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astro-ph.EP · Earth and Planetary Astrophysicsastro-ph.SR · Solar and Stellar Astrophysics

Fitting stellar signals reduces the apparent 2019 to 2024 TESS half-depth transit width decrease of WASP-33 b from 2.90 to 0.62 minutes

WASP-33 b crosses a star with strong pulsations. We test if its transit width changed in TESS Sectors 18, 58, and 85, observed in 2019, 2022, and 2024. We fit a free smooth transit profile, 36 fixed stellar frequencies with free coefficients in each visit, and slow flux trends. We define width by the two crossings at half the mean central flux loss. The fitted widths are 149.82, 149.55, and 149.19 minutes. The 2024 minus 2019 difference is -0.62 minutes. Its 95% interval is [-1.75, 0.47] minutes for noise blocks of one orbit and [-1.38, 0.16] minutes for blocks of two orbits. These fits do not establish a width change. A fit that omits the stellar signals gives a larger apparent decrease of 2.90 minutes. Changes to the flux product, slow trends, profile spacing, and stellar signal list give differences from -0.75 to -0.62 minutes when stellar signals are included. Artificial transits test the effect of the profile fit and observed noise. This empirical width is not the contact duration. The intervals depend on the fixed frequency list and on independent noise blocks. We release the input light curves, source code, results, figures, and data records.

WASP-33 b · TESS · transit width · stellar pulsations · nodal precession · reproducible photometry · injection recovery

Admitted 1 citing publication

References

7
  1. usesThe WASP-33 signal at 27.795 cycles per day was weaker in the 2024 TESS data than in 2022 sci:sha256:685f58fe9cad1fd1063ec670ebce4fe81726b25992d78487f7a5013c326de7ff

    We use its input product records and numerical stellar period table, and adapt its quality selection and slow trend design. We download the FITS data again from MAST and verify the same hashes.

  2. usesdoi:10.1093/mnras/staf011

    The published stellar periods and transit ephemeris define the fixed signal basis and reference transit times.

  3. usesdoi:10.17909/t9-nmc8-f686

    The NASA TESS data collection at MAST supplies the three SPOC two minute light curves.

  4. doi:10.1093/mnras/stac620

    Prior spectra and photometry establish nodal precession of WASP-33 b. We do not claim a new detection of precession.

  5. doi:10.1051/0004-6361/202452151

    Prior CHEOPS transit fits support precession and show that the fitted contact duration depends on the stellar surface brightness model.

  6. doi:10.48550/arXiv.2203.02546

    This prior study models precession in WASP-33 b and KELT-9 b.

  7. usesdoi:10.3847/1538-4357/ac7c74

    Astropy reads the preserved FITS light curves.

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