549 citations · 2.1k across the 75 of their papers we have counts for
81 papers
What does self-supervision add to engineered features for stellar light curves?
Zijun Liu, Yue Ma, Christopher A. Theissen
TESS light curves encode a star's pulsation, rotation, binarity and oscillations, among other physical properties, but the survey produces far more light curves than can be labelle…
JWST Observations of the Metal-poor T Dwarf WISEA J155349.96+693355.2: The First Brown Dwarf Associated with the Gaia-Enceladus Milky Way Substructure
Aaron M. Meisner, Adam J. Burgasser, Chih-Chun Hsu +15
We present JWST NIRSpec and MIRI observations of the metal-poor T dwarf WISEA J155349.96+693355.2. The combined NIRSpec/prism plus MIRI/LRS spectrum (R ~ 100) provides 0.6-12 m…
Metal-poor Brown Dwarf Kinematics from JWST NIRSpec Spectroscopy
Chih-Chun Hsu, Christopher A. Theissen, Adam J. Burgasser +14
Galactic archaeology relies on stellar kinematics and chemical abundances to identify various stellar populations and associations. With JWST, Galactic archaeology of ancient metal…
The Dyn-Atmo Survey: JWST/NIRSpec spectroscopy of dynamical benchmark GJ 758 B
Alexander Madurowicz, Emily Rickman, Daniella Bardalez Gagliuffi +22
We present new JWST/NIRSpec IFU high contrast spectroscopic observations of the brown dwarf companion GJ 758 B. Extensive radial velocity monitoring of the primary has enabled high…
The Dyn-Atmo Survey: High-contrast Imaging Spectroscopy of the Substellar Companion HD 13724 B with the JWST NIRSpec IFU
Kielan K. W. Hoch, Alex Madurowicz, Evert Nasedkin +22
We present the first spectral analysis from the JWST Cycle 3 GO Program #6362, the Dyn-Atmo Survey of dynamical-atmospheric benchmarks, characterizing the atmospheres of directly-i…
EncoTESS: Age-Sensitive Encodings from Raw TESS Light Curves
Phil R. Van-Lane, Joshua S. Speagle, Ryan Cloutier +3
Main sequence stars of spectral types late F through M exhibit systematic variability in photometric light curves, particularly when they are young. Rotational modulation of starsp…
A High-Resolution Spectroscopic Survey of Directly Imaged Companion Hosts: III. Characterization of the Cold Imaged Planet Hosts AF Lep A and Indi A
Aneesh Baburaj, Quinn M. Konopacky, Christopher A. Theissen +3
JWST has enabled the measurement of carbon, oxygen, and sulfur abundances in the atmospheres of directly imaged planets. Interpretation of these abundances from a planet formation…
The JWST Early Release Science Program for Direct Observations of Exoplanetary Systems VIII: patchy forsterite and enstatite clouds in the atmosphere of VHS 1256 b, retrieval lessons learned and outlook to the future
Niall Whiteford, Jacqueline K. Faherty, Ben Burningham +123
JWST defines a new era for the data-driven approach of retrieval modelling, which has become a cornerstone tool for the statistical inference of exoplanetary and brown dwarf proper…
Stellar Multiplicity of M Dwarfs with Short-period Giant Planets, and the Characterization of TOI-5628Ab
Tianjun Gan, Alexandrine L'Heureux, Charles Cadieux +33
Binary stars are ubiquitous, yet it remains unclear how wide-orbit stellar companions influence the formation of hot Jupiters, particularly around M dwarfs. Here, we first report t…
The JWST Early Release Science Program for Direct Observations of Exoplanetary Systems. VII. Molecular Mapping Performance with JWST/MIRI MRS: VHS 1256 b as a case study
Mathilde Mâlin, Anthony Boccaletti, Benjamin Charnay +29
VHS 1256 b was the first planetary-mass companion to be observed with the James Webb Space Telescope's Mid-Infrared Instrument (JWST/MIRI) using the Medium-Resolution Spectrometer…
Identifying and Characterizing Very Low Mass Spectral Blend Binaries with Machine Learning Methods
Juan Diego Draxl Giannoni, Malina Desai, Adam J. Burgasser +5
We present an approach to identifying and characterizing unresolved, very low mass spectral blend binaries composed of late-M, L, and T dwarfs using machine learning methodologies.…
A High-Resolution Spectroscopic Survey of Directly Imaged Companion Hosts: II. Diversity in C/O Ratios among Host Stars
