Two Long-period Low-mass Eclipsing Binaries Recovered from Gaia DR3 Spectroscopic Orbits and TESS Eclipses at the Predicted Conjunctions

Abstract A single-lined spectroscopic orbit predicts when its primary can be eclipsed. I searched the TESS two-minute light curves of the 826 stars of sectors 1, 2 and 13 with a Gaia DR3 SB1 orbit for dips at the predicted conjunctions, and report two long-period eclipsing systems, one uncatalogued, one catalogued at a wrong period. TIC 370324073 shows 28.7% primary and 3.4% secondary eclipses in five sectors, at the conjunctions of a 31.82 day orbit; TIC 155989956 shows 11.5% eclipses in four sectors on a 37.31 day orbit of eccentricity 0.53. Eclipse fits and the Gaia mass functions make the companions M dwarfs of at least 0.43 and 0.49 M ⊙ with radii of 0.42 and 0.47 R ⊙ , on the empirical mass–radius relation. A community user had posted the first star’s eclipses on ExoFOP as planet candidates. The method reaches long-period systems that catalogues miss.