Spectra of wide companions to planet-host stars

We also report two new stellar M dwarf companions to one G and one metal-rich K star. We infer stellar and substellar binary frequencies for our complete sample of 37 targets of 5.4+/-3.8% and 2.7+/-2.7% (1 sigma confidence level), respectively, for projected physical separations larger than ~60-160AU assuming the range of distances of planet-host stars (24-75pc). These values are comparable to the frequencies of non planet-host stars.

We find that the period-eccentricity trend holds with a lack of multiple systems with planets at large eccentricities (e>0.2) for periods less than 40-days. However, the lack of planets more massive than 2.5 Jupiter masses and short periods (<40-days) orbiting single stars is not so obvious due to recent discoveries by ground-based transit surveys and space missions.