Diagnosing Limb Asymmetries in Hot and Ultrahot Jupiters with High-resolution Transmission Spectroscopy
Due to their likely tidally synchronized nature, (ultra)hot Jupiter atmospheres should experience strongly spatially heterogeneous instellation. The large irradiation contrast and resulting atmospheric circulation induce temperature and chemical gradients that can produce asymmetries across the east...
| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
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IOP Publishing
2023-01-01
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| Series: | The Astrophysical Journal |
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| Online Access: | https://doi.org/10.3847/1538-4357/acb141 |
| _version_ | 1797404752081846272 |
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| author | Arjun B. Savel Eliza M.-R. Kempton Emily Rauscher Thaddeus D. Komacek Jacob L. Bean Matej Malik Isaac Malsky |
| author_facet | Arjun B. Savel Eliza M.-R. Kempton Emily Rauscher Thaddeus D. Komacek Jacob L. Bean Matej Malik Isaac Malsky |
| author_sort | Arjun B. Savel |
| collection | DOAJ |
| description | Due to their likely tidally synchronized nature, (ultra)hot Jupiter atmospheres should experience strongly spatially heterogeneous instellation. The large irradiation contrast and resulting atmospheric circulation induce temperature and chemical gradients that can produce asymmetries across the eastern and western limbs of these atmospheres during transit. By observing an (ultra)hot Jupiter’s transmission spectrum at high spectral resolution, these asymmetries can be recovered—namely through net Doppler shifts originating from the exoplanet’s atmosphere yielded by cross-correlation analysis. Given the range of mechanisms at play, identifying the underlying cause of observed asymmetry is nontrivial. In this work, we explore sources and diagnostics of asymmetries in high-resolution cross-correlation spectroscopy of hot and ultrahot Jupiters using both parameterized and self-consistent atmospheric models. If an asymmetry is observed, we find that it can be difficult to attribute it to equilibrium chemistry gradients because many other processes can produce asymmetries. Identifying a molecule that is chemically stable over the temperature range of a planetary atmosphere can help establish a baseline to disentangle the various potential causes of limb asymmetries observed in other species. We identify CO as an ideal molecule, given its stability over nearly the entirety of the ultrahot Jupiter temperature range. Furthermore, we find that if limb asymmetry is due to morning terminator clouds, blueshifts for a number of species should decrease during transit. Finally, by comparing our forward models to those of Kesseli et al., we demonstrate that binning high-resolution spectra into two phase bins provides a desirable trade-off between maintaining signal to noise and resolving asymmetries. |
| first_indexed | 2024-03-09T03:00:35Z |
| format | Article |
| id | doaj.art-08e8a6ad1c244ca99d9b2d5d6999b88d |
| institution | Directory Open Access Journal |
| issn | 1538-4357 |
| language | English |
| last_indexed | 2024-03-09T03:00:35Z |
| publishDate | 2023-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Astrophysical Journal |
| spelling | doaj.art-08e8a6ad1c244ca99d9b2d5d6999b88d2023-12-04T16:37:31ZengIOP PublishingThe Astrophysical Journal1538-43572023-01-0194419910.3847/1538-4357/acb141Diagnosing Limb Asymmetries in Hot and Ultrahot Jupiters with High-resolution Transmission SpectroscopyArjun B. Savel0https://orcid.org/0000-0002-2454-768XEliza M.