What the corrected fit shows
The timing-adjusted transit is strongly preferred by ΔBIC = 7853.6. Its fitted midpoint is +0.065 hours from the historical prediction; the model's mid-transit depth is 6972.3 ± 81.0 ppm. The support decision uses ΔBIC ≥ 10; timing-search p-values are not presented as blind-detection probabilities.
Explicit model comparison
BIC = 10076.46
BIC = 2222.89
The null fits a local intercept and slope. The transit adds bounded midpoint, radius-ratio, and impact-parameter freedom while retaining the same baseline terms. Fixed limb darkening and circular geometry make this a diagnostic fit rather than a full system retrieval.
Multi-sector robustness and noise
The archive prediction was timing-adjusted independently in Sectors 44, 45, 46, 71, and 72; all five meet ΔBIC ≥ 10. Formal depth errors were inflated by sqrt(max(reduced χ², 1)) and the residual time-averaging beta factor. The inverse-variance depth is 6910.9 ± 50.3 ppm, and the five-sector Q diagnostic finds no excess depth dispersion (Q = 1.97 for 4 dof; p = 0.740). These scaled errors address underestimated scatter and short-timescale correlation, but they are not a full Gaussian-process or global physical transit fit.
Atmospheric evidence: detection, limit, or unknown?
Evidence scope — citation only; no spectrum bundled. The molecular table and evidence graphic summarize the cited retrieval. This repository does not contain or reanalyze a reduced planetary spectrum.
The cited joint JWST, Hubble, and Spitzer retrieval reports four molecules above 3 sigma and interprets SO2 as disequilibrium photochemistry. This repository audits those published claims but does not re-run the atmospheric retrieval because its reduced spectrum is not bundled here.
| Species | Status | Evidence | Basis |
|---|---|---|---|
| SO2 | reported detection | >3 sigma | joint atmospheric retrieval |
| H2O | reported detection | >3 sigma | joint atmospheric retrieval |
| CO2 | reported detection | >3 sigma | joint atmospheric retrieval |
| CH4 | reported detection | >3 sigma; underabundant | joint retrieval versus equilibrium expectation |
| O2 | no evidence | not reported | oxygen-bearing molecules do not imply molecular oxygen |
Primary source: Beatty et al. 2024, ApJL. Oxygen-bearing molecules are not detections of molecular oxygen (O2) and are not, by themselves, biosignatures.
The system
| Radius | 4.57 Earth radii |
|---|---|
| Mass | 13.90 Earth masses |
| Orbital period | 3.336650 days |
| Transit duration | 1.898 hours |
| Semi-major axis | 0.0355 AU |
| Equilibrium temperature | 594 K |
| Host and distance | GJ 3470 · 29.42 pc |
| Discovery | 2012 · Radial Velocity · La Silla Observatory |
Values are from the exact saved NASA Exoplanet Archive pscomppars row in data/system_parameters.csv.
Data and reproducibility
The observed photometry comprises five public MAST SPOC 2-minute files from TESS Sectors 44, 45, 46, 71, and 72, collection DOI 10.17909/t9-nmc8-f686. They are stored unmodified. Exact archive URI, URL, retrieval date, and checksum are in data/SOURCE.md.
Run python scripts/analyze_transit.py and python scripts/analyze_multisector.py and python scripts/analyze_atmospheric_evidence.py to regenerate the figures and CSVs, then pytest tests/ -v to check the documented values against the real file.
Limitations
- The orbit is circular and the quadratic limb-darkening coefficients are fixed representative values.
- The scaled semi-major axis comes from saved composite values whose uncertainties are not propagated.
- The midpoint is searched within a bounded window; ΔBIC is used as the support gate.
- PDCSAP processing, dilution, stellar variability, timing variations, and covariance can bias the geometry.
- Published global fits with physical priors, instrument-specific detrending, and simultaneous sectors remain authoritative.
References
- Bonfils et al. 2012 — discovery reference listed by the NASA Exoplanet Archive.
- Ricker et al. (2015), Transiting Exoplanet Survey Satellite (TESS), doi:10.1117/1.JATIS.1.1.014003.
- TESS Team, TESS Light Curves — All Sectors, MAST, doi:10.17909/t9-nmc8-f686; Sectors 44, 45, 46, 71, and 72 used here.
- NASA Exoplanet Archive, saved TAP row retrieved 2026-08-15.