TOI-2427 HARPS RVs and activity indicators

These discoveries require ground-based follow-up observations, including high-precision Doppler spectroscopy, to rule out false positive scenarios and measure the mass of the transiting planets. In this study, we present an intensive Doppler follow-up campaign of the TESS object of interest TOI-2427, carried out with the High Accuracy Radial velocity Planet Searcher (HARPS) spectrograph to determine the mass of the previously validated transiting planet (TOI-2427 b) and search for additional orbiting companions.

By analyzing TESS transit photometry alongside our HARPS radial velocity measurements, we spectroscopically confirmed the transiting planet TOI-2427 b, which orbits its host star every ~1.3d. We also discovered the presence of a second non-transiting planetary companion with an orbital period of ~5.15d, which is very close to four times the orbital period of the inner transiting planet. We found that TOI-2427 b is a short-period, high-density super-Earth with a mass of Mb=5.69_-0.50_^+0.51^M_{Earth}_ and a radius of Rb=1.64_-0.11_^+0.12^R_{Earth}_, implying a mean density of {rho}b=7.1_-0.4_^+0.8^g/cm^3^.