Strict Limits on Potential Secondary Atmospheres on the Temperate Rocky Exo-Earth TRAPPIST-1 d

Piaulet-Ghorayeb, C; Benneke, B; Turbet, M; Moore, K; Roy, P; Lim, O; Doyon, R; Fauchez, TJ; Albert, L; Radica, M; Coulombe, L; Lafrenière, D; Cowan, NB; Belzile, D; Musfirat, K; Kaur, M; L’Heureux, A; Johnstone, D; MacDonald, RJ; Allart, R; Dang, L; Kaltenegger, L; Pelletier, S; Rowe, JF; Taylor, J

Journal article

Strict Limits on Potential Secondary Atmospheres on the Temperate Rocky Exo-Earth TRAPPIST-1 d

Abstract:: The nearby TRAPPIST-1 system, with its seven small rocky planets orbiting a late-type M8 star, offers an unprecedented opportunity to search for secondary atmospheres on temperate terrestrial worlds. In particular, the 0.8 R⊕TRAPPIST-1 d lies at the edge of the habitable zone (Teq,A=0.3 = 262 K). Here we present the first 0.6–5.2 μm NIRSpec/PRISM transmission spectrum of TRAPPIST-1 d from two transits with JWST. We find that stellar contamination from unocculted bright heterogeneities introduces 500–1000 ppm visit-dependent slopes, consistent with constraints from the out-of-transit stellar spectrum. Once corrected, the transmission spectrum is flat within ±100–150 ppm, showing no evidence for a haze-like slope or molecular absorption despite NIRSpec/PRISM’s sensitivity to CH4, H2O, CO, SO2, and CO2. Our observations exclude clear, hydrogen-dominated atmospheres with high confidence (>3σ). We leverage our constraints on even trace amounts of CH4, H2O, and CO2 to further reject high mean molecular weight compositions analogous to a haze-free Titan, a cloud-free Venus, early Mars, and both Archean Earth and a cloud-free modern Earth scenario (>95% confidence). If TRAPPIST-1 d retains an atmosphere, it is likely extremely thin or contains high-altitude aerosols, with water cloud formation at the terminator predicted by 3D global climate models. Alternatively, if TRAPPIST-1 d is airless, our evolutionary models indicate that TRAPPIST-1 b, c, and d must have formed with ≲4 Earth oceans of water, though this would not preclude atmospheres on the cooler habitable-zone planets TRAPPIST-1 e, f, and g.

Publication status:: Published

Peer review status:: Peer reviewed

Actions

Email

Email this record

Send the bibliographic details of this record to your email address.

Your Email
Please enter the email address that the record information will be sent to.

-
Your message (optional)
Please add any additional information to be included within the email.
Cite

Cite this record

APA Style

Piaulet-Ghorayeb, C., Benneke, B., Turbet, M., Moore, K., Roy, P., Lim, O., Doyon, R., Fauchez, T. J., Albert, L., Radica, M., Coulombe, L., Lafrenière, D., Cowan, N. B., Belzile, D., Musfirat, K., Kaur, M., L’Heureux, A., Johnstone, D., MacDonald, R. J., … Taylor, J. (2025). Strict Limits on Potential Secondary Atmospheres on the Temperate Rocky Exo-Earth TRAPPIST-1 d. The Astrophysical Journal, 989(2).

MLA Style

Piaulet-Ghorayeb, C., et al. “Strict Limits on Potential Secondary Atmospheres on the Temperate Rocky Exo-Earth TRAPPIST-1 d.” The Astrophysical Journal, vol. 989, no. 2, American Astronomical Society, 2025.

Chicago Style

Piaulet-Ghorayeb, C, B Benneke, M Turbet, K Moore, P Roy, O Lim, R Doyon, et al. 2025. “Strict Limits on Potential Secondary Atmospheres on the Temperate Rocky Exo-Earth TRAPPIST-1 d.” The Astrophysical Journal 989 (2).
Share
Print