Mass determination of two Jupiter-sized planets orbiting slightly evolved stars: TOI-2420 b and TOI-2485 b

Context. Hot and warm Jupiters might have undergone the same formation and evolution path, but the two populations exhibit different distributions of orbital parameters. This challenges our understanding of their actual origin. Aims. We report the results of our warm Jupiters survey, which was carried out with the CHIRON spectrograph within the KESPRINT collaboration. We addressed the question of the population origin by studying two planets that might help to bridge the gap between the two populations. Methods. We confirm two planets and determine their mass. One is a hot Jupiter (with an orbital period shorter than 10 days), TOI-2420 b, and the other is a warm Jupiter, TOI-2485 b. We analyzed them using a wide variety of spectral and photometric data in order to characterize these planetary systems. Results. We found that TOI-2420 b has an orbital period of Pb=5.8 days, a mass of Mb=0.9 MJ, and a radius of Rb=1.3 RJ, with a planetary density of 0.477 g cm−3. TOI-2485 b has an orbital period of Pb=11.2 days, a mass of Mb=2.4 MJ, and a radius of Rb=1.1 RJ with a density of 2.36 g cm−3. Conclusions. With the current parameters, the migration history for TOI-2420 b and TOI-2485 b is unclear: Scenarios of a high-eccentricity migration cannot be ruled out, and the characteristics of TOI-2485 b even support this scenario.