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

TESS 2-min light curves (2019-2026) show transit-duration trends in 6 of 120 planets around hot stars and 1 of 271 around cooler stars; WASP-167 b is a new nodal-precession candidate

Question: Do secular changes of transit duration (T14), which nodal precession around fast-rotating oblate stars causes, occur preferentially around hot stars in a uniform TESS sample? Does TESS show new precessing planets? Approach: We fit TESS SPOC 2-min PDCSAP light curves from sectors 1-107 (2018-2026, 2,620 files) for 419 confirmed planets with P < 10 d, depth >= 0.3 %, Tmag <= 12.5 and data in at least two seasons over at least 1.5 yr. In each season we fit a batman model: a/R* and limb darkening were shared, and Rp/R*, impact parameter and time offset were free. Each transit had its own linear baseline, delta-Scuti pulsations were prewhitened, and errors came from a bootstrap over transits. We calibrated the error scale on 134 cool hosts (Teff <= 5700 K). Results: 6 of 120 hot-host planets (Teff >= 6250 K) have T14 trends above 3 sigma, against 1 of 271 cooler-host planets (one-sided Fisher p = 0.004). Four of the five planets with published precession pass 3 sigma, and WASP-33 b has z = -3.0. For TOI-1518 b, the published rate predicts the 2024 durations out of sample (chi2 0.1 against 70.7 for no change). Our db/dt = -0.0119 +- 0.0009 /yr agrees with the published -0.0116 +- 0.0036 /yr. The KELT-9 b decrease agrees with the Doppler-tomography rate (chi2 4.4 for 3 dof, against 108.7 for no change). WASP-167 b, a retrograde planet of a rapidly rotating F1V star, is a new candidate: T14 increases monotonically from 176.7 to 181.9 min between 2019 and 2026 (+0.70 +- 0.10 min/yr, z = 6.7 over four seasons; z = 7.3 to 8.9 in other variants), so db/dt is approximately -0.0033 /yr. HAT-P-70 b, a near-polar planet of an A star, shows a weaker trend (z = 3.4 over two seasons). For 88 other hot-host planets with b > 0.3, the median 3-sigma limit on |db/dt| is 0.0057 /yr. Limitations: All results come from TESS alone. The model does not include gravity darkening or eccentricity, so absolute b values for fast rotators are biased. Many planets have only two seasons. Without the five known precessors, the population excess is not significant (2/115 against 1/271, p = 0.21).

TESS · transit duration variation · nodal precession · hot Jupiters · stellar oblateness · spin-orbit misalignment · WASP-167 b · HAT-P-70 b · TOI-1518 b · KELT-9 b · TOI-1355 b · Kepler-13A b · WASP-33 b · Kraft break · out-of-sample test

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References

12
  1. usesTESS data show transits at the radial-velocity period of TOI-1117 c and exclude most transits of 423 other radial-velocity planets with periods up to 100 days sci:sha256:f0ef9edd19928a25a0cae794dccde12416fe7c02c90b3f82d2460251d2cb1c11

    We reuse its NASA Exoplanet Archive pscomppars transiting-planet snapshot (2026-11-08) for sample selection, because the archive was unavailable on 2026-11-09.

  2. TESS transits after January 2023 support published period changes for WASP-12 b and HAT-P-7 b and reject them for 7 of 24 tested hot-Jupiter candidates sci:sha256:dd04348fcad9296dd08f6abe0d55984cd9d4986d758fafe8712b2d775be0876d

    Related campaign TESS 2-min hot-Jupiter timing study (period changes). This work measures durations instead.

  3. TESS transit times from 2018 to 2026 agree with reported period changes of WASP-12 b and HAT-P-7 b, do not agree with 9 of 23 other reported changes, and show a curved KELT-20 b ephemeris sci:sha256:8ecb9990f7282ea1040f88b29800ee2ac4145360aef34a844b14e4db662c8fc2

    Related campaign TESS transit-timing study.

  4. uses, supportsdoi:10.3847/1538-4357/ac6b9a

    Stephan et al. 2022: WASP-33 b and KELT-9 b precession rates used as controls. Our TESS T14 decline of KELT-9 b supports a growing impact parameter (the Table 1 sign).

  5. uses, supportshttps://arxiv.org/abs/2402.17325

    Watanabe et al. 2024 (PASJ 76, 374): TOI-1518 b db/dt from 2019 and 2022 data. Our 2024 TESS durations agree out of sample.

  6. useshttps://arxiv.org/abs/1911.11399

    Szabo et al. 2020: Kepler-13A b db/dt used as a control.

  7. useshttps://arxiv.org/abs/2608.17387

    TOI-1355 b discovery paper (PASJ 2026): db/dt from the same TESS sectors, used as an in-sample control.

  8. https://arxiv.org/abs/1704.07771

    Temple et al. 2017: discovery of WASP-167 b/KELT-13 b, with a retrograde orbit (lambda = -165 deg) around a rapidly rotating pulsating F1V star.

  9. https://arxiv.org/abs/2112.03292

    Bello-Arufe et al. 2022: HAT-P-70 b near-polar orbit and v sin i.

  10. useshttps://archive.stsci.edu/tess/

    TESS SPOC 2-min light curves, sectors 1-107.

  11. usesdoi:10.26133/NEA12

    NASA Exoplanet Archive Planetary Systems Composite Parameters.

  12. doi:10.1086/683602

    batman transit model (Kreidberg 2015).

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