dan Caselden, J. Davy Kirkpatrick +44

We present the discovery of 118 new ultracool dwarf candidates, discovered using a new machine learning tool, named \texttt{SMDET}, applied to time series images from the Wide-fiel…

astro-ph.EP2024

A Tale of Two Molecules: The Underprediction of CO $_{2}$ and Overprediction of PH $_{3}$ in Late T and Y Dwarf Atmospheric Models

Samuel A. Beiler, Sagnick Mukherjee, Michael C. Cushing +5

The sensitivity and spectral coverage of JWST is enabling us to test our assumptions of ultracool dwarf atmospheric chemistry, especially with regards to the abundances of phosphin…

Precise Bolometric Luminosities and Effective Temperatures of 23 late-T and Y dwarfs Obtained with JWST

Samuel A. Beiler, Michael C. Cushing, J. Davy Kirkpatrick +5

We present infrared spectral energy distributions of 23 late-type T and Y dwarfs obtained with the James Webb Space Telescope. The spectral energy distributions consist of NIRSpec…

Discovery of a Hypervelocity L Subdwarf at the Star/Brown Dwarf Mass Limit

Adam J. Burgasser, Roman Gerasimov, Kyle Kremer +18

We report the discovery of a high velocity, very low-mass star or brown dwarf whose kinematics suggest it is unbound to the Milky Way. CWISE J124909.08+362116.0 was identified by c…

Simulating Brown Dwarf Observations for Various Mass Functions, Birthrates, and Low-mass Cutoffs

Yadukrishna Raghu, J. Davy Kirkpatrick, Federico Marocco +12

After decades of brown dwarf discovery and follow-up, we can now infer the functional form of the mass distribution within 20 parsecs, which serves as a constraint on star formatio…

Probing the Heights and Depths of Y Dwarf Atmospheres: A Retrieval Analysis of the JWST Spectral Energy Distribution of WISE J035934.06 $-$ 540154.6

Harshil Kothari, Michael C. Cushing, Ben Burningham +5

We present an atmospheric retrieval analysis of the Y0 brown dwarf WISE J035934.06 $-$ 540154.6 using the low-resolution 0.96--12 $μ$ m JWST spectrum presented in \citet{Beiler_2023}.…