JWST reveals a rapid and strong day side variability of 55 Cancri e
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arXiv
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| Natura: | Preprint |
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2024
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| author | Patel, J. A. Brandeker, A. Kitzmann, D. de la Roche, D. J. M. Petit dit Bello-Arufe, A. Heng, K. Valdés, E. Meier Persson, C. M. Zhang, M. Demory, B. -O. Bourrier, V. Deline, A. Ehrenreich, D. Fridlund, M. Hu, R. Lendl, M. Oza, A. V. Alibert, Y. Hooton, M. J. |
| author_facet | Patel, J. A. Brandeker, A. Kitzmann, D. de la Roche, D. J. M. Petit dit Bello-Arufe, A. Heng, K. Valdés, E. Meier Persson, C. M. Zhang, M. Demory, B. -O. Bourrier, V. Deline, A. Ehrenreich, D. Fridlund, M. Hu, R. Lendl, M. Oza, A. V. Alibert, Y. Hooton, M. J. |
| contents | The nature of the close-in rocky planet 55 Cnc e is puzzling despite having been observed extensively. Its optical and infrared occultation depths show temporal variability, in addition to a phase curve variability observed in the optical. We wish to explore the possibility that the variability originates from the planet being in a 3:2 spin-orbit resonance, thus showing different sides during occultations. We proposed and were awarded Cycle 1 time at the James Webb Space Telescope (JWST) to test this hypothesis. JWST/NIRCam observed five occultations (secondary eclipses), of which four were observed within a week, of the planet simultaneously at 2.1 and 4.5 μm. While the former gives band-integrated photometry, the latter provides a spectrum between 3.9-5.0 μm. We find that the occultation depths in both bandpasses are highly variable and change between a non-detection (-5 +/- 6 ppm and 7 +/- 9 ppm) to 96 +/- 8 ppm and 119 (+34) (-19) ppm at 2.1 μm and 4.5 μm, respectively. Interestingly, the variations in both bandpasses are not correlated and do not support the 3:2 spin-orbit resonance explanation. The measured brightness temperature at 4.5 μm varies between 873-2256 K and is lower than the expected dayside temperature of bare rock with no heat re-distribution (2500 K) which is indicative of an atmosphere. Our atmospheric retrieval analysis of occultation depth spectra at 4.5 μm finds that different visits statistically favour various atmospheric scenarios including a thin outgassed CO/CO2 atmosphere and a silicate rock vapour atmosphere. Some visits even support a flat line model. The observed variability could be explained by stochastic outgassing of CO/CO2, which is also hinted by retrievals. Alternatively, the variability, observed at both 2.1 and 4.5 μm, could be the result of a circumstellar patchy dust torus generated by volcanism on the planet. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2407_12898 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | JWST reveals a rapid and strong day side variability of 55 Cancri e Patel, J. A. Brandeker, A. Kitzmann, D. de la Roche, D. J. M. Petit dit Bello-Arufe, A. Heng, K. Valdés, E. Meier Persson, C. M. Zhang, M. Demory, B. -O. Bourrier, V. Deline, A. Ehrenreich, D. Fridlund, M. Hu, R. Lendl, M. Oza, A. V. Alibert, Y. Hooton, M. J. Earth and Planetary Astrophysics The nature of the close-in rocky planet 55 Cnc e is puzzling despite having been observed extensively. Its optical and infrared occultation depths show temporal variability, in addition to a phase curve variability observed in the optical. We wish to explore the possibility that the variability originates from the planet being in a 3:2 spin-orbit resonance, thus showing different sides during occultations. We proposed and were awarded Cycle 1 time at the James Webb Space Telescope (JWST) to test this hypothesis. JWST/NIRCam observed five occultations (secondary eclipses), of which four were observed within a week, of the planet simultaneously at 2.1 and 4.5 μm. While the former gives band-integrated photometry, the latter provides a spectrum between 3.9-5.0 μm. We find that the occultation depths in both bandpasses are highly variable and change between a non-detection (-5 +/- 6 ppm and 7 +/- 9 ppm) to 96 +/- 8 ppm and 119 (+34) (-19) ppm at 2.1 μm and 4.5 μm, respectively. Interestingly, the variations in both bandpasses are not correlated and do not support the 3:2 spin-orbit resonance explanation. The measured brightness temperature at 4.5 μm varies between 873-2256 K and is lower than the expected dayside temperature of bare rock with no heat re-distribution (2500 K) which is indicative of an atmosphere. Our atmospheric retrieval analysis of occultation depth spectra at 4.5 μm finds that different visits statistically favour various atmospheric scenarios including a thin outgassed CO/CO2 atmosphere and a silicate rock vapour atmosphere. Some visits even support a flat line model. The observed variability could be explained by stochastic outgassing of CO/CO2, which is also hinted by retrievals. Alternatively, the variability, observed at both 2.1 and 4.5 μm, could be the result of a circumstellar patchy dust torus generated by volcanism on the planet. |
| title | JWST reveals a rapid and strong day side variability of 55 Cancri e |
| topic | Earth and Planetary Astrophysics |
| url | https://arxiv.org/abs/2407.12898 |