2006ApJ...649..436E

We discuss our high-precision radial velocity results of a sample of 90 M dwarfs observed with the Hobby-Eberly Telescope and the Harlan J. Smith 2.7 m Telescope at McDonald Observatory, as well as the ESO VLT and the Keck I telescopes, within the context of the overall frequency of Jupiter-mass planetary companions to main-sequence stars. None of the stars in our sample show variability indicative of a giant planet in a short-period orbit, with a≤1 AU. We estimate an upper limit of the frequency f of close-in Jovian planets around M dwarfs as <1.27% (at the 1 σ confidence level). Furthermore, we determine that the efficiency of our survey in noticing planets in circular orbits is 98% for companions with msini>3.8M_Jand a≤0.7 AU. For eccentric orbits (e=0.6) the survey completeness is 95% for all planets with msini>3.5M_Jand a≤0.7 AU. Our results point toward a generally lower frequency of close-in Jovian planets for M dwarfs as compared to FGK-type stars. This is an important piece of information for our understanding of the process of planet formation as a function of stellar mass.