Three Long-period Transiting Giant Planets from TESS*

We report the discovery and orbital characterization of three new transiting warm giant planets. These systems were initially identified as presenting single-transit events in the light curves generated from the full-frame images of the Transiting Exoplanet Survey Satellite. Follow-up radial velocity measurements and additional light curves were used to determine the orbital periods and confirm the planetary nature of the candidates. The planets orbit slightly metal-rich late F- and early G-type stars. We find that TOI 4406b has a mass of M ( P ) = 0.30 +/- 0.04 M (J), a radius of R ( P ) = 1.00 +/- 0.02 R (J), and a low-eccentricity orbit (e = 0.15 +/- 0.05) with a period of P = 30.08364 +/- 0.00005 days. TOI 2338b has a mass of M ( P ) = 5.98 +/- 0.20 M (J), a radius of R ( P ) = 1.00 +/- 0.01 R (J), and a highly eccentric orbit (e = 0.676 +/- 0.002) with a period of P = 22.65398 +/- 0.00002 days. Finally, TOI 2589b has a mass of M ( P ) = 3.50 +/- 0.10 M (J), a radius of R ( P ) = 1.08 +/- 0.03 R (J), and an eccentric orbit (e = 0.522 +/- 0.006) with a period of P = 61.6277 +/- 0.0002 days. TOI 4406b and TOI 2338b are enriched in metals compared to their host stars, while the structure of TOI 2589b is consistent with having similar metal enrichment to its host star.

Automated summary

We have discovered and characterized three new warm giant planets with transiting properties. These planets were initially detected through single-transit events in the light curves generated by the Transiting Exoplanet Survey Satellite. Further measurements and analysis confirmed their orbital periods and planetary nature. The planets orbit stars with slightly higher metal content. TOI 4406b has a low eccentricity orbit with a period of 30.08364 days, TOI 2338b has a highly eccentric orbit with a period of 22.65398 days, and TOI 2589b has an eccentric orbit with a period of 61.6277 days. TOI 4406b and TOI 2338b exhibit metal enrichment compared to their host stars, while TOI 2589b is consistent with having similar metal enrichment.