Name/Affiliation: Benjamin Montet (Caltech, Harvard)
The Occurrence Rate of Giant Planets around M Dwarfs
Doppler-based planet surveys have discovered numerous giant planets but are incomplete beyond several AU. At larger star-planet separations, direct planet detection through high-contrast imaging has proven successful, but this technique is sensitive only to young planets and characterization relies upon theoretical evolution models. Recently, we have demonstrated that radial velocity measurements and high-contrast imaging can be combined to overcome these issues. The presence of widely separated companions can be deduced by identifying an acceleration (long-term "trend") in the stellar radial velocity. By obtaining high spatial resolution follow-up imaging observations, we rule out scenarios in which such accelerations are caused by stellar binary companions with high statistical confidence. Here, I will report results from an analysis of Doppler measurements of a sample of 111 M dwarf stars observed with a median time baseline of 11.8 years (Montet et al. 2014). By targeting stars that exhibit a radial velocity acceleration with adaptive optics imaging, we determine that 6.5% +/- 3.0% of M dwarf stars host one or more companions with masses in the range 1-13 Jupiter masses and orbital separations in the range 0-20 AU. We also find a very strong correlation between giant planet occurrence at wide separations and stellar metallicity.