2003/05/09 by N. Gorlova, Nadya Gorlova, Michael R. Meyer +4 · 7 citations
Physics and Astronomy · #Astro and Planetary Science #Astrophysics and Star Formation Studies #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/376730
published as Astrophys.J. 593 (2003) 1074-1092 · Accepted to ApJ, 44 pages & 10 figures, preliminary results reported in astro-ph/0208221
arxiv created 2003/05/09 · openalex publication_date 2003/08/11 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/01
We investigate the sensitivity to temperature and gravity of the strong absorption features in the J - and K -band spectra of substellar objects. We compare the spectra of giants and young M dwarfs (of low gravity) to field M and L dwarfs (of high gravity) and to model spectra from the Lyon group. We find that low-resolution spectra of M4-M9 stars and young brown dwarfs at R ~ 350 and signal-to-noise ratios greater than 70 can determine the spectral type to a precision of ±1 subtype using the H 2 O and CO bands and can measure the surface gravity to ±0.5 dex using the atomic lines of K I and Na I. This result points toward the development of photometric spectral indices to separate low-mass members from foreground and background objects in young clusters and associations. We also emphasize the complexity of the interpretation of the empirical quantities (e.g., spectral types) in terms of the physical variables (e.g., temperature, opacities) in the cool atmospheres of young brown dwarfs.