Paper

Early results from GLASS-JWST. XIII. A faint, distant, and cold brown dwarf

Wang, X, Vanzella, E, Grillo, C, Merlin, E, Glazebrook, K, Bonchi, A, Polenta, G, Nonino, M, Treu, T, Mercurio, A, Rosati, P, Burgasser, A J, Morishita, T, Santini, P, Nanayakkara, T, Bradac, M, Vulcani, B, Castellano, M, Paris, D, Lepinzan, M, Fontana, A

2022

Overview

We present the serendipitous discovery of a late T-type brown dwarf candidate in JWST NIRCam observations of the Early Release Science Abell 2744 parallel field. The discovery was enabled by the sensitivity of JWST at 4~\\(\\mu\\)m wavelengths and the panchromatic 0.9--4.5~\\(\\mu\\)m coverage of the spectral energy distribution. The unresolved point source has magnitudes F115W = 27.95\\(\\pm\\)0.15 and F444W = 25.84\\(\\pm\\)0.01 (AB), and its F115W\\(-\\)F444W and F356W\\(-\\)F444W colors match those expected for other, known T dwarfs. We can exclude it as a reddened background star, high redshift quasar, or very high redshift galaxy. Comparison with stellar atmospheric models indicates a temperature of \\(T_{eff}\\) \\(\\approx\\) 600~K and surface gravity \\(\\log{g}\\) \\(\\approx\\) 5, implying a mass of 0.03~M\\(_{\\odot}\\) and age of 5~Gyr. We estimate the distance of this candidate to be 570--720~pc in a direction perpendicular to the Galactic plane, making it a likely thick disk or halo brown dwarf. These observations underscore the power of JWST to probe the very low-mass end of the substellar mass function in the Galactic thick disk and halo.

• Publisher: Cornell University Library, arXiv.org
• Subject: Astronomical models / Atmospheric models / Brown dwarf stars / Quasars / Red shift / Spectral energy distribution / Stellar atmospheres