TIC 88338227: 10 TESS eclipses and 3 SuperWASP eclipses from 2007 give P = 12.43746 d; Gaia DR3 density and RV range show that the 1.4 % eclipse is probably not from a companion of the F star

TIC 88338227 (TYC 6440-73-1, Tmag 10.57) is an F star with Gaia DR3 FLAME mass 1.24 Msun, radius 1.57 Rsun and mean density 0.32 solar. The SCI publication sci:sha256:58e512dfb29aef9ce3a0320ce7332b1e53947e8c79ee036d1626e9b6a418b9d1 first reported a 1.4 % V-shaped eclipse of this star from 4 TESS eclipses and called it an eclipsing binary or blend candidate. This follow-up adds these results. (1) We measured 10 TESS eclipses (SPOC 2-min data, sectors 105-107; our own full-frame-image photometry, sectors 97 and 108). The linear ephemeris is P = 12.437499 +- 0.000014 d over 373 d. The depths agree, the odd and even depths agree (0.3 sigma), there is no secondary eclipse (-105 +- 71 ppm), and the DV centroid offset is 0.3 +- 2.5 arcsec. No Gaia DR3 source within 60 arcsec is bright enough to make the eclipse. (2) The eclipse lasts 2.34 h. For a circular orbit around a star with the Gaia density, the best transit model is worse than the free fit by -2 dlnL = 979. A companion of the F star needs e >= 0.28-0.37. (3) The Gaia DR3 RV range (8.44 km/s, 12 visibility periods) limits a 12.44 d companion of the F star to M2 < 0.07 Msun (95 %, e = 0-0.8, sin i = 1, omega = 90 deg, Monte Carlo with random phases). The TESS fit needs a radius ratio k >= 0.126, thus a body larger than about 0.19 Rsun. A body below 0.07 Msun is too small, and an M dwarf of this size is too massive. Thus the eclipsing pair is probably not the F star and a companion. It is probably a blend that Gaia does not resolve or a hierarchical triple (Gaia RUWE 5.1). (4) Three partial eclipses in SuperWASP data from November-December 2007 occur 32 +- 3 min after the TESS-only prediction (prediction error 10.8 min; 2.9 sigma). Four baseline models give the same result. The same method on WASP-72 b and WASP-22 b gives offsets that agree with zero. Possible causes are a light-travel-time effect, a period change or noise. The joint TESS + SuperWASP ephemeris is P = 12.43745957 +- 0.0000036 d over 18.8 yr. (5) We give 63 predicted eclipse times for November 2026 to December 2028. (6) The package also contains the full output of our single-event search of 12,998 TESS sector 107 light curves, in which this eclipse was found. The package contains the code, the TESS input data, all derived results, and scripts that download the third-party data.

TIC 88338227 · TYC 6440-73-1 · eclipsing binary · blend · hierarchical triple · TESS · SuperWASP · Gaia DR3 · radial velocity · RUWE · stellar density · transit duration · eclipse timing · light-travel-time effect · ephemeris · predicted eclipse times · single transit search · false positive