2019/04/24 by Adric R. Riedel, Victoria DiTomasso, Emily L. Rice +6 · 9 citations
Mathematics · Physics and Astronomy · #Adaptive optics and wavefront sensing #Astronomy #Astrophysics #Astrophysics and Star Formation Studies #Brown dwarf #Consistency (knowledge bases) #Geometry #Lambda #Mathematics #Observatory #Optics #Physics #Proper motion #Radial velocity #Spectral line #Stars #Stellar classification #Stellar, planetary, and galactic studies #astro-ph.SR
paper · pdf · doi:10.3847/1538-3881/ab1915
published in The Astronomical Journal 157(6), 247 (Institute of Physics) · 24 pages, 10 figures, 6 tables. Accepted by AJ
arxiv created 2019/04/24 · openalex publication_date 2019/06/01 · arxiv updated 2019/07/17 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/06
Abstract We present new radial velocity (RV) measurements for 11 candidate young very-low-mass stars and brown dwarfs, with spectral types from M7 to L7. Candidate young objects were identified by features indicative of low surface gravity in their optical and/or near-infrared spectra. RV measurements are derived from high-resolution ( R = λ /Δ λ = 20,000) J -band spectra taken with NIRSPEC at the Keck Observatory. We combine RVs with proper motions and trigonometric distances to calculate three-dimensional space positions and motions and to evaluate membership probabilities for nearby young moving groups (NYMGs). We propose 2MASS J00452143+1634446 (L2 β , J = 13.06) as an RV standard given the precision and stability of measurements from three different studies. We test the precision and accuracy of our RV measurements as a function of spectral type of the comparison object, finding that RV results are essentially indistinguishable even with differences of ±5 spectral subtypes. We also investigate the strengths of gravity-sensitive K i lines at 1.24–1.25 μ m and evaluate their consistency with other age indicators. We confirm or reconfirm four brown dwarf members of NYMGs—2MASS J00452143+1634446, WISE J00470038+6803543, 2MASS J011747483403258, and 2MASS J193555952846343—and their previous age estimates. We identify one new brown dwarf member of the Carina-Near moving group, 2M2154−10. The remaining objects do not appear to be members of any known NYMGs, despite their spectral signatures of youth. These results add to the growing number of very-low-mass objects exhibiting signatures of youth that lack likely membership in a known NYMG, thereby compounding the mystery regarding local, low-density star formation.