HIP 41378 radial velocity curves

In particular, the RV data strongly favour an orbital period of Pd=278-days for planet d and refine the orbital period of planet e to Pe=393^+3^_-5_days. We measure a new mass of Mf=25+/-5M_{Earth}_ for HIP 41378 f, confirming its super-puff nature with a bulk density of {rho}f=0.166^+0.033^_-0.036_g/cm^3^. We also confirm the planetary nature of HIP 41378 g, a non-transiting planet with a 63-day period, and determine its minimum mass.

In addition, the RVs reveal a long-period signal, with P=2602^+468^_-433_days, which we attribute to the candidate planet HIP 41378 h, although a stellar magnetic cycle cannot be excluded. Finally, we investigate the system's dynamical architecture and resonant structure, assess its completeness by constraining additional undetected planets, and discuss the implications for the origin and internal structure of the remarkable planet HIP 41378 f.