Kavli Affiliate: Sara Seager
| First 5 Authors: , , , ,
| Summary:
The TRAPPIST-1 system offers one of the best opportunities to characterize
temperate terrestrial planets beyond our own solar system. Within the
TRAPPIST-1 system, planet e stands out as highly likely to sustain surface
liquid water if it possesses an atmosphere. Recently, we reported the first
JWST/NIRSpec PRISM transmission spectra of TRAPPIST-1 e, revealing significant
stellar contamination, which varied between the four visits. Here, we assess
the range of planetary atmospheres consistent with our transmission spectrum.
We explore a wide range of atmospheric scenarios via a hierarchy of forward
modeling and retrievals. We do not obtain strong evidence for or against an
atmosphere. Our results weakly disfavor CO$_2$-rich atmospheres for pressures
corresponding to the surface of Venus and Mars and the cloud tops of Venus at
2$sigma$. We exclude H$_2$-rich atmospheres containing CO$_2$ and CH$_4$ in
agreement with past work, but find that higher mean molecular weight,
N$_2$-rich atmospheres with trace CO$_2$ and CH$_4$ are permitted by the data.
Both a bare rock and N$_2$-rich atmospheric scenario provide adequate fits to
the data, but do not fully explain all features, which may be due to either
uncorrected stellar contamination or atmospheric signals. Ongoing JWST
observations of TRAPPIST-1 e, exploiting consecutive transits with TRAPPIST-1
b, will offer stronger constraints via a more effective stellar contamination
correction. The present work is part of the JWST Telescope Scientist Team
(JWST-TST) Guaranteed Time Observations, which is performing a Deep
Reconnaissance of Exoplanet Atmospheres through Multi-instrument Spectroscopy
(DREAMS).
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