A Previously Underexplored Regime in TESS: Minute-scale Eclipses Reveal 10 White Dwarf-Cool M-dwarf Binaries

Cavalier, T.; de Wit, J.; Timmermans, M.; Rackham, B. V.; Albornoz, M.; Burdanov, A. Y.; Barkaoui, K.; Triaud, A. H. M. J.; Burgasser, A. J.; Demory, B.-O.; Ducrot, E.; Gillon, M.; Gómez Maqueo Chew, Y.; Hooton, M. J.; Pedersen, P. P.; Queloz, D.; Zúñiga-Fernández, S.
Bibliographical reference

The Astrophysical Journal Letters

Advertised on:
10
2026
Number of authors
17
IAC number of authors
1
Citations
1
Refereed citations
0
Description
Short-period white-dwarf--main-sequence (WDMS) binaries provide direct constraints on the outcomes of common-envelope (CE) evolution and the survival of low-mass companions during engulfment. We report the discovery and confirmation of 10 totally eclipsing WD + cool-M-dwarf binaries identified through a search tailored to minute-scale eclipses in Transiting Exoplanet Survey Satellite (TESS) high-cadence data and validated with SPECULOOS multiband photometry. The systems have orbital periods of a few hours and companion masses of 0.094--0.175 M⊙. Our pilot search of ~37,000 Gaia-selected WDs increases the number of WD+M systems first identified through TESS by an order of magnitude, demonstrating that minute-scale WD eclipses occupy a previously underexplored discovery regime for TESS. SPECULOOS follow-up establishes the WDs as the sources of the eclipse signals, while chromatic eclipse dilution and broadband spectral-energy-distribution (SED) modeling provide complementary constraints on the component properties. These systems extend the TESS-discovered eclipsing WD+M population toward lower companion masses and establish an effective, scalable framework for expanding the search from the ~37,000 WDs analyzed here to a pool of O(106) Gaia WD candidates with TESS photometry.