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What did our solar system look like in its infancy, ... ... when the planets were forming? We cannot travel back in time to take an image of the early [...]

The directcharacterization of exoplanetary systems with high-contrast imaging is among the highest priorities for the broader exoplanet community. As large space missions will be necessary for detecting and characterizing exo-Earth twins, developing the techniques and technology for direct imaging of exoplanets is a driving focus for the community. For the first time, JWST will directly observe extrasolar planets at mid-infrared wavelengths beyond 5 μm, deliver detailed spectroscopy revealing much more precise chemical abundances and atmospheric conditions, and provide sensitivity to analogs of our solar system ice-giant planets at wide orbital separations, an entirely new class of exoplanet. However, in order to maximize the scientific output over the lifetime of the mission, an exquisite understanding of the instrumental performance of JWST is needed as early in the mission as possible. In this paper, we describe our 55 hr Early Release Science Program that will utilize all four JWST instruments to extend the characterization of planetary-mass companions to ∼15 μm as well as image a circumstellar disk in the mid-infrared with unprecedented sensitivity. Our program will also assess the performance of the observatory in the key modes expected to be commonly used for exoplanet direct imaging and spectroscopy, optimize data calibration and processing, and generate representative data sets that will enable a broad user base to effectively plan for general observing programs in future Cycles.

The article discusses the developments in the study of astronomy. It cites the creation of infant exoplanetary systems to determine the evolution of the solar system. It presents the works conducted by Vincent Piétu of the France-based Institut de Radioastronomie Millimétrique, Sean Andrews of the Center for Astrophysics, and Andrea Isella of the California Institute of Technology (Caltech).

We present the first multicolor view of the scattered light disk of the Herbig Ae star HD 163296, based on coronagraphic observations from the Hubble Space Telescope Advanced Camera for Surveys (HST ACS). Radial profile fits of the surface brightness along the disk's semimajor axis indicate that the disk is not continuously flared, and extends to ~540 AU. The disk's color (V [?] I) = 1.1 at a radial distance of 3.5 '' is redder than the observed stellar color (V [?] I) = 0.15. This red disk color might be indicative of either an evolution in the grain size distribution (i.e., grain growth) and/or composition, both of which would be consistent with the observed nonflared geometry of the outer disk. We also identify a single ansa morphological structure in our F435W ACS data, which is absent from earlier epoch F606W and F814W ACS data, but corresponds to one of the two ansae observed in archival HST Space Telescope Imaging Spectrograph (STIS) coronagraphic data. Following transformation to similar bandpasses, we find that the scattered light disk of HD 163296 is 1 mag arcsec[?]2 fainter at 3.5 '' in the STIS data than in the ACS data. Moreover, variations are seen in (1) the visibility of the ansa(e) structures, (2) the relative surface brightness of the ansa(e) structures, and (3) the (known) intrinsic polarization of the system. These results indicate that the scattered light from the HD 163296 disk is variable. We speculate that the inner disk wall, which Sitko et al. suggests has a variable scale height as diagnosed by near-IR SED variability, induces variable self-shadowing of the outer disk. We further speculate that the observed surface brightness variability of the ansa(e) structures may indicate that the inner disk wall is azimuthally asymmetric.

Infrared photometry and spectroscopy covering a time span of a quarter-century are presented for HD 31648 (MWC 480) and HD 163296 (MWC 275). Both are isolated Herbig Ae stars that exhibit signs of active accretion, including driving bipolar flows with embedded Herbig-Haro (HH) objects. HD 163296 was found to be relatively quiescent photometrically in its inner disk region, with the exception of a major increase in emitted flux in a broad wavelength region centered near 3 mm in 2002. In contrast, HD 31648 has exhibited sporadic changes in the entire 3-13 mm region throughout this span of time. In both stars, the changes in the 1-5 mm flux indicate structural changes in the region of the disk near the dust sublimation zone, possibly causing its distance from the star to vary with time. Repeated thermal cycling through this region will result in the preferential survival of large grains, and an increase in the degree of crystallinity. The variability observed in these objects has important consequences for the interpretation of other types of observations. For example, source variability will compromise models based on interferometry measurements unless the interferometry observations are accompanied by nearly simultaneous photometric data.

