# WASP-19 b: One Day in the Life of a Hot Jupiter **Independent research report by [Biswajit Jana](https://biswajit1999.github.io/Biswajit_Jana.github.io/)** · [Live report](https://biswajit1999.github.io/wasp-19b-exoplanet-report/) · [ORCID](https://orcid.org/0009-0002-2411-1891) · [Complete research portfolio](https://biswajit1999.github.io/Biswajit_Jana.github.io/research/exoplanets/)

Artist's interpretation of WASP-19 b near its host star

AI-generated artist's interpretation informed by the measured system properties; not a direct image.

**Ultra-short-period giant · stellar activity · TESS** A hot Jupiter completing an orbit in under a day, analyzed with timing freedom and explicit noise inflation in a regime where irradiation and stellar variability matter.

Phase-folded real TESS transit light curve of WASP-19 b

**[Open the full report](https://biswajit1999.github.io/wasp-19b-exoplanet-report/)** — the live GitHub Pages version. ## Data sources - **System parameters** — the saved `pscomppars` row from the [NASA Exoplanet Archive TAP service](https://exoplanetarchive.ipac.caltech.edu/TAP/sync?query=select+pl_name%2Chostname%2Cra%2Cdec%2Cpl_orbper%2Cpl_tranmid%2Cpl_trandur%2Cpl_rade%2Cpl_bmasse%2Cpl_eqt%2Cpl_orbsmax%2Csy_dist%2Csy_tmag%2Cst_teff%2Cst_rad%2Cst_mass%2Cdisc_year%2Cdiscoverymethod%2Cdisc_refname%2Cdisc_pubdate%2Cdisc_facility+from+pscomppars+where+pl_name%3D%27WASP-19+b%27&format=csv). - **Observed photometry** — unmodified MAST file `tess2019058134432-s0009-0000000035516889-0139-s_lc.fits`, TESS Sector 9, DOI [10.17909/t9-nmc8-f686](https://doi.org/10.17909/t9-nmc8-f686). This is a real SPOC reduced light curve, not simulated data. - Exact URLs, IDs, retrieval date, and SHA-256 checksum are in [`data/SOURCE.md`](data/SOURCE.md). ## Reproduce the analysis ```bash pip install -r requirements.txt python scripts/analyze_transit.py python scripts/analyze_multisector.py python scripts/analyze_timing_limits.py pytest tests/ -v ``` The script keeps finite `QUALITY == 0` cadences, normalizes `PDCSAP_FLUX`, and applies one symmetric robust outlier rule. A local linear null is compared with a circular quadratic-limb-darkened transit. The archive period and predicted phase are retained, while midpoint, radius ratio, impact parameter, baseline, and baseline slope are fitted inside a bounded window. The limb-darkening coefficients and scaled semi-major axis are fixed and disclosed in the CSV. ## What the corrected fit shows | Quantity | Result | |---|---:| | TESS sector | 9 | | Cadences in fitted window | 8212 | | Transit support | ΔBIC ≥ 10 | | Midpoint correction | +0.036 h ± 0.15 min | | Model mid-transit depth | 22844.2 ± 140.2 ppm | | Radius ratio Rp/Rs | 0.14738 | | Fitted / published duration | 1.648 / 1.607 h | | Linear null χ² / dof / BIC | 56047.03 / 8210 / 56065.05 | | Transit χ² / dof / BIC | 11554.80 / 8207 / 11599.87 | | ΔBIC (null − transit) | 44465.19 | The timing-adjusted transit is strongly preferred by ΔBIC = 44465.2. Its fitted midpoint is +0.036 hours from the historical prediction; the model's mid-transit depth is 22844.2 ± 140.2 ppm. A fitted timing correction can diagnose ephemeris drift, but this single-sector fit is not a replacement for a global transit-timing analysis. ## Multi-sector robustness and correlated noise The archive prediction was timing-adjusted independently in 3 fitted sector(s) (S9, S62, S63), of which 3 meet Delta BIC >= 10. Formal depth errors were inflated by sqrt(max(reduced chi-square, 1)) times the residual time-averaging beta factor (observed range 3.21-3.42). The robust inverse-variance model depth across supported sectors is 22782.8 +/- 265.1 ppm; Cochran Q = 0.12 for 2 dof (p = 0.9433). These scaled errors address underestimated scatter and short-timescale correlation, but they are not a full Gaussian-process or physical limb-darkened transit fit.

Independent sector transit fits for WASP-19 b

Sector depth consistency for WASP-19 b

Residual RMS time-averaging diagnostic for WASP-19 b

The per-sector table is in [`figures/multisector_statistics.csv`](figures/multisector_statistics.csv). Regenerate all three figures with `python scripts/analyze_multisector.py`. ## What can TESS alone say about orbital evolution?