Aneesh Baburaj, Quinn M. Konopacky, Christopher A. Theissen +2
The era of JWST has enabled measurements of abundances of elements such as C, O, and even Na, S, K, and Fe in planetary atmospheres to very high precisions (0.1 dex). Accurat…
Classifying Cool Dwarfs: Comprehensive Spectral Typing of Field and Peculiar Dwarfs Using Machine Learning
Tianxing Zhou, Christopher A. Theissen, S. Jean Feeser +4
Low-mass stars and brown dwarfs -- spectral types (SpTs) M0 and later -- play a significant role in studying stellar and substellar processes and demographics, reaching down to pla…
Silicate clouds and a circumplanetary disk in the YSES-1 exoplanet system
Kielan K. W. Hoch, Melanie Rowland, Simon Petrus +26
Young exoplanets provide a critical link between understanding planet formation and atmospheric evolution. Direct imaging spectroscopy allows us to infer the properties of young, w…
Gravity-sensitive Spectral Indices in Ultracool Dwarfs: Investigating Correlations with Metallicity and Planet Occurrence using SpeX and FIRE Observations
Fatemeh Davoudi, Benjamin V. Rackham, Julien de Wit +5
We present a near-infrared spectroscopic analysis (0.9--2.4~m) of gravity indices for 56 ultracool dwarfs (M5.5--L0), including exoplanet hosts SPECULOOS-2, SPECULOOS-3, and LHS…
Spectropolarimetric Evolution of SN 2023ixf: an Asymmetric Explosion in a Confined Aspherical Circumstellar Medium
Sergiy S. Vasylyev, Luc Dessart, Yi Yang +15
We present complete spectropolarimetric coverage of the Type II supernova (SN) 2023ixf ranging from 1 to 120 days after explosion. Polarimetry was obtained with the Kast double spe…
TOI-6478 b: a cold under-dense Neptune transiting a fully convective M dwarf from the thick disc
Madison G. Scott, Amaury H. M. J. Triaud, Khalid Barkaoui +25
Growing numbers of exoplanet detections continue to reveal the diverse nature of planetary systems. Planet formation around late-type M dwarfs is of particular interest. These syst…
SN 2023ixf in the Pinwheel Galaxy M101: From Shock Breakout to the Nebular Phase
Weikang Zheng, Luc Dessart, Alexei V. Filippenko +39
We present photometric and spectroscopic observations of SN 2023ixf covering from day one to 442 days after explosion. SN 2023ixf reached a peak -band absolute magnitude of $-18…
TOI-6508b: A massive transiting brown dwarf orbiting a low-mass star
K. Barkaoui, D. Sebastian, S. Zúñiga-Fernández +44
We report the discovery of a transiting brown dwarf orbiting a low-mass star, TOI-6508b. Today, only ~50 transiting brown dwarfs have been discovered. TOI-6508b was first detected…
HD 206893 B at High Spectral Resolution with the Keck Planet Imager and Characterizer (KPIC)
Ben Sappey, Quinn Konopacky, Clarissa R. Do O +38
We present an atmospheric characterization and orbital analysis of HD 206893 B, an exceptionally red, L/T-transition substellar companion in a multiplanetary system, via Keck Plane…
Metallicity Dependence of Giant Planets around M Dwarfs
Tianjun Gan, Christopher A. Theissen, Sharon X. Wang +2
We investigate the stellar metallicity ([Fe/H] and [M/H]) dependence of giant planets around M dwarfs by comparing the metallicity distribution of 746 field M dwarfs without known…
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 co…
A High-Resolution Spectroscopic Survey of Directly Imaged Companion Hosts: I. Determination of diagnostic stellar abundances for planet formation and composition
Aneesh Baburaj, Quinn M. Konopacky, Christopher A. Theissen +6
We present the first results of an extensive spectroscopic survey of directly imaged planet host stars. The goal of the survey is the measurement of stellar properties and abundanc…
JWST-TST High Contrast: Spectroscopic Characterization of the Benchmark Brown Dwarf HD 19467 B with the NIRSpec Integral Field Spectrograph
Kielan K. W. Hoch, Christopher A. Theissen, Travis S. Barman +14
We present the atmospheric characterization of the substellar companion HD 19467 B as part of the pioneering JWST GTO program to obtain moderate resolution spectra (R2,700, 3…