TIC 50099421.01: a 2.2 Earth-radius planet candidate on a 5.54-day orbit around a nearby K dwarf, found in TESS full-frame images
Year: 2026
Type: preprint
Abstract: We report a transiting planet candidate around TIC 50099421 (Gaia DR3 3028405599610871680), a T = 10.8 K dwarf at 67.3 pc, found by Tessa, an open search of TESS full-frame-image light curves of nearby K and M dwarfs that were mostly never observed at 2-minute cadence. Data from 4 sectors show 17 transits with period P = 5.537492 ± 0.000014 d, depth 889 ppm and duration 2.60 h (SNR 15.1), implying a planet radius of 2.22+0.20−0.10 R⊕. The signal passes these tests: odd and even transits agree (2.1σ) and there is no significant secondary eclipse (SNR 2.6); the depth is consistent across sectors (p = 0.29); the stellar density implied by the transit shape matches the catalogue value (ratio 1.40, 68% interval 0.39–1.86); difference imaging places the source on the target (4.0″ ± 2.4″, 3 sectors) and on none of the 78 Gaia neighbours bright enough to fake it; Gaia DR3 astrometry (RUWE 1.06) and radial velocities show no sign that the target is a binary; in a leave-one-season-out test, each of 4 seasons is predicted from the others and shows the dip at the predicted times; the identical search on this star's upside-down light curve finds nothing stronger than SNR 6.8, against 15.1 for the dip. TRICERATOPS gives FPP = 0.052, but NFPP = 2.0e-03 is above the 0.001 that the "likely planet" class also requires (Giacalone et al. 2021): by that test a nearby star is not yet excluded as the source. The candidate matches no known planet, TOI, CTOI, catalogued eclipsing binary or variable star. Other searches have also reported it (RAVEN (Zenodo 19661443); Ibrahim 2026 (doi 10.5281/zenodo.23569126)); Tessa found it independently, and this note adds its own vetting and predictions. We give an ephemeris and predicted transit times (timing uncertainty ≈8 min) for TESS Sector 110, which observes the star from 2026-10-30 to 2026-11-26, and for ground-based observations, and set out in advance the criterion by which new data will test the prediction. Files: the preprint (PDF); every predicted transit to 2027-06-30, with ground-site observability (CSV); and the candidate parameters (JSON).
Author: Barve, Rushikesh
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7225261737