Implementation of Aerosol Mie Scattering in POSEIDON with Application to the Hot Jupiter HD 189733 b’s Transmission, Emission, and Reflected Light Spectrum
Aerosols are a ubiquitous feature of planetary atmospheres and leave clear spectral imprints in exoplanet spectra. Pre-JWST, exoplanet retrieval frameworks mostly adopted simple parametric approximations. With JWST, we now have access to mid-infrared wavelengths where aerosols have detectable compos...
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2024-01-01
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| Online Access: | https://doi.org/10.3847/1538-4357/ad8575 |
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| author | Elijah Mullens Nikole K. Lewis Ryan J. MacDonald |
| author_facet | Elijah Mullens Nikole K. Lewis Ryan J. MacDonald |
| author_sort | Elijah Mullens |
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| description | Aerosols are a ubiquitous feature of planetary atmospheres and leave clear spectral imprints in exoplanet spectra. Pre-JWST, exoplanet retrieval frameworks mostly adopted simple parametric approximations. With JWST, we now have access to mid-infrared wavelengths where aerosols have detectable composition-specific resonance features. Here, we implement new features into the open-source atmospheric retrieval code POSEIDON to account for the complex scattering, reflection, and absorption properties of Mie-scattering aerosols. We provide an open-source database of these Mie-scattering cross sections and optical properties. We also extend the radiative transfer and retrieval functionality in POSEIDON to include multiple scattering reflection and emission spectroscopy. We demonstrate these new retrieval capabilities on archival Hubble and Spitzer transmission and secondary-eclipse spectra of the hot Jupiter HD 189733 b. We find that a high-altitude, low-density, and thin slab composed of submicron particles is necessary to fit HD 189733 b’s transmission spectrum, with multiple aerosol species providing a good fit. We additionally retrieve a subsolar H _2 O abundance, a subsolar K abundance, and do not detect CO _2 . Our joint thermal and reflection retrievals of HD 189733 b’s secondary-eclipse spectrum, however, finds no evidence of dayside aerosols, a subsolar dayside H _2 O abundance, enhanced CO _2 , or slightly subsolar alkali abundances. We additionally explore how retrieval model choices such as cloud parameterization, aerosol species and properties, and thermal structure parameterization affect retrieved atmospheric properties. Upcoming JWST data for hot Jupiters such as HD 189733 b will be well suited to enable deeper exploration of aerosol properties, allowing the formulation of a self-consistent, multidimensional picture of cloud formation processes. |
| format | Article |
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| institution | OA Journals |
| issn | 1538-4357 |
| language | English |
| publishDate | 2024-01-01 |
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| series | The Astrophysical Journal |
| spelling | doaj-art-7dfa880f04124436a0a9977c03e7bfbd2025-08-20T02:19:38ZengIOP PublishingThe Astrophysical Journal1538-43572024-01-01977110510.3847/1538-4357/ad8575Implementation of Aerosol Mie Scattering in POSEIDON with Application to the Hot Jupiter HD 189733 b’s Transmission, Emission, and Reflected Light SpectrumElijah Mullens0https://orcid.org/0000-0003-0814-7923Nikole K. Lewis1https://orcid.org/0000-0002-8507-1304Ryan J. MacDonald2https://orcid.org/0000-0003-4816-3469Department of Astronomy and Carl Sagan Institute, Cornell University , 122 Sciences Drive, Ithaca, NY 14853, USADepartment of Astronomy and Carl Sagan Institute, Cornell University , 122 Sciences Drive, Ithaca, NY 14853, USADepartment of Astronomy, University of Michigan , 1085 S. University Avenue, Ann Arbor, MI 48109, USAAerosols are a ubiquitous feature of planetary atmospheres and leave clear spectral imprints in exoplanet spectra. Pre-JWST, exoplanet retrieval frameworks mostly adopted simple parametric approximations. With JWST, we now have access to mid-infrared wavelengths where aerosols have detectable composition-specific resonance features. Here, we implement new features into the open-source atmospheric retrieval code POSEIDON to account for the complex scattering, reflection, and absorption properties of Mie-scattering aerosols. We provide an open-source database of these Mie-scattering cross sections and optical properties. We also extend the radiative transfer and retrieval functionality in POSEIDON to include multiple scattering reflection and emission spectroscopy. We demonstrate these new retrieval capabilities on archival Hubble and Spitzer transmission and secondary-eclipse spectra of the hot Jupiter HD 189733 b. We find that a high-altitude, low-density, and thin slab composed of submicron particles is necessary to fit HD 189733 b’s transmission spectrum, with multiple aerosol species providing a good fit. We additionally retrieve a subsolar H _2 O abundance, a subsolar K abundance, and do not detect CO _2 . Our joint thermal and reflection retrievals of HD 189733 b’s secondary-eclipse spectrum, however, finds no evidence of dayside aerosols, a subsolar dayside H _2 O abundance, enhanced CO _2 , or slightly subsolar alkali abundances. We additionally explore how retrieval model choices such as cloud parameterization, aerosol species and properties, and thermal structure parameterization affect retrieved atmospheric properties. Upcoming JWST data for hot Jupiters such as HD 189733 b will be well suited to enable deeper exploration of aerosol properties, allowing the formulation of a self-consistent, multidimensional picture of cloud formation processes.https://doi.org/10.3847/1538-4357/ad8575ExoplanetsExoplanet atmospheresExoplanet atmospheric compositionHot JupitersTransmission spectroscopySpectroscopy |
| spellingShingle | Elijah Mullens Nikole K. Lewis Ryan J. MacDonald Implementation of Aerosol Mie Scattering in POSEIDON with Application to the Hot Jupiter HD 189733 b’s Transmission, Emission, and Reflected Light Spectrum The Astrophysical Journal Exoplanets Exoplanet atmospheres Exoplanet atmospheric composition Hot Jupiters Transmission spectroscopy Spectroscopy |
| title | Implementation of Aerosol Mie Scattering in POSEIDON with Application to the Hot Jupiter HD 189733 b’s Transmission, Emission, and Reflected Light Spectrum |
| title_full | Implementation of Aerosol Mie Scattering in POSEIDON with Application to the Hot Jupiter HD 189733 b’s Transmission, Emission, and Reflected Light Spectrum |
| title_fullStr | Implementation of Aerosol Mie Scattering in POSEIDON with Application to the Hot Jupiter HD 189733 b’s Transmission, Emission, and Reflected Light Spectrum |
| title_full_unstemmed | Implementation of Aerosol Mie Scattering in POSEIDON with Application to the Hot Jupiter HD 189733 b’s Transmission, Emission, and Reflected Light Spectrum |
| title_short | Implementation of Aerosol Mie Scattering in POSEIDON with Application to the Hot Jupiter HD 189733 b’s Transmission, Emission, and Reflected Light Spectrum |
| title_sort | implementation of aerosol mie scattering in poseidon with application to the hot jupiter hd 189733 b s transmission emission and reflected light spectrum |
| topic | Exoplanets Exoplanet atmospheres Exoplanet atmospheric composition Hot Jupiters Transmission spectroscopy Spectroscopy |
| url | https://doi.org/10.3847/1538-4357/ad8575 |
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