HST NICMOS PSF-subtracted coronagraphic observations of HD 181327 have revealed the presence of a ringlike disk of circumstellar debris seen in 1.1 mm light scattered by the disk grains, surrounded by a diffuse outer region of lower surface brightness. The annular disk appears to be inclined by 31.deg7 +- 1.deg6 from face-on, with the disk major-axis P.A. at 107deg +- 2deg. The total 1.1 mm flux density of the light scattered by the disk (at 1.''2 < r < 5.''0) of 9.6 +- 0.8 mJy is 0.17% +- 0.015% of the starlight. Seventy percent of the light from the scattering grains appears to be confined in a 36 AU wide annulus centered on the peak of the radial surface brightness (SB) profile 86.3 +- 3.9 AU from the star, well beyond the characteristic radius of thermal emission estimated from IRAS and Spitzer flux densities, assuming blackbody grains ([?]22 AU). The 1.1 mm light scattered by the ring (1) appears bilaterally symmetric, (2) exhibits directionally preferential scattering well represented by a Henyey-Greenstein scattering phase function with gHG = 0.30 +- 0.03, and (3) has a median SB (over all azimuth angles) at the 86.3 AU radius of peak SB of 1.00 +- 0.07 mJy arcsec-2. No photocentric offset is seen in the ring relative to the position of the central star. A low SB diffuse halo is seen in the NICMOS image to a distance of ~4''. Deeper 0.6 mm Hubble Space Telescope (HST) ACS PSF-subtracted coronagraphic observations reveal a faint (V [?] 21.5 mag arcsec-2) outer nebulosity at 4'' < r < 9'', asymmetrically brighter to the north of the star. We discuss models of the disk and properties of its grains, from which we infer a maximum vertical scale height of 4-8 AU at the 87.6 AU radius of maximum surface density, and a total maximum dust mass of collisionally replenished grains with minimum grain sizes of [?]1 mm of [?]4MMoon.

Chandra X-ray imaging spectroscopy of the nearby Herbig Ae star HD 163296 at 100 AU angular resolution is reported. A pointlike, soft (kT ~ 0.5 keV), emission-line source is detected at the location of the star with an X-ray luminosity of 4 x 1029 ergs s-1 (log LX/Lbol = -5.48). In addition, faint emission along the direction of a previously detected Lya-emitting jet and Herbig-Haro outflow may be present. The relatively low luminosity, lack of a hard spectral component, and absence of strong X-ray variability in HD 163296 can be explained as originating from optically thin shock-heated gas accreting onto the stellar surface along magnetic field lines. This would require a (dipole) magnetic field strength at the surface of HD 163296 of at least ~100 G and perhaps as high as several kG. HD 163296 joins the T Tauri star TW Hya in being the only examples known to date of pre-main-sequence stars whose quiescent X-ray emission appears to be completely dominated by accretion.

The STIS CCD camera on the Hubble Space Telescope (HST) was used to take deep optical images near the K2 V main-sequence star [?] Eridani in an attempt to find an optical counterpart of the dust ring previously imaged by submillimeter observations. Upper limits for the optical brightness of the dust ring are determined and discussed in the context of the scattered starlight expected from plausible dust models. We find that even if the dust is smoothly distributed in symmetrical rings, the optical surface brightness of the dust, as measured with the HST STIS CCD clear aperture at 55 AU from the star, cannot be brighter than about 25 STMAG arcsec-2. This upper limit excludes some solid-grain models for the dust ring that can fit the IR and submillimeter data. Magnitudes and positions for [?]59 discrete objects between 12.''5 and 58'' from [?] Eri are reported. Most if not all of these objects are likely to be background stars and galaxies.

We present 30 optical spectra and 49 photometric epochs sampling the first 517 days after discovery of supernova (SN) 1999em and derive its distance through the expanding photosphere method (EPM). SN 1999em is shown to be a Type II-plateau (II-P) event, with a photometric plateau lasting until about 100 days after explosion. We identify the dominant ions responsible for most of the absorption features seen in the optical portion of the spectrum during the plateau phase. Using the weakest unblended absorption features to estimate photospheric velocity, we find the distance to SN 1999em to be D = 8.2 ± 0.6 Mpc, with an explosion date of HJD 2,451,475.6 ± 1.4, or 5.3 ± 1.4 days before discovery. We show that this distance estimate is about 10% closer than the distance that results if the strong Fe ii??4924, 5018, 5169 absorption features, which have often been used in previous EPM studies, are used to estimate photospheric velocity.

The debris disks surrounding the pre-main-sequence stars HD 31648 and HD 163296 were observed spectroscopically between 3 and 14 mm. Both stars possess a silicate emission feature at 10 mm that resembles that of the star b Pictoris and those observed in solar system comets. The structure of the band is consistent with a mixture of olivine and pyroxene material, plus an underlying continuum of unspecified origin. The similarity in both size and structure of the silicate band suggests that the material in these systems had a processing history similar to that in our own solar system prior to the time that the grains were incorporated into comets.

