GJ 4274 time series

From the SPIRou spectra, we also derive and analyze the longitudinal large scale magnetic field, B_ell_, and the surface temperature variations, dTemp. We combine the SPIRou RV data with some RV measurements from CARMENES, to model possible planetary signals with both circular and eccentric orbits. The activity is modeled with a Quasi-Periodic Gaussian Process.

We also perform injection-recovery tests to the photometric TESS data to assess transit detectability. We report the discovery of two exoplanets around the nearby M dwarf star GJ 4274. Both planets are in a circular orbit with respective periods of Pb=1.6339+/-0.0001 and Pc=69.6^+0.3^_-1.1_d, this second period being located beyond the habitable zone.

From their RV semi-amplitude signals (Kb=5.10^+0.70^_-0.67_m/s and Kc=4.11+/-0.64m/s), we derived their minimum masses that are respectively mbsini=2.97^+0.54^_-0.50_M_{Earth}_ and m_c_sini=8.4+/-1.3M_{Earth}_. TESS photometric observations rule out most transit scenarios, including the inner planet, yielding a maximum inclination for the planet b of $i_b \leq 83^{\circ}$. We do not detect RV variations related to stellar magnetic activity in the SPIRou time series, despite a prominent large-scale magnetic field of up to 206^+158^_-62_G of amplitude.

We derive a rotation period for the star of 4.600^+0.011^_-0.006_d from the activity indicators. The two planets reported belong to the super-Earth/sub-Neptune class. GJ 4274 b has one of the shortest orbital periods among planets around <0.2M_{sun}_ M dwarfs within 15 pc, while GJ 4274 c lies in a sparsely populated region of the mass-period diagram.

Their discovery adds to the census of nearby planetary systems and provides promising targets for future surveys.