Description
We report on the first star discovered to host a planet detected by radial velocity (RV) observations obtained within the CARMENES survey for exoplanets around M dwarfs. HD 147379 (V=8.9mag, M=0.58+/-0.08M_{sun}_), a bright M0.0 V star at a distance of 10.7pc, is found to undergo periodic RV variations with a semi-amplitude of K=5.1+/-0.4m/s and a period of P=86.54+/-0.06d. The RV signal is found in our CARMENES data, which were taken between 2016 and 2017, and is supported by HIRES/Keck observations that were obtained since 2000. The RV variations are interpreted as resulting from a planet of minimum mass m_P_sini=25+/-2M_{Earth}_, 1.5 times the mass of Neptune, with an orbital semi-major axis a=0.32au and low eccentricity (e<0.13). HD 147379 b is orbiting inside the temperate zone around the star, where water could exist in liquid form. The RV time-series and various spectroscopic indicators show additional hints of variations at an approximate period of 21.1d (and its first harmonic), which we attribute to the rotation period of the star.
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