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Abstract We present an intensive effort to refine the mass and orbit of the enveloped terrestrial planet GJ 1214 b using 165 radial velocity (RV) measurements taken with the HARPS spectrograph over a period of 10 years. We conduct a joint analysis of the RVs with archival Spitzer/IRAC transits and measure a planetary mass and radius of 8.17 ± 0.43 M ⊕ and 2.742 − 0.053 + 0.050 R ⊕ . Assuming that GJ 1214 b is an Earth-like core surrounded by a H/He envelope, we measure an envelope mass fraction of X env = 5.24 − 0.29 + 0.30 %. GJ 1214 b remains a prime target for secondary eclipse observations of an enveloped terrestrial, the scheduling of which benefits from our constraint on the orbital eccentricity of 90 − 21 + 5 % of mid-M dwarfs with a known planet with mass ∈ 1, 10 M ⊕ and orbital period ∈ 0.5, 50 days, will host at least one additional planet. We rule out additional planets around GJ 1214 down to 3 M ⊕ within 10 days, such that GJ 1214 is a single-planet system within these limits. This result has a 44 − 5 + 9 probability given the prevalence of multiplanet systems around mid-M dwarfs. We also investigate mid-M-dwarf RV systems and show that the probability that all reported RV planet candidates are real planets is <12% at 99% confidence, although this statistical argument is unable to identify the probable false positives.
Cloutier et al. (Mon,) studied this question.