JWST reveals the rapid and strong day-side variability of 55 Cancri e
Artikel i vetenskaplig tidskrift, 2024

Context. The nature of the close-in rocky planet 55 Cnce is puzzling, despite it having been observed extensively. Its optical and infrared occultation depths show temporal variability, in addition to a phase curve variability observed in the optical. Aims. We wish to explore the possibility that the variability originates from the planet being in a 3:2 spin- orbit resonance, and 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. Methods. JWST/NIRCam (Near Infrared Camera) observed five occultations (secondary eclipses) of the planet - of which four were observed within a week - 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. Results. 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 119-19+34 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 day-side temperature of bare rock with no heat redistribution (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. Conclusions. The observed variability could be explained by stochastic outgassing of CO/CO2, which is also hinted at 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.

Planets and satellites: atmospheres

Planets and satellites: terrestrial planets

Techniques: photometric

Planets and satellites: individual: 55 Cnc e

Techniques: spectroscopic

Författare

J. A. Patel

Stockholms universitet

A. Brandeker

Stockholms universitet

D. Kitzmann

Universität Bern

Dominique J.M. Petit dit de la Roche

Université de Genève

Aaron Bello-Arufe

California Institute of Technology (Caltech)

Kevin Heng

The University of Warwick

University College London (UCL)

Universität Bern

Ludwig-Maximilians-Universität München (LMU)

E. Meier Valdes

Universität Bern

Carina Persson

Chalmers, Rymd-, geo- och miljövetenskap, Astronomi och plasmafysik

Michael Zhang

University of Chicago

B.O. Demory

Universität Bern

V. Bourrier

Université de Genève

A. Deline

Université de Genève

D. Ehrenreich

Université de Genève

Malcolm Fridlund

Universiteit Leiden

Chalmers, Rymd-, geo- och miljövetenskap, Astronomi och plasmafysik

Renyu Hu

California Institute of Technology (Caltech)

M. Lendl

Université de Genève

A. V. Oza

California Institute of Technology (Caltech)

Y. Alibert

Universität Bern

M.J. Hooton

University of Cambridge

Astronomy and Astrophysics

0004-6361 (ISSN) 1432-0746 (eISSN)

Vol. 690 A159

Exoplaneter från rymden - CHEOPS och PLATO, ESA's nästa två rymdteleskop (fas 2)

Rymdstyrelsen (65/19), 2020-01-01 -- 2022-12-31.

Rymdstyrelsen (177/19), 2020-01-01 -- 2022-12-31.

Ämneskategorier

Rymd- och flygteknik

Astronomi, astrofysik och kosmologi

Sannolikhetsteori och statistik

DOI

10.1051/0004-6361/202450748

Relaterade dataset

URI: https://cdsarc.cds.unistra.fr/cgi-bin/qcat?J/ A+A/690/A159

Mer information

Senast uppdaterat

2024-11-05