Two long-period transiting exoplanets

Using a joint modeling of the light curves and radial velocities, we computed the orbital parameters of the system and were able to precisely measure the mass and radius of the transiting planets. We report the discovery of two massive, warm Jupiter-size planets, one transiting the F8-type star TOI-5153 and the other transiting the G1-type star NGTS-20 (=TOI-5152). From our spectroscopic analysis, both stars are metal-rich with a metallicity of 0.12 and 0.15.

Follow-up radial velocity observations were carried out with CORALIE, CHIRON, FEROS, and HARPS. TOI-5153 hosts a 20.33 day period planet with a planetary mass of 3.26_-0.17_^+0.18^M_J_, a radius of 1.06+/-0.04R_J_, and an orbital eccentricity of 0.091_-0.026_^+0.024^. NGTS-20 b is a 2.98_-0.15_^+0.16^M_J_ planet with a radius of 1.07+/-0.04R_J_ on an eccentric 0.432+/-0.023 orbit with an orbital period of 54.19-days.

Both planets are metal-enriched and their heavy element content is in line with the previously reported mass-metallicity relation for gas giants. Both warm Jupiters orbit moderately bright host stars, making these objects valuable targets for follow-up studies of the planetary atmosphere and measurement of the spin-orbit angle of the system.