Year: 2026
Type: article
Abstract: Galactic archaeology relies on stellar kinematics and chemical abundances to identify various stellar populations and associations. With JWST, Galactic archaeology of ancient metal-poor brown dwarfs is now possible through high-sensitivity, medium-resolution spectroscopy. We present the first metal-poor brown dwarf radial velocity (RV) survey using JWST/NIRSpec G395H spectra ( λ /Δ λ ∼ 3000) for a sample of 23 LTY dwarfs across a wide range of temperatures and metallicities. We introduce a forward-modeling framework to measure robust RVs for brown dwarfs by focusing on the CO fundamental band at ∼4.5 μ m. By comparing to sources with existing high-resolution RV measurements, we demonstrate that G395H RVs can achieve a systematic uncertainty of 5 km s −1 , sufficient to examine their Galactic space motions. We identify kinematic members of the Milky Way’s thin disk, thick disk, and halo populations in this sample. We also confirm WISE J155349.98+693355.2 as likely associated with the Gaia–Enceladus merger remnant, and 2MASS J05325346+8246465 is likely associated with the Thamnos stream. Our study systematically demonstrates that JWST G395H spectroscopy can provide robust RVs in addition to detailed chemical abundances, necessary for Galactic archaeology studies. Future discoveries and characterization of brown dwarfs associated with Galactic halo substructures and streams will enable a stringent test of stellar/substellar formation and evolutionary models for diverse metallicities.
Source: The Astrophysical Journal
Authors: Chih-Chun Hsu, Christopher A. Theissen, Adam J. Burgasser, Adam C. Schneider, Christian Aganze, Aaron M. Meisner, Jonathan Gagné, Nicolas Lodieu, ZengHua Zhang, Genaro Suárez, Eileen C. Gonzales, Jacqueline K. Faherty, Jason J. 劲飞 Wang 王, Stanimir A. Metchev, Dan Caselden, Michael C. Cushing, Roman Gerasimov
Institutions: Northwestern University, University of California San Diego, United States Naval Observatory, Stanford University, Harvard University, Center for Astrophysics Harvard & Smithsonian, NSF NOIRLab, Université de Montréal, Universidad de La Laguna, Instituto de Astrofísica de Canarias, Nanjing University, San Francisco State University, Western University, University of Toledo, University of Notre Dame
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $4,499
OpenAlex ID: W7214508223