We report the detection of a new candidate exoplanet around the metal-rich star \tau ^ { 1 } Gruis .
With M sin i = 1.23 \pm 0.18 M _ { JUP } , a period of 1326 \pm 300 d and an orbit with an eccentricity of 0.14 \pm 0.14 it adds to the growing population of long period exoplanets with near-circular orbits .
This population now comprises more than 20 % of known exoplanets .

When the companion to \tau ^ { 1 } Gruis is plotted together with all exoplanets found by the Anglo-Australian Planet Search and other radial velocity searches we find evidence for a peak in the number of short-period exoplanets , followed by a minimum of planets between around 7 and 50 days and then an apparent rise in the number of planets per unit radius that seems to set in by a hundred days , indicating more planets farther from the host star .
This is very different from the gaussian-like period distribution found for stellar companions .
This lends support to the idea that once a clearing in the inner protoplanetary disk develops , it halts the inward migration of planets .
In particular , the smooth distribution of exoplanets arising from planetary migration through a disk is altered by an accumulation of exoplanets at the point where the disk has been cleared out .