Breakthrough Tracker record
K2-18 b DMS/DMDS molecular and biosignature claim
A 2025 JWST analysis reported about 3σ evidence for dimethyl sulfide and/or dimethyl disulfide in K2-18 b's atmosphere. Independent reductions found the MIRI result sensitive to binning and instrumental systematics and did not recover statistically significant DMS/DMDS evidence.
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- Stable ID
k2-18b-dms-dmds-2025- Revision
k2-18b-dms-dmds-2025.v1- Field
- Astronomy · Exoplanet atmospheres and astrobiology
- Evidence
- Tier 1 · Peer reviewed: Yes
- Record state
- Disputed · Disputed; insufficient evidence
- Last checked
AI role
No AI assistance was disclosed as a contributor to the linked spectral-retrieval studies.
Record details
- Problem or result
- Whether JWST spectra establish dimethyl sulfide or dimethyl disulfide in K2-18 b's atmosphere
- Authors
- Nikku Madhusudhan and collaborators; independent reanalyses by Rafael Luque and collaborators
- Institutions
- University of Cambridge and independent JWST-analysis teams
- Result date
- Original analysis April 16, 2025; independent reanalyses from May 2025
Why it matters
A well-verified atmospheric biosignature on a temperate exoplanet would be a landmark result, which makes strict molecular and instrumental verification essential.
Limits
The molecules were degenerate, the significance was below the usual discovery threshold and plausible atmospheric or instrumental alternatives remain. Required wording: tentative and disputed molecular retrieval; not a biosignature detection and not evidence that life has been found.
Sources
- Primary: Original DMS/DMDS analysis
- Primary: Independent reanalysis finding insufficient evidence
- Primary: Final Astrophysical Journal Letters paper for the original claim
- Primary: Final Astronomy & Astrophysics version of the reanalysis
- Independent: Subsequent peer-reviewed systematic analysis in The Astronomical Journal
Correction and revision history
- July 22, 2026 — Rechecked the original claim, independent reanalysis and systematic study. Added final journal links where available; the disputed/insufficient-evidence status is unchanged.
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