MMT/AO 5 μm imaging constraints on the existence of giant planets orbiting fomalhaut at 13-40 AU

Abstract

A candidate ≲3 M Jup extrasolar planet was recently imaged by Kalas etal. using Hubble Space Telescope/Advanced Camera for Surveys and Keck II at 127 (96AU) separation from the nearby (d = 7.7 pc) young (200 Myr) A2V star Fomalhaut. Here, we report results from M-band (4.8 μm) imaging of Fomalhaut on 2006 December 5 using the Clio IR imager on the 6.5 m MMT with the adaptive secondary mirror. Our images are sensitive to giant planets at orbital radii comparable to the outer solar system (10-40AU). Comparing our 5σ M-band photometric limits to theoretical evolutionary tracks for substellar objects, our results rule out the existence of planets with masses >2 M Jup from 13 to 40AU and objects >13 M Jup from 8 to 40AU. © 2009. The American Astronomical Society. All rights reserved.