Recent discoveries of planets orbiting several nearby solar-mass stars have focussed renewed attention on the frequency and evolution of planetary systems and their evolutionary precursors around both solar and intermediate (2 ≤ M/M ⊙ ≤ 8) mass stars. As a result of a wealth of new observations at all wavelengths of the circumstellar material around the nearest of the young intermediate-mass stars, the so-called Herbig Ae/Be (HAeBe) stars, we are beginning to see how these systems are similar to the solar mass objects, and how they differ. A review of the recent literature is presented, including the evolutionary status of the stars, binary frequency and the star forming environment, the morphology of the circumstellar material, including the first direct detections of disks in Keplerian rotation around these objects, and mass loss and infall phenomena. Prospects for advances in this research area as a result of advances in instrumentation are reviewed.

We find a new substellar companion to the Pleiades member star, Pleiades HII 3441, using the Subaru telescope with adaptive optics. The discovery is made as part of the high-contrast imaging survey to search for planetary-mass and substellar companions in the Pleiades and young moving groups. The companion has a projected separation of 0${^{\prime\prime}_{.}}$49 ± 0${^{\prime\prime}_{.}}$02 (66 ± 2 au) and a mass of 68 ± 5 MJbased on three observations in the J-, H-, and Ks-bands. The spectral type is estimated to be M7 (∼2700 K), and thus no methane absorption is detected in the Hband. Our Pleiades observations result in the detection of two substellar companions including one previously reported among 20 observed Pleiades stars, and indicate that the fraction of substellar companions in the Pleiades is about $10.0^{+26.1}_{-8.8}$%. This is consistent with multiplicity studies of both the Pleiades stars and other open clusters.

We present the first near-infrared scattered-light detection of the transitional disk around V1247 Ori, which was obtained using high-resolution polarimetric differential imaging observations with Subaru/HiCIAO. Our imaging in the Hband reveals the disk morphology at separations of ∼0${^{\prime\prime}_{.}}$14–0${^{\prime\prime}_{.}}$86 (54–330 au) from the central star. The polarized intensity image shows a remarkable arc-like structure toward the southeast of the star, whereas the fainter northwest region does not exhibit any notable features. The shape of the arm is consistent with an arc of 0${^{\prime\prime}_{.}}$28 ± 0${^{\prime\prime}_{.}}$09 in radius (108 au from the star), although the possibility of a spiral arm with a small pitch angle cannot be excluded. V1247 Ori features an exceptionally large azimuthal contrast in scattered, polarized light; the radial peak of the southeastern arc is about three times brighter than the northwestern disk measured at the same distance from the star. Combined with the previous indication of an inhomogeneous density distribution in the gap at ≲46 au, the notable asymmetry in the outer disk suggests the presence of unseen companions and/or planet-forming processes ongoing in the arc.

We present high-contrast H-band polarized intensity images of the transitional disk around the young solar-like star LkCa 15. By utilizing Subaru/HiCIAO for polarimetric differential imaging, the angular resolution and the inner working angle reach 0${^{\prime\prime}_{.}}$07 and r= 0${^{\prime\prime}_{.}}$1, respectively. We obtained a clearly resolved gap (width ≲ 27 au) at ∼48 au from the central star. This gap is consistent with images reported in previous studies. We also confirmed the existence of a bright inner disk with a misaligned position angle of 13° ± 4° with respect to that of the outer disk, i.e., the inner disk is possibly warped. The large gap and the warped inner disk both point to the existence of a multiple planetary system with a mass of ≲ 1 MJup.

Coronagraphic imagery of the circumstellar disk around HD 169142 in H-band polarized intensity (PI) with Subaru/HiCIAO is presented. The emission scattered by dust particles at the disk surface in 0${^{\prime\prime}_{.}}$2 ≤ r≤ 1${^{\prime\prime}_{.}}$2, or 29 ≤ r≤ 174 au, is successfully detected. The azimuthally averaged radial profile of the PI shows a double power-law distribution, in which the PIs in r= 29–52 au and r= 81.2–145 au respectively show r−3dependence. These two power-law regions are connected smoothly with a transition zone (TZ), exhibiting an apparent gap in r= 40–70 au. The PI in the inner power-law region shows a deep minimum whose location seems to coincide with the point source at λ = 7 mm. This can be regarded as another sign of a protoplanet in the TZ. The observed radial profile of the PI is reproduced by a minimally flaring disk with an irregular surface density distribution, an irregular temperature distribution, or with a combination of both. The depletion factor of surface density in the inner power-law region (r< 50 au) is derived to be ≥ 0.16 from a simple model calculation. The obtained PI image also shows small-scale asymmetries in the outer power-law region. Possible origins for these asymmetries include corrugation of the scattering surface in the outer region, and a shadowing effect by a puffed-up structure in the inner power-law region.

