2013A&A...551A..99C

Measurements of the frequency with which short-period planets occur around main sequence stars allows a direct prediction of the number and types of such planets that will be amenable to characterization by high-contrast instruments on future giant segmented-mirror telescopes (GSMTs). Adopting conservative assumptions, I predict of order 10 planets with radii R_p=1-8R_⊕ and equilibrium temperatures ≲400K should be accessible around stars within 8pc of the Sun. These numbers are roughly the same for both near-infrared observations of scattered starlight and mid-infrared observations of planetary thermal emission, with the latter observations demonstrating greater relative sensitivity to smaller and cooler planets. Adopting the conservative assumption that planets with R_p=1-2R_⊕ and R_p=2-4R_⊕ occur with equal frequency. I predict a 40% chance that a planet with R_p=1-2R_⊕ and equilibrium temperature 200-250K will accessible to high-contrast thermal infrared characterization; this would be a compelling object for further study. To validate these predictions, more detailed analyses are needed of the occurrence frequencies of low-mass planets around M dwarfs, both in the Kepler field and in the solar neighborhood. Several planets already discovered by radial velocity surveys will be accessible to near-infrared high-contrast GSMT observations, including the low-mass planets α Cen Bb and (depending on their albedos) GJ 139c and d, GJ 876b and c, and τ Cet b, c, and d; τ Cet f would be amenable to thermal infrared characterization. Further efforts to model the near-infrared reflectance and mid-infrared emission of these and other short-period planets are clearly warranted, and will pave the way for the interpretation of future high-contrast characterization of a variety of planets around the nearest stars.