Volume 551, March 2013
|Number of page(s)||10|
|Published online||04 March 2013|
On high-contrast characterization of nearby, short-period exoplanets with giant segmented-mirror telescopes
Max-Planck Institüt für Astronomie, Königstuhl 17,
Received: 14 December 2012
Accepted: 21 January 2013
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 RP = 1−8 R⊕ and equilibrium temperatures ≲400 K should be accessible around stars within 8 pc 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 RP = 1−2 R⊕ and 2−4 R⊕ occur with equal frequency, I predict a 40% chance that a planet with RP = 1−2 R⊕ and equilibrium temperature 200–250 K 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.
Key words: planets and satellites: general / planets and satellites: detection / instrumentation: adaptive optics / methods: numerical / techniques: high angular resolution
© ESO, 2013
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