A long-period (P = 61.8 d) M5V dwarf eclipsing a Sun-like star from TESS and NGTS

The Transiting Exoplanet Survey Satellite has produced a large number of single-transit event candidates which are being monitored by the Next Generation Transit Survey (NGTS). We observed a second epoch for the TIC-231005575 system (T_mag = 12.06 and $T_{\rm eff} = 5500 \pm 85\, \mathrm{ K}$ ) with NGTS and a third epoch with Las Cumbres Observatory's telescope in South Africa to constrain the orbital period ( $P = 61.777\, \mathrm{ d}$ ). Subsequent radial velocity measurements with CORALIE revealed the transiting object has a mass of M₂ = 0.128 ± 0.003 M_⊙, indicating the system is a G-M binary. The radius of the secondary is R₂ = 0.154 ± 0.008 R_⊙ and is consistent with MESA models of stellar evolution to better than 1σ.