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

TL;DR

This paper confirms a sub-Saturn exoplanet, TOI-1194 b, and a very low mass star companion, TOI-1251 B, using TESS data and ground-based follow-up, demonstrating the effectiveness of multi-telescope campaigns for exoplanet validation.

Contribution

It presents the first confirmation of TOI-1194 b and TOI-1251 B through combined TESS and ground-based observations, including multiband photometry and spectroscopy.

Findings

TOI-1194 b has an orbital period of 2.310644 days and radius of 0.767 R_J.

TOI-1251 B has an orbital period of 5.963054 days and radius of 0.947 R_J.

Ground-based follow-up confirms the planetary and stellar companions.

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 $96.5\pm1.5$ $M_J$, 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 multiband 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 $2.310644\pm0.000001$ d, and radius is $0.767_{-0.041}^{+0.045}$ $R_J$, and amplitude of RV curve is $69.4_{-7.3}^{+7.9}$ m/s. TOI-1251 B is confirmed based on the multiband 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 $9849_{-40}^{+42}$ m/s.