Are habitable-zone TESS Objects of Interest really there? Period resolution from the full archive

Abstract

TESS Objects of Interest (TOIs) seen as single or duo transits carry a catalogue period that is undefined or equal to the separation of the two events, and their insolation and any habitable-zone label inherit it. We reanalyse all 187 TOIs catalogued with P = 0 or P >= 200 d using all public TESS data through Sector 107, with a flux-based method that weights each alias by per-epoch transit likelihoods, the transit duration and a geometric prior, and tests for coherence, data edges, contamination by other planets and instrumental artefacts. It recovers 12 published periods blindly and, in injection-recovery tests, 71 per cent of periods constrained by a new transit, with no wrong period. It resolves 28 periods and fixes 8 more by exclusion. Are habitable-zone TOIs really there? Mostly not: of the 28 duo-transits that a catalogue-period criterion places in the conservative habitable zone, about two are expected to lie there, both giants, and none of the 12 planet-sized ones; those resolved are aliases of hotter planets. Conversely, habitable-zone planets hide behind missing or wrong periods: we recover three published M-dwarf examples and validate four planets with new periods, including TOI-2298 b, a 3.0 Earth-radius sub-Neptune at 146.58 d in the conservative habitable zone of a K dwarf, and TOI-6075 b, a 1.7 Earth-radius planet at 416.5 d (833 d not excluded), the second validated transiting planet smaller than 2 Earth radii with P > 1 yr. We release alias-marginalised habitable-zone probabilities for the whole sample.