The Sonora Substellar Atmosphere Models. IV. Elf Owl: Atmospheric Mixing and Chemical Disequilibrium with Varying Metallicity and C/O Ratios
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| Autores principales: | , , , , , , , , , |
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| Formato: | Preprint |
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2024
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| _version_ | 1866913437604380672 |
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| author | Mukherjee, Sagnick Fortney, Jonathan J. Morley, Caroline V. Batalha, Natasha E. Marley, Mark S. Karalidi, Theodora Visscher, Channon Lupu, Roxana Freedman, Richard Gharib-Nezhad, Ehsan |
| author_facet | Mukherjee, Sagnick Fortney, Jonathan J. Morley, Caroline V. Batalha, Natasha E. Marley, Mark S. Karalidi, Theodora Visscher, Channon Lupu, Roxana Freedman, Richard Gharib-Nezhad, Ehsan |
| contents | Disequilibrium chemistry due to vertical mixing in the atmospheres of many brown dwarfs and giant exoplanets is well-established. Atmosphere models for these objects typically parameterize mixing with the highly uncertain $K_{\rm zz}$ diffusion parameter. The role of mixing in altering the abundances of C-N-O-bearing molecules has mostly been explored for solar composition atmospheres. However, atmospheric metallicity and the C/O ratio also impact atmospheric chemistry. Therefore, we present the \texttt{Sonora Elf Owl} grid of self-consistent cloud-free 1D radiative-convective equilibrium model atmospheres for JWST observations, which includes a variation of $K_{\rm zz}$ across several orders of magnitude and also encompasses sub-solar to super-solar metallicities and C/O ratios. We find that the impact of $K_{\rm zz}$ on the $T(P)$ profile and spectra is a strong function of both $T_{\rm eff}$ and metallicity. For metal-poor objects $K_{\rm zz}$ has large impacts on the atmosphere at significantly higher $T_{\rm eff}$ compared to metal-rich atmospheres where the impact of $K_{\rm zz}$ is seen to occur at lower $T_{\rm eff}$. We identify significant spectral degeneracies between varying $K_{\rm zz}$ and metallicity in multiple wavelength windows, in particular at 3-5 $μ$m. We use the \texttt{Sonora Elf Owl} atmospheric grid to fit the observed spectra of a sample of 9 early to late T- type objects from $T_{\rm eff}=550-1150$ K. We find evidence for very inefficient vertical mixing in these objects with inferred $K_{\rm zz}$ values lying in the range between $\sim$ 10$^1$-10$^4$ cm$^2$s$^{-1}$. Using self-consistent models, we find that this slow vertical mixing is due to the observations probing mixing in the deep detached radiative zone in these atmospheres. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2402_00756 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | The Sonora Substellar Atmosphere Models. IV. Elf Owl: Atmospheric Mixing and Chemical Disequilibrium with Varying Metallicity and C/O Ratios Mukherjee, Sagnick Fortney, Jonathan J. Morley, Caroline V. Batalha, Natasha E. Marley, Mark S. Karalidi, Theodora Visscher, Channon Lupu, Roxana Freedman, Richard Gharib-Nezhad, Ehsan Earth and Planetary Astrophysics Solar and Stellar Astrophysics Disequilibrium chemistry due to vertical mixing in the atmospheres of many brown dwarfs and giant exoplanets is well-established. Atmosphere models for these objects typically parameterize mixing with the highly uncertain $K_{\rm zz}$ diffusion parameter. The role of mixing in altering the abundances of C-N-O-bearing molecules has mostly been explored for solar composition atmospheres. However, atmospheric metallicity and the C/O ratio also impact atmospheric chemistry. Therefore, we present the \texttt{Sonora Elf Owl} grid of self-consistent cloud-free 1D radiative-convective equilibrium model atmospheres for JWST observations, which includes a variation of $K_{\rm zz}$ across several orders of magnitude and also encompasses sub-solar to super-solar metallicities and C/O ratios. We find that the impact of $K_{\rm zz}$ on the $T(P)$ profile and spectra is a strong function of both $T_{\rm eff}$ and metallicity. For metal-poor objects $K_{\rm zz}$ has large impacts on the atmosphere at significantly higher $T_{\rm eff}$ compared to metal-rich atmospheres where the impact of $K_{\rm zz}$ is seen to occur at lower $T_{\rm eff}$. We identify significant spectral degeneracies between varying $K_{\rm zz}$ and metallicity in multiple wavelength windows, in particular at 3-5 $μ$m. We use the \texttt{Sonora Elf Owl} atmospheric grid to fit the observed spectra of a sample of 9 early to late T- type objects from $T_{\rm eff}=550-1150$ K. We find evidence for very inefficient vertical mixing in these objects with inferred $K_{\rm zz}$ values lying in the range between $\sim$ 10$^1$-10$^4$ cm$^2$s$^{-1}$. Using self-consistent models, we find that this slow vertical mixing is due to the observations probing mixing in the deep detached radiative zone in these atmospheres. |
| title | The Sonora Substellar Atmosphere Models. IV. Elf Owl: Atmospheric Mixing and Chemical Disequilibrium with Varying Metallicity and C/O Ratios |
| topic | Earth and Planetary Astrophysics Solar and Stellar Astrophysics |
| url | https://arxiv.org/abs/2402.00756 |