-R. Kempton1https://orcid.org/0000-0002-1337-9051Emily Rauscher2https://orcid.org/0000-0003-3963-9672Thaddeus D. Komacek3https://orcid.org/0000-0002-9258-5311Jacob L. Bean4https://orcid.org/0000-0003-4733-6532Matej Malik5https://orcid.org/0000-0002-2110-6694Isaac Malsky6https://orcid.org/0000-0003-0217-3880Center for Computational Astrophysics, Flatiron Institute , New York, NY 10010, USA ; asavel@umd.edu; Astronomy Department, University of Maryland , College Park, 4296 Stadium Drive, College Park, MD 207842, USAAstronomy Department, University of Maryland , College Park, 4296 Stadium Drive, College Park, MD 207842, USADepartment of Astronomy, University of Michigan , 1085 South University Avenue, Ann Arbor, MI 48109, USAAstronomy Department, University of Maryland , College Park, 4296 Stadium Drive, College Park, MD 207842, USADepartment of Astronomy & Astrophysics, University of Chicago , Chicago, IL 60637, USAAstronomy Department, University of Maryland , College Park, 4296 Stadium Drive, College Park, MD 207842, USADepartment of Astronomy, University of Michigan , 1085 South University Avenue, Ann Arbor, MI 48109, USADue to their likely tidally synchronized nature, (ultra)hot Jupiter atmospheres should experience strongly spatially heterogeneous instellation. The large irradiation contrast and resulting atmospheric circulation induce temperature and chemical gradients that can produce asymmetries across the eastern and western limbs of these atmospheres during transit. By observing an (ultra)hot Jupiter’s transmission spectrum at high spectral resolution, these asymmetries can be recovered—namely through net Doppler shifts originating from the exoplanet’s atmosphere yielded by cross-correlation analysis. Given the range of mechanisms at play, identifying the underlying cause of observed asymmetry is nontrivial. In this work, we explore sources and diagnostics of asymmetries in high-resolution cross-correlation spectroscopy of hot and ultrahot Jupiters using both parameterized and self-consistent atmospheric models. If an asymmetry is observed, we find that it can be difficult to attribute it to equilibrium chemistry gradients because many other processes can produce asymmetries. Identifying a molecule that is chemically stable over the temperature range of a planetary atmosphere can help establish a baseline to disentangle the various potential causes of limb asymmetries observed in other species. We identify CO as an ideal molecule, given its stability over nearly the entirety of the ultrahot Jupiter temperature range. Furthermore, we find that if limb asymmetry is due to morning terminator clouds, blueshifts for a number of species should decrease during transit. Finally, by comparing our forward models to those of Kesseli et al., we demonstrate that binning high-resolution spectra into two phase bins provides a desirable trade-off between maintaining signal to noise and resolving asymmetries.https://doi.org/10.3847/1538-4357/acb141Exoplanet atmospheric compositionRadiative transfer simulationsHigh resolution spectroscopyHot Jupiters |
| spellingShingle | Arjun B. Savel Eliza M.-R. Kempton Emily Rauscher Thaddeus D. Komacek Jacob L. Bean Matej Malik Isaac Malsky Diagnosing Limb Asymmetries in Hot and Ultrahot Jupiters with High-resolution Transmission Spectroscopy The Astrophysical Journal Exoplanet atmospheric composition Radiative transfer simulations High resolution spectroscopy Hot Jupiters |
| title | Diagnosing Limb Asymmetries in Hot and Ultrahot Jupiters with High-resolution Transmission Spectroscopy |
| title_full | Diagnosing Limb Asymmetries in Hot and Ultrahot Jupiters with High-resolution Transmission Spectroscopy |
| title_fullStr | Diagnosing Limb Asymmetries in Hot and Ultrahot Jupiters with High-resolution Transmission Spectroscopy |
| title_full_unstemmed | Diagnosing Limb Asymmetries in Hot and Ultrahot Jupiters with High-resolution Transmission Spectroscopy |
| title_short | Diagnosing Limb Asymmetries in Hot and Ultrahot Jupiters with High-resolution Transmission Spectroscopy |
| title_sort | diagnosing limb asymmetries in hot and ultrahot jupiters with high resolution transmission spectroscopy |
| topic | Exoplanet atmospheric composition Radiative transfer simulations High resolution spectroscopy Hot Jupiters |
| url | https://doi.org/10.3847/1538-4357/acb141 |
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