Confirmation of a Sub-Saturn-size transiting exoplanet orbiting a G dwarf: TOI-1194 b and a very low mass companion star:TOI-1251 B from TESS

Abstract We report the confirmation of a sub-Saturn-size exoplanet, TOI-1194 b with a mass about 0.456 -0.051 +0.055 M J , and a very low mass companion star with a mass of about 96.47±1.5 M J , TOI-1251 B. Exoplanet candidates provided by the Transiting Exoplanet Survey Satellite (TESS) are suitable for further follow-up observations by ground-based telescopes with small and medium apertures. The analysis is performed based on data from several telescopes worldwide, including telescopes in the Sino-German multi-band photometric campaign, which aimed at confirming TESS Objects of Interest (TOIs) using ground-based small-aperture and medium-aperture telescopes, especially for long-period targets. TOI-1194 b is confirmed based on the consistent periodic transits depths from the multiband photometric data. We measure an orbital period of 2.310644±0.000001d, and radius is 0.767 -0.041 +0.045 R J , and amplitude of RV curve is 69.36 -7.31 +7.90 m/s. TOI-1251 B is confirmed based on the multi-band photometric and high-resolution spectroscopic data, whose orbiting period is 5.963054 -0.000001 +0.000002 d, the radius is 0.947 -0.033 +0.035 R J , and amplitude of RV curve is 9848.87 -40.08 +41.86 m/s.