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We present velocity-resolved spectro-astrometric imaging of the 4.7 $\mu$mrovibrational lines of CO gas in protoplanetary disks using the CRIRES highresolution infrared spectrometer on the Very Large Telescope (VLT). The methodas applied to three disks with known dust gaps or inner holes out to 4-45 AU(SR 21, HD 135344B and TW Hya) achieves an unprecedented spatial resolution of$0.1-0.5$ AU. While one possible gap formation mechanism is dynamical clearingby giant planets, other equally good explanations (stellar companions, graingrowth, photo-evaporation) exist. One way of distinguishing between differentscenarios is the presence and distribution of gas inside the dust gaps.Keplerian disk models are fit to the spectro-astrometric position-velocitycurves to derive geometrical parameters of the molecular gas. We determine theposition angles and inclinations of the inner disks with accuracies as good as1-2\degr, as well as the radial extent of the gas emission. Molecular gas isdetected well inside the dust gaps in all three disks. The gas emission extendsto within a radius of 0.5 AU for HD 135344B and to 0.1 AU for TW Hya,supporting partial clearing by a $< 1-10 M_{\rm Jup}$ planetary body as thecause of the observed dust gaps, or removal of the dust by extensive graincoagulation and planetesimal formation. The molecular gas emission in SR 21appears to be truncated within $\sim 7 $AU, which may be caused by completedynamical clearing by a more massive companion. We find a smaller inclinationangle of the inner disk of TW Hya than that determined for the outer disk,suggestive of a disk warp. We also detect significant azimuthal asymmetries inthe SR 21 and HD 135344B inner disks.

Spectro-astrometric imaging of molecular gas within protoplanetary disk gaps