Title: The Sonora Substellar Atmosphere Models. II. Cholla: A Grid of Cloud-free, Solar Metallicity Models in Chemical Disequilibrium for the JWST Era

Journal Article · · The Astrophysical Journal
ORCiD logo [1]; ORCiD logo [2]; ORCiD logo [3]; ORCiD logo [4]; ORCiD logo [5]; ORCiD logo [6];  [7]; ORCiD logo [6]
  1. Univ. of Central Florida, Orlando, FL (United States)
  2. Univ. of Arizona, Tucson, AZ (United States)
  3. Univ. of California, Santa Cruz, CA (United States)
  4. Univ. of Texas, Austin, TX (United States)
  5. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  6. NASA Ames Research Center (ARC), Moffett Field, Mountain View, CA (United States)
  7. Dordt Univ., Sioux Center, IA (United States)
+ Show Author Affiliations

Exoplanet and brown dwarf atmospheres commonly show signs of disequilibrium chemistry. In the James Webb Space Telescope (JWST) era, high-resolution spectra of directly imaged exoplanets will allow the characterization of their atmospheres in more detail, and allow systematic tests for the presence of chemical species that deviate from thermochemical equilibrium in these atmospheres. Constraining the presence of disequilibrium chemistry in these atmospheres as a function of parameters such as their effective temperature and surface gravity will allow us to place better constraints on the physics governing these atmospheres. This paper is part of a series of works presenting the Sonora grid of atmosphere models. In this paper, we present a grid of cloud-free, solar metallicity atmospheres for brown dwarfs and wide-separation giant planets with key molecular species such as CH4, H2O, CO, and NH3 in disequilibrium. Our grid covers atmospheres with Teff ∈ [500 K, 1300 K], log g ∈ [3.0, 5.5] (cgs) and an eddy diffusion parameter of logKzz = 2,4 and 7 (cgs). We study the effect of different parameters within the grid on the temperature and composition profiles of our atmospheres. We discuss their effect on the near-infrared colors of our model atmospheres and the detectability of CH4, H2O, CO, and NH3 using the JWST. We compare our models against existing MKO and Spitzer observations of brown dwarfs and verify the importance of disequilibrium chemistry for T dwarf atmospheres. Finally, we discuss how our models can help constrain the vertical structure and chemical composition of these atmospheres.

Research Organization:
Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
Sponsoring Organization:
National Aeronautics and Space Administration (NASA); USDOE National Nuclear Security Administration (NNSA)
Grant/Contract Number:
89233218CNA000001
OSTI ID:
1865021
Report Number(s):
LA-UR-21-27722
Journal Information:
The Astrophysical Journal, Journal Name: The Astrophysical Journal Journal Issue: 2 Vol. 923; ISSN 0004-637X
Publisher:
IOP PublishingCopyright Statement
Country of Publication:
United States
Language:
English

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