TESS timing limits for WASP-19 b

This repository independently measures **89 transits** from TESS Sectors 9, 62, and 63 over 1,496 days. Each event uses a fixed sector-level transit shape while fitting its midpoint and local baseline. Its timing uncertainty is inflated by both a residual time-averaging factor and an empirical sector jitter of 34–47 seconds. The result is a useful negative sensitivity test: - a linear ephemeris is preferred over a quadratic one, with **Delta BIC(linear - quadratic) = -3.5**; - the conditional TESS-only estimate is **Pdot = -199 +/- 203 ms yr-1**; - the corresponding 95% negative bound is approximately **Pdot > -597 ms yr-1** under the stated Gaussian and equilibrium-tide assumptions; - that bound implies only **Q' star > 4.7 x 10^3**, far weaker than published long-baseline constraints. The large uncertainty is the scientific result: Sectors 62 and 63 are adjacent, leaving a long gap after Sector 9. A quadratic curve can bend almost unconstrained inside that gap, so the three-sector TESS sampling cannot test the few-ms-per-year regime discussed in the literature. The repository therefore does **not** claim a decay detection or a competitive tidal-quality limit. This conclusion also clarifies why longer baselines and alternative dynamical models matter. Petrucci et al. (2020) preferred a constant period over a ten-year baseline. Rajkumar et al. (2026), using a substantially enlarged 15-year dataset, found systematic non-linear timing structure better described by a cubic ephemeris and interpreted it as possible gradual apsidal precession rather than monotonic tidal decay. The TESS-only calculation here cannot distinguish those long-baseline scenarios. Machine-readable event timings are in [`figures/individual_transit_timings.csv`](figures/individual_transit_timings.csv), and the complete model comparison is in [`figures/timing_limit_statistics.csv`](figures/timing_limit_statistics.csv). ## System context - Radius: 15.86 Earth radii - Mass: 366.77 Earth masses - Orbital period: 0.788839 days - Transit duration: 1.607 hours - Semi-major axis: 0.0165 AU - Equilibrium temperature: 2113 K - Host: WASP-19 · distance 268.32 pc - Discovery: 2009 by Transit (SuperWASP) ## Limitations - The orbit is assumed circular and the quadratic limb-darkening coefficients are fixed representative values; they are not atmosphere-grid interpolations. - The scaled semi-major axis is derived from the saved composite semi-major axis and stellar radius; their uncertainties are not propagated. - Midpoint freedom corrects accumulated ephemeris error but introduces a bounded timing search. ΔBIC, not a naïve one-parameter p-value, is used as the support gate. - PDCSAP processing, dilution, stellar variability, transit-timing variations, and long-timescale covariance can still bias the inferred geometry. - Radius ratio, impact parameter, and fixed limb darkening are correlated. Published global fits with physical priors and simultaneous detrending remain authoritative. - Individual transit timings share sector-level detrending and stellar-activity systematics; adding a per-sector jitter reduces formal overconfidence but does not make the events fully independent. - The TESS sampling consists of one early sector and two adjacent late sectors. The reported Pdot interval is therefore conditional on a quadratic ephemeris and should not be used to reject apsidal precession or other secular models. ## Repository structure ```text README.md index.html requirements.txt data/ unmodified TESS FITS + NASA row + SOURCE.md scripts/analyze_transit.py timing-adjusted limb-darkened transit fit scripts/analyze_timing_limits.py individual transit timing + ephemeris limits figures/ generated plot + summary_statistics.csv tests/ real-data regression tests .github/workflows/tests.yml CI on every push and pull request LICENSE MIT ``` ## References 1. [Hebb et al. 2010](https://ui.adsabs.harvard.edu/abs/2010ApJ...708..224H/abstract) — discovery reference as listed by the NASA Exoplanet Archive. 2. Ricker, G. R. et al. (2015), *Transiting Exoplanet Survey Satellite (TESS)*, JATIS 1, 014003, [doi:10.1117/1.JATIS.1.1.014003](https://doi.org/10.1117/1.JATIS.1.1.014003). 3. TESS Team, *TESS Light Curves — All Sectors*, MAST, [doi:10.17909/t9-nmc8-f686](https://doi.org/10.17909/t9-nmc8-f686); Sector 9 used here. 4. [NASA Exoplanet Archive](https://exoplanetarchive.ipac.caltech.edu/), `pscomppars` TAP row retrieved 2026-08-15. 5. Petrucci, R. et al. (2020), *Discarding orbital decay in WASP-19b after one decade of transit observations*, [arXiv:1910.11930](https://arxiv.org/abs/1910.11930). 6. Rajkumar, A. R. et al. (2026), *Long-term monitoring of WASP-19 b: Signs of apsidal precession and molecular signatures*, [doi:10.1051/0004-6361/202556822](https://doi.org/10.1051/0004-6361/202556822). ## Author Biswajit Jana — [Portfolio](https://biswajit1999.github.io/Biswajit_Jana.github.io/) · [GitHub](https://github.com/Biswajit1999) · [LinkedIn](https://www.linkedin.com/in/biswajit-jana-27011a151/) · [ORCID](https://orcid.org/0009-0002-2411-1891)