Identify the host star of TOI 3353.01

Determine which component of the unresolved binary system TOI 3353.01 hosts the transiting exoplanet, in order to establish the planet’s dilution-corrected radius and the corresponding TESS detection sensitivity.

Background

The paper emphasizes that dilution by an unresolved stellar companion can substantially alter the inferred planetary radius. For TOI 3353.01, the host star is not yet identified, so the authors calculate separate sensitivity curves under the assumptions that the planet orbits either the primary or the secondary. These alternatives produce markedly different detectability limits: TESS could detect Earth-sized short-period planets around the primary, whereas it would be sensitive mainly to planets larger than approximately 4 Earth radii around the secondary.

References

Sensitivity curves for an illustrative binary TOI in our sample in which it is currently unknown which of the binary stars is the host of the transiting exoplanet TOI 3353.01.

— The sensitivity of TESS to transiting planets in TOIs with close-in stellar companions  (2608.13527 - Littlefield et al., 13 Aug 2026) in Figure caption for Figure \ref{fig:example_binary_TOI}, Section 2 (Sample)

Previous analyses have similarly noted that the true origin of the transit signal cannot be uniquely determined because of the strongly blended K2 point-spread function \citep[e.g.,][]{2022MNRAS.509.1075C}. We therefore regard EPIC~211407755 as an ambiguous but still plausible planet candidate, rather than as a statistically validated planet.

— A chemo-dynamical search for planet-candidate hosts of possible extragalactic origin  (2608.13895 - Tiancheng et al., 14 Aug 2026) in Section 3.2, False-positive Vetting of the Planet Candidates

That study found that the transit signal could originate from either stellar component and noted that the system had previously been flagged as a possible nearby eclipsing-binary configuration. It also reported the inferred planetary radius under each of the two possible host-star scenarios. We therefore classify TIC~239541449 as a planet candidate in a resolved binary system. The signal is likely astrophysical and periodic, but the true host star and intrinsic companion radius remain uncertain.

— A chemo-dynamical search for planet-candidate hosts of possible extragalactic origin  (2608.13895 - Tiancheng et al., 14 Aug 2026) in Section 3.2, False-positive Vetting of the Planet Candidates