Characterising the Atmosphere of 55 Cancri e: 1D Forward Model Grid for Current and Future JWST Observations

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Hauptverfasser: Zilinskas, Mantas, van Buchem, Christiaan, Zieba, Sebastian, Miguel, Yamila, Sandford, Emily, Hu, Renyu, Patel, Jayshil, Bello-Arufe, Aaron, Janssen, Leoni, Tsai, Shang-Min, Dragomir, Diana, Zhang, Michael
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Veröffentlicht: 2025
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author Zilinskas, Mantas
van Buchem, Christiaan
Zieba, Sebastian
Miguel, Yamila
Sandford, Emily
Hu, Renyu
Patel, Jayshil
Bello-Arufe, Aaron
Janssen, Leoni
Tsai, Shang-Min
Dragomir, Diana
Zhang, Michael
author_facet Zilinskas, Mantas
van Buchem, Christiaan
Zieba, Sebastian
Miguel, Yamila
Sandford, Emily
Hu, Renyu
Patel, Jayshil
Bello-Arufe, Aaron
Janssen, Leoni
Tsai, Shang-Min
Dragomir, Diana
Zhang, Michael
contents Recent JWST observations with NIRCam and MIRI of the ultra-short-period super-Earth 55 Cancri e indicate a possible volatile atmosphere surrounding the planet. Previous analysis of the NIRCam spectra suggested potential absorption features from CO2 or CO and significant sub-weekly variability. The MIRI low-resolution spectrum does not contain substantial features but was found to be consistent with effective heat redistribution models. In this work, we computed a grid of over 25000 self-consistent 1D forward models incorporating H-N-O-C-S-P-Si-Ti equilibrium chemistry and assessed plausible atmospheric compositions based on the current JWST data. Despite exhaustive analysis, the composition and properties of the atmosphere remain elusive. While our results statistically favour a global, hydrogen-free, nitrogen-dominated atmosphere enriched in PO and CO2, various alternative compositions, including H2O-,CO-, PH3-, or Si-bearing remain viable explanations. Unconstrained heat redistribution efficiency and absolute NIRCam flux are among the largest sources of uncertainty in our analysis. We also find that the heat redistribution factor and surface pressure are highly degenerate with atmospheric composition, and that these parameters cannot be independently constrained using current JWST observations. Furthermore, we show that the observed variability may arise from dynamic interactions between the atmosphere and an underlying magma ocean, driving rapid shifts in atmospheric chemistry and thermal emission. Our results highlight the importance of using self-consistent forward models when analysing novel JWST spectra with limited signal-to-noise ratios -- such as those of 55 Cancri e -- as it allows for a more comprehensive evaluation of potential atmospheric scenarios while also being less sensitive to subtle spectral differences than retrievals...
format Preprint
id arxiv_https___arxiv_org_abs_2503_15844
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Characterising the Atmosphere of 55 Cancri e: 1D Forward Model Grid for Current and Future JWST Observations
Zilinskas, Mantas
van Buchem, Christiaan
Zieba, Sebastian
Miguel, Yamila
Sandford, Emily
Hu, Renyu
Patel, Jayshil
Bello-Arufe, Aaron
Janssen, Leoni
Tsai, Shang-Min
Dragomir, Diana
Zhang, Michael
Earth and Planetary Astrophysics
Instrumentation and Methods for Astrophysics
Recent JWST observations with NIRCam and MIRI of the ultra-short-period super-Earth 55 Cancri e indicate a possible volatile atmosphere surrounding the planet. Previous analysis of the NIRCam spectra suggested potential absorption features from CO2 or CO and significant sub-weekly variability. The MIRI low-resolution spectrum does not contain substantial features but was found to be consistent with effective heat redistribution models. In this work, we computed a grid of over 25000 self-consistent 1D forward models incorporating H-N-O-C-S-P-Si-Ti equilibrium chemistry and assessed plausible atmospheric compositions based on the current JWST data. Despite exhaustive analysis, the composition and properties of the atmosphere remain elusive. While our results statistically favour a global, hydrogen-free, nitrogen-dominated atmosphere enriched in PO and CO2, various alternative compositions, including H2O-,CO-, PH3-, or Si-bearing remain viable explanations. Unconstrained heat redistribution efficiency and absolute NIRCam flux are among the largest sources of uncertainty in our analysis. We also find that the heat redistribution factor and surface pressure are highly degenerate with atmospheric composition, and that these parameters cannot be independently constrained using current JWST observations. Furthermore, we show that the observed variability may arise from dynamic interactions between the atmosphere and an underlying magma ocean, driving rapid shifts in atmospheric chemistry and thermal emission. Our results highlight the importance of using self-consistent forward models when analysing novel JWST spectra with limited signal-to-noise ratios -- such as those of 55 Cancri e -- as it allows for a more comprehensive evaluation of potential atmospheric scenarios while also being less sensitive to subtle spectral differences than retrievals...
title Characterising the Atmosphere of 55 Cancri e: 1D Forward Model Grid for Current and Future JWST Observations
topic Earth and Planetary Astrophysics
Instrumentation and Methods for Astrophysics
url https://arxiv.org/abs/2503.15844