We present results from an adaptive optics survey for substellar and stellar companions to Sun-like stars .
The survey targeted 266 F5–K5 stars in the 3 Myr to 3 Gyr age range with distances of 10–190 pc .
Results from the survey include the discovery of two brown dwarf companions ( HD 49197B and HD 203030B ) , 24 new stellar binaries , and a triple system .
We infer that the frequency of 0.012–0.072 M _ { \sun } brown dwarfs in 28–1590 AU orbits around young solar analogs is 3.2 ^ { +3.1 } _ { -2.7 } % ( 2 \sigma limits ) .
The result demonstrates that the deficiency of substellar companions at wide orbital separations from Sun-like stars is less pronounced than in the radial velocity “ brown dwarf desert. ” We infer that the mass distribution of companions in 28–1590 AU orbits around solar-mass stars follows a continuous dN / dM _ { 2 } \propto M _ { 2 } ^ { -0.4 } relation over the 0.01–1.0 M _ { \sun } secondary mass range .
While this functional form is similar to the that for < 0.1 M _ { \sun } isolated objects , over the entire 0.01–1.0 M _ { \sun } range the mass functions of companions and of isolated objects differ significantly .
Based on this conclusion and on similar results from other direct imaging and radial velocity companion surveys in the literature , we argue that the companion mass function follows the same universal form over the entire range between 0–1590 AU in orbital semi-major axis and \approx 0.01–20 M _ { \sun } in companion mass .
In this context , the relative dearth of substellar versus stellar secondaries at all orbital separations arises naturally from the inferred form of the companion mass function .