The First JWST Spectral Energy Distribution of a Y Dwarf

July 2023 • 2023ApJ...951L..48B

Authors • Beiler, Samuel A. • Cushing, Michael C. • Kirkpatrick, J. Davy • Schneider, Adam C. • Mukherjee, Sagnick • Marley, Mark S.

Abstract • We present the first JWST spectral energy distribution of a Y dwarf. This spectral energy distribution of the Y0 dwarf WISE J035934.06-540154.6 consists of low-resolution (λ/Δλ ~100) spectroscopy from 1-12 μm and three photometric points at 15, 18, and 21 μm. The spectrum exhibits numerous fundamental, overtone, and combination rotational-vibrational bands of H2O, CH4, CO, CO2, and NH3, including the previously unidentified ν 3 band of NH3 at 3 μm. Using a Rayleigh-Jeans tail to account for the flux emerging at wavelengths greater than 21 μm, we measure a bolometric luminosity of 1.523 ± 0.090 × 1020 W. We determine a semiempirical effective temperature estimate of ${467}_{-18}^{+16}$ K using the bolometric luminosity and evolutionary models to estimate a radius. Finally, we compare the spectrum and photometry to a grid of atmospheric models and find reasonably good agreement with a model having T eff = 450 K, log g = 3.25 [cm s-2], and [M/H] = -0.3. However, the low surface gravity implies an extremely low mass of 1 M Jup and a very young age of 20 Myr, the latter of which is inconsistent with simulations of volume-limited samples of cool brown dwarfs.


IPAC Authors


Davy Kirkpatrick

Senior Scientist