We present 2.0Y2.4 m integral field spectroscopy at adaptive optics spatial resolution (~0.1 00 ) obtained with the Near-infrared Integral Field Spectrograph (NIFS) at Gemini North Observatory of six classical T Tauri stars: T Tau, DG Tau, XZ Tau, HL Tau, RW Aur, and HV Tau C. In all cases, the v ¼ 1Y 0 S(1) (2.12 m) emission is detected at spatially extended distances from the central stars. Moreover, HL Tau, T Tau, RWAur, and HV Tau C have H 2 that extends to projected distances of more than~200 AU from the stars. Integrated over the IFU field, most of the H 2 emission is not spatially coincident with the location of continuum flux. Multiple H 2 transitions detected in the K-band spectra show that level populations are typical of gas in thermal equilibrium with excitation temperatures in the 1800Y 2300 K range. Three of the stars have H 2 velocity profiles that are centered approximately at the stellar radial velocity, and three show velocity shifts with respect to the system. Each of the stars studied here exhibit H 2 morphologies, spatial extents, excitation temperatures, and kinematics that are most consistent with shock-excited emission from the inner regions of the known Herbig-Haro energy flows or from spatially extended wide-angle winds encompassing the outflows rather than predominantly from H 2 stimulated quiescently by UV or X-ray emission from the central stars. The data presented in this study highlights the sensitivity of adaptive-opticsYfed integral field spectroscopy for spatially resolving emission line structures in the environments of bright young stars.

We present the first near-IR scattered light detection of the transitional disk associated with the Herbig Ae star MWC 758 using data obtained as part of the Strategic Exploration of Exoplanets and Disks with Subaru, and 1.1µm HST/NICMOS data. While sub-millimeter studies suggested there is a dustdepleted cavity with r=0. ′′ 35, we find scattered light as close as 0.1 ′′ (20-28 AU) from the star, with no visible cavity at H, K', or K s . We find two small-scaled spiral structures which asymmetrically shadow the outer disk. We model one of the spirals using spiral density wave theory, and derive a disk aspect ratio of h∼0.18, indicating a dynamically warm disk. If the spiral pattern is excited by a perturber, we estimate its mass to be 5 +3 −4 M J , in the range where planet filtration models predict accretion continuing onto the star. Using a combination of non-redundant aperture masking data at L ′ and angular differential imaging with Locally Optimized Combination of Images at K ′ and K s , we exclude stellar or massive brown dwarf companions within 300 mas of the Herbig Ae star, and all but planetary mass companions exterior to 0. ′′ 5. We reach 5-σ contrasts limiting companions to planetary masses, 3-4 M J at 1. ′′ 0 and 2 M J at 1. ′′ 55 using the COND models. Collectively, these data strengthen the case for MWC 758 already being a young planetary system. Subject headings: circumstellar matter instrumentation: high angular resolution polarization planetary systems: protoplanetary disks stars: individual (MWC 758) waves

We report results of a spectropolarimetric and photometric monitoring of the weakline T Tauri star LkCa 4 within the MaTYSSE programme, involving ESPaDOnS at the Canada-France-Hawaii Telescope. Despite an age of only 2 Myr and a similarity with prototypical classical T Tauri stars, LkCa 4 shows no evidence for accretion and probes an interesting transition stage for star and planet formation. Large profile distortions and Zeeman signatures are detected in the unpolarized and circularlypolarized lines of LkCa 4 using Least-Squares Deconvolution (LSD), indicating the presence of brightness inhomogeneities and magnetic fields at the surface of LkCa 4.Using tomographic imaging, we reconstruct brightness and magnetic maps of LkCa 4 from sets of unpolarized and circularly-polarized LSD profiles. The largescale field is strong and mainly axisymmetric, featuring a ≃2 kG poloidal component and a ≃1 kG toroidal component encircling the star at equatorial latitudes -the latter making LkCa 4 markedly different from classical T Tauri stars of similar mass and age. The brightness map includes a dark spot overlapping the magnetic pole and a bright region at mid latitudes -providing a good match to the contemporaneous photometry. We also find that differential rotation at the surface of LkCa 4 is small, typically ≃5.5× weaker than that of the Sun, and compatible with solid-body rotation.Using our tomographic modelling, we are able to filter out the activity jitter in the RV curve of LkCa 4 (of full amplitude 4.3 km s −1 ) down to a rms precision of 0.055 km s −1 . Looking for hot Jupiters around young Sun-like stars thus appears feasible, even though we find no evidence for such planets around LkCa 4.