A Grid of Model Contribution Functions and Spectra: to help with the interpretation of time-resolved observations of brown dwarfs

Abstract

OVERVIEW This Zenodo record provides a grid of thermal emission spectra and their corresponding thermal-emission contribution-function summaries (average emission pressures indicating where the observed flux originates) for non-irradiated substellar objects in chemical equilibrium, as described in Phillippe et al. (2026). Models were generated using the cloud microphysics code VIRGA v0.0 (Batalha et al. 2026; Code on Zenodo: Batalha et al. 2020) together with radiative transfer via PICASO v3.2 (Mukherjee et al. 2023; Code on Zenodo: Batalha et al. 2024), using pre-computed temperature–pressure (TP) structures from the Sonora Bobcat (Marley et al. 2021a; Data on Zenodo: Marley et al. 2021b) and Sonora Diamondback (Morley et al. 2024a; Data on Zenodo: Morley et al. 2024b) grids. All models assume solar metallicity ([M/H] = 0) and solar C/O (C/O = 0.458). GRID COVERAGE Effective temperature (Teff): 500–2000 K (Δ T_eff = 100 K) Surface gravity: 3.5 <= log g (cgs) <= 5.5 (Δ log g = 0.5) Wavelength range: 0.5–30 µm Includes cloud-free and cloudy atmospheres (cloudy models parameterized by f_sed and Kzz). Spectral resolving power (R ≡ λ/Δλ): R~5000 Important filename convention (TP-profile family) Filenames containing SonDiam correspond to models with 900–2000 K. Filenames containing SonBob correspond to models with Teff <= 900 K. FILE NAMING CONVENTION Filenames encode the model setup and parameters. Examples: Cloud-free spectrumBD_cfree_wavlen_30_SonBob_0_R5000_500_3.5spect.txt→ cloud-free model, wavelength grid out to 30 µm, SonBob TP, R~5000, T_eff=500 K, log g=3.5. Cloudy spectrumBD_cldy_wavlen_30_SonBob_fs1_kz1e6_R5000_500_5.0spect.txt→ cloudy model with f_sed = 1 and K_zz = 1e6 cm²/s, otherwise as above. Notes on tags: cfree / cldy = cloud-free / cloudy wavlen_30 = wavelength range 0.5–30 µm R5000 = spectral resolving power R ≡ λ/Δλ fs# = sedimentation efficiency parameter (cloudy only). 1, 2, 3, 4, and 8 kz# = eddy diffusion coefficient Kzz in cm²/s (cloudy only). 1e6 - 1e11; where cloud condensation meets τ > 0.1 DATA PRODUCTS 1) SPECTRA (*spect.txt) Two-column ASCII tables: Column 1: Wavelength (µm) Column 2: Flux (erg cm^-2 s^-1 cm^-1) — as written in the file header 2) EMISSION CONTRIBUTION FUNCTION SUMMARIES (*.txt without spect) Four-column ASCII tables: Column 1: Wavelength (µm) Column 2: Ave_Press = characteristic/average emission pressure Column 3: Error_upper = upper bound on the characteristic pressure Column 4: Error_lower = lower bound on the characteristic pressure Error bounds are defined by the pressure range containing ~95% of the emitted flux. Definitions of how the characteristic pressure and bounds are computed follow Phillippe et al. (2026). Interactive plotting and individual model downloads available at https://ltcfgrid.research.ucf.edu/ CREDITS / CITATION If you use these models, please cite: Phillippe et al. (2026) Codes/inputs used: Morley et al. (2024) for temperature–pressure (TP) structures; VIRGA (Batalha et al. 2026); and PICASO (Batalha et al. 2019, Mukherjee et al. 2023; and references therein).