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

The yield of Earth-like planets will likely be a primary science metric for future space-based missions that will drive telescope aperture size. Maximizing the exoEarth candidate yield is therefore critical to minimizing the required aperture. Here we describe a method for exoEarth candidate yield maximization that simultaneously optimizes, for the first time, the targets chosen for observation, the number of visits to each target, the delay time between visits, and the exposure time of every observation. This code calculates both the detection time and multi-wavelength spectral characterization time required for planets. We also refine the astrophysical assumptions used as inputs to these calculations, relying on published estimates of planetary occurrence rates as well as theoretical and observational constraints on terrestrial planet sizes and classical habitable zones. Given these astrophysical assumptions, optimistic telescope and instrument assumptions, and our new completeness code that produces the highest yields to date, we suggest lower limits on the aperture size required to detect and characterize a statistically-motivated sample of exoEarths.

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.

We present SCExAO/CHARIS high-contrast imaging/JHK integral field spectroscopy of κ And b, a directly-imaged low-mass companion orbiting a nearby B9V star. We detect κ And b at a high signal-to-noise and extract high precision spectrophotometry using a new forward-modeling algorithm for (A-)LOCI complementary to KLIP-FM developed by Corresponding author: Thayne Currie thayne.m.currie@nasa.gov,currie@naoj.org Currie et al. Pueyo et al. (2016). κ And b's spectrum best resembles that of a low-gravity L0-L1 dwarf (L0-L1γ). Its spectrum and luminosity are very well matched by 2MASSJ0141-4633 and several other 12.5-15 M J free floating members of the 40 M yr-old Tuc-Hor Association, consistent with a system age derived from recent interferometric results for the primary, a companion mass at/near the deuterium-burning limit (13 +12 −2 M J ), and a companion-to-primary mass ratio characteristic of other directly-imaged planets (q ∼ 0.005 +0.005 −0.001 ). We did not unambiguously identify additional, more closely-orbiting companions brighter and more massive than κ And b down to ρ ∼ 0. ′′ 3 (15 au). SCExAO/CHARIS and complementary Keck/NIRC2 astrometric points reveal clockwise orbital motion. Modeling points towards a likely eccentric orbit: a subset of acceptable orbits include those that are aligned with the star's rotation axis. However, κ And b's semimajor axis is plausibly larger than 75 au and in a region where disk instability could form massive companions.Deeper κ And high-contrast imaging and low-resolution spectroscopy from extreme AO systems like SCExAO/CHARIS and higher resolution spectroscopy from Keck/OSIRIS or, later, IRIS on the Thirty Meter Telescope could help clarify κ And b's chemistry and whether its spectrum provides an insight into its formation environment.

Two studies utilizing sparse aperture-masking (SAM) interferometry and H α differential imaging have reported multiple jovian companions around the young solar-mass star, LkCa 15 (LkCa 15 bcd): the first claimed direct detection of infant, newly formed planets ("protoplanets"). We present new near-infrared direct imaging/spectroscopy from the Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) system coupled with the Coronagraphic High 2 Angular Resolution Imaging Spectrograph (CHARIS) integral field spectrograph and multi-epoch thermal infrared imaging from Keck/NIRC2 of LkCa 15 at high Strehl ratios. These data provide the first direct imaging look at the same wavelengths and in the same locations where previous studies identified the LkCa 15 protoplanets, and thus offer the first decisive test of their existence.The data do not reveal these planets. Instead, we resolve extended emission tracing a dust disk with a brightness and location comparable to that claimed for LkCa 15 bcd. Forward-models attributing this signal to orbiting planets are inconsistent with the combined SCExAO/CHARIS and Keck/NIRC2 data. An inner disk provides a more compelling explanation for the SAM detections and perhaps also the claimed H α detection of LkCa 15 b.We conclude that there is currently no clear, direct evidence for multiple protoplanets orbiting LkCa 15, although the system likely contains at least one unseen jovian companion. To identify jovian companions around LkCa 15 from future observations, the inner disk should be detected and its effect modeled, removed, and shown to be distinguishable from planets. Protoplanet candidates identified from similar systems should likewise be clearly distinguished from disk emission through modeling.