We compared the number of faint stars detected in deep survey fields with the current stellar distribution model of the Galaxy and found that the detected number in the Hband is significantly smaller than the predicted number. This indicates that M-dwarfs, the major component, are fewer in the halo and the thick disk. We used archived data of several surveys in both the north and south field of GOODS (Great Observatories Origins Deep Survey), MODS (MOIRCS Deep Survey) in GOODS-N, and ERS (Early Release Science) and CANDELS (Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey) in GOODS-S. The number density of M-dwarfs in the halo has to be 20% ± 13% relative to that in the solar vicinity, in order for the detected number of stars fainter than 20.5 mag in the Hband to match with the predicted value from the model. In the thick disk, the number density of M-dwarfs must be reduced (52% ± 13%) or the scale height must be decreased (∼ 600 pc). Alternatively, overall fractions of the halo and thick disks can be significantly reduced to achieve the same effect, because our sample mainly consists of faint M-dwarfs. Our results imply that the M-dwarf population in regions distant from the Galactic plane is significantly smaller than previously thought. We then discussed the implications this has on the suitability of the model predictions for the prediction of non-companion faint stars in direct imaging extrasolar planet surveys by using the best-fitting number densities.

We carried out an imaging survey for extrasolar planets around stars in the Pleiades (125 Myr, 135 pc) in the $H$and $K_{\rm S}$bands using HiCIAO combined with adaptive optics, AO188, on the Subaru telescope. We found 13 companion candidates fainter than 14.5 mag in the $H$band around 9 stars. Five of these 13 were confirmed to be background stars by measurement of their proper motion. One was not found in the second epoch observation, and thus was not a background or companion object. One had multi-epoch images, but the precision of its proper motion was not sufficient to conclude whether it was a background object. Four other candidates are waiting for second-epoch observations to determine their proper motion. Finally, the remaining two were confirmed to be 60 $M_{\rm {J}}$brown dwarf companions orbiting around HD 23514 (G0) and HII 1348 (K5), respectively, as had been reported in previous studies. In our observations, the average detection limit for a point source was 20.3 mag in the $H$band beyond 1$.{\prime\prime}$5 from the central star. On the basis of this detection limit, we calculated the detection efficiency to be 90% for a planet with 6 to 12 Jovian masses and a semi-major axis of 50–1000 AU. For this reason we extrapolated the distribution of the planet mass and the semi-major axis derived from radial velocity observations, and adopted the planet evolution model Baraffe et al. (2003, A&A, 402, 701). Since there was no detection of a planet, we estimated the frequency of such planets to be less than 17.9% (2 $\sigma$) around one star of the Pleiades cluster.

We report that HAT-P-7 has a common proper motion stellar companion. The companion is located at $ \sim$3$ .\!\!\!''$9 to the east and estimated to be an M5.5V dwarf based on its colors. We also confirm the presence of a third companion, which was first reported by Winn et al. (2009, ApJ, 703, L99), based on long-term radial velocity measurements. We revisit the migration mechanism of HAT-P-7b given to the presence of those companions, and propose the sequential Kozai migration as a likely scenario in this system. This scenario may explain the reason for an outlier in the discussion of the spin-orbit alignment timescale for HAT-P-7b by Albrecht et al. (2012, ApJ, 757, 18).

We present $ H$-band polarimetric imagery of UX Tau A taken with HiCIAO/AO188 on the Subaru Telescope. UX Tau A has been classified as a pre-transitional disk object, with a gap structure separating its inner and outer disks. Our imagery taken with the 0$ \rlap{\hskip1pt .}''$15 (21 AU) radius coronagraphic mask has revealed a strongly polarized circumstellar disk surrounding UX Tau A, which extends to 120 AU, at a spatial resolution of 0$ \rlap{\hskip1pt .}''$1 (14 AU). It is inclined by 46$ ^{\circ}$$ \pm$2$ ^{\circ}$, since the west side is nearest. Although SED modeling and sub-millimeter imagery have suggested the presence of a gap in the disk, with the inner edge of the outer disk estimated to be located at 25–30 AU, we detect no evidence of a gap at the limit of our inner working angle (23 AU) at the near-infrared wavelength. We attribute the observed strong polarization (up to 66%) to light scattering by dust grains in the disk. However, neither polarization models of the circumstellar disk based on Rayleigh-scattering nor Mie-scattering approximations were consistent with the observed azimuthal profile of the polarization degrees of the disk. Instead, a geometric optics model of the disk with nonspherical grains with radii of 30 $ \mu$m is consistent with the observed profile. We suggest that the dust grains have experienced frequent collisional coagulations, and have grown in the circumstellar disk of UX Tau A.