The First JWST Spectral Energy Distribution of a Y Dwarf

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

Research output: Contribution to journalArticlepeer-review

6 Scopus citations


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.

Original languageEnglish (US)
Article numberL48
JournalAstrophysical Journal Letters
Issue number2
StatePublished - Jul 1 2023

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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