We conduct a statistical analysis of a combined sample of direct imaging data, totalling nearly 250 stars. The stars cover a wide range of ages and spectral types, and include five detections (κ And b, two ∼60 M J brown dwarf companions in the Pleiades, PZ Tel B, and CD−35 2722B). For some analyses we add a currently unpublished set of SEEDS observations, including the detections GJ 504b and GJ 758B. We conduct a uniform, Bayesian analysis of all stellar ages using both membership in a kinematic moving group and activity/rotation age indicators. We then present a new statistical method for computing the likelihood of a substellar distribution function. By performing most of the integrals analytically, we achieve an enormous speedup over brute-force Monte Carlo. We use this method to place upper limits on the maximum semimajor axis of the distribution function derived from radialvelocity planets, finding model-dependent values of ∼30-100 AU. Finally, we model the entire substellar sample, from massive brown dwarfs to a theoretically motivated cutoff at ∼5 M J , with a single power-law distribution. We find that p(M, a) ∝ M −0.65±0.60 a −0.85±0.39 (1σ errors) provides an adequate fit to our data, with 1.0%-3.1% (68% confidence) of stars hosting 5-70 M J companions between 10 and 100 AU. This suggests that many of the directly imaged exoplanets known, including most (if not all) of the low-mass companions in our sample, formed by fragmentation in a cloud or disk, and represent the low-mass tail of the brown dwarfs.

We report high-resolution (0.07 arcsec) near-infrared polarized intensity images of the circumstellar disk around the star 2MASS J16042165-2130284 obtained with HiCIAO mounted on the Subaru 8.2 m telescope. We present our H-band data, which clearly exhibits a resolved, face-on disk with a large inner hole for the first time at infrared wavelengths. We detect the centrosymmetric polarization pattern in the circumstellar material as has been observed in other disks. Elliptical fitting gives the semimajor axis, semiminor axis, and position angle (P.A.) of the disk as 63 AU, 62 AU, and -14 • , respectively. The disk is asymmetric, with one dip located at P.A.s of ∼85 • . Our observed disk size agrees well with a previous study of dust and CO emission at submillimeter wavelength with Submillimeter Array. Hence, the near-infrared light is interpreted as scattered light reflected from the inner edge of the disk. Our observations also detect an elongated arc (50 AU) extending over the disk inner hole. It emanates at the inner edge of the western side of the disk, extending inward first, then curving to the northeast. We discuss the possibility that the inner hole, the dip, and the arc that we have observed may be related to the existence of unseen bodies within the disk.

We present high resolution H-band polarized intensity (P I; FWHM = 0. ′′ 1: 14 AU) and L ′ -band imaging data (FWHM = 0. ′′ 11: 15 AU) of the circumstellar disk around the weak-lined T Tauri star PDS 70 in Centaurus at a radial distance of 28 AU (0. ′′ 2) up to 210 AU (1. ′′ 5). In both images, a giant inner gap is clearly resolved for the first time, and the radius of the gap is ∼70 AU. Our data show that the geometric center of the disk shifts by ∼6 AU toward the minor axis. We confirm that the brown dwarf companion candidate to the north of PDS 70 is a background star based on its proper motion. As a result of SED fitting by Monte Carlo radiative transfer modeling, we infer the existence of an optically thick inner disk at a few AU. Combining our observations and modeling, we classify the disk of PDS 70 as a pre-transitional disk. Furthermore, based on the analysis of L ′ -band imaging data, we put an upper limit mass of companions at ∼30 to ∼50M J within the gap. Taking account of the presence of the large and sharp gap, we suggest that the gap could be formed by dynamical interactions of sub-stellar companions or multiple unseen giant planets in the gap.