We present high-resolution, H-band, imaging observations, collected with Subaru/HiCIAO, of the scattered light from the transitional disk around SAO 206462 (HD 135344B). Although previous submm imagery suggested the existence of the dust-depleted cavity at r ≤ 46 AU, our observations reveal the presence of scattered light components as close as 0. ′′ 2 (∼ 28 AU) from the star. Moreover, we have discovered two small-scale spiral structures lying within 0. ′′ 5 (∼ 70 AU). We present models for the spiral structures using the spiral density wave theory, and derive a disk aspect ratio of h ∼ 0.1, which is consistent with previous sub-mm observations. This model can potentially give estimates of the temperature and rotation profiles of the disk based on dynamical processes, independently from sub-mm observations. It also predicts the evolution of the spiral structures, which can be observable on timescales of 10-20 years, providing conclusive tests of the model. While we cannot uniquely identify the origin of these spirals, planets embedded in the disk may be capable of exciting the observed morphology. Assuming that this is the case, we can make predictions on the locations and, possibly, the masses of the unseen planets. Such planets may be detected by future multi-wavelengths observations.

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 present the discovery of a transiting exoplanet candidate in the K2 Field-1 with an orbital period of 9.1457 hr: K2-22b. The highly variable transit depths, ranging from ∼0% to 1.3%, are suggestive of a planet that is disintegrating via the emission of dusty effluents. We characterize the host star as an M-dwarf with T eff ; 3800 K. We have obtained ground-based transit measurements with several 1-m class telescopes and with the GTC. These observations (1) improve the transit ephemeris; (2) confirm the variable nature of the transit depths; (3) indicate variations in the transit shapes; and (4) demonstrate clearly that at least on one occasion the transit depths were significantly wavelength dependent. The latter three effects tend to indicate extinction of starlight by dust rather than by any combination of solid bodies. The K2 observations yield a folded light curve with lower time resolution but with substantially better statistical precision compared with the ground-based observations. We detect a significant "bump" just after the transit egress, and a less significant bump just prior to transit ingress. We interpret these bumps in the context of a planet that is not only likely streaming a dust tail behind it, but also has a more prominent leading dust trail that precedes it. This effect is modeled in terms of dust grains that can escape to beyond the planetʼs Hill sphere and effectively undergo "Roche lobe overflow," even though the planetʼs surface is likely underfilling its Roche lobe by a factor of 2.

Direct Imaging of a Cold Jovian Exoplanet in Orbit around the Sun-like Star GJ 504Kuzuhara, M.; et al., [Unknown]; Thalmann, C.D. General rightsIt is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulationsIf you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: http://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. Download date: 13 May 2018The Astrophysical Journal, 774:11 (18pp) ABSTRACT Several exoplanets have recently been imaged at wide separations of >10 AU from their parent stars. These span a limited range of ages (<50 Myr) and atmospheric properties, with temperatures of 800-1800 K and very red colors (J − H > 0.5 mag), implying thick cloud covers. Furthermore, substantial model uncertainties exist at these young ages due to the unknown initial conditions at formation, which can lead to an order of magnitude of uncertainty in the modeled planet mass. Here, we report the direct-imaging discovery of a Jovian exoplanet around the Sun-like star GJ 504, detected as part of the SEEDS survey. The system is older than all other known directly imaged planets; as a result, its estimated mass remains in the planetary regime independent of uncertainties related to choices of initial conditions in the exoplanet modeling. Using the most common exoplanet cooling model, and given the system age of 160 +350 −60 Myr, GJ 504b has an estimated mass of 4 +4.5 −1.0 Jupiter masses, among the lowest of directly imaged planets. Its projected separation of 43.5 AU exceeds the typical outer boundary of ∼30 AU predicted for the core accretion mechanism. GJ 504b is also significantly cooler (510 +30 −20 K) and has a bluer color (J − H = −0.23 mag) than previously imaged exoplanets, suggesting a largely cloud-free atmosphere accessible to spectroscopic characterization. Thus, it has the potential of providing novel insights into the origins of giant planets as well as their atmospheric properties.