Eiji Akiyama

Subaru imaging of asymmetric features in a transitional disk in upper Scorpius

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

Local Enhancement of the Surface Density in the Protoplanetary Ring Surrounding HD 142527

H

Seeds Adaptive Optics Imaging of the Asymmetric Transition Disk OPH IRS 48 in Scattered Light

-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

New Panoramic View of 12CO and 1.1 mm Continuum Emission in the Orion A Giant Molecular Cloud. I. Survey Overview and Possible External Triggers of Star Formation

^{\circ}

Detailed structure of the outer disk around HD 169142 with polarized light in H-band

, respectively. The disk is asymmetric, with one dip located at P.A.s of

High-resolution submillimeter and near-infrared studies of the transition disk around Sz 91

\sim85^{\circ}

Surface geometry of protoplanetary disks inferred from near-infrared imaging polarimetry

. 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.

The Structure of Pre-transitional Protoplanetary Disks. II. Azimuthal Asymmetries, Different Radial Distributions of Large and Small Dust Grains in PDS 70

We report ALMA observations of dust continuum, 13CO J=3--2, and C18O J=3--2 line emission toward a gapped protoplanetary disk around HD 142527. The outer horseshoe-shaped disk shows the strong azimuthal asymmetry in dust continuum with the contrast of about 30 at 336 GHz between the northern peak and the southwestern minimum. In addition, the maximum brightness temperature of 24 K at its northern area is exceptionally high at 160 AU from a star. To evaluate the surface density in this region, the grain temperature needs to be constrained and was estimated from the optically thick 13CO J=3--2 emission. The lower limit of the peak surface density was then calculated to be 28 g cm-2 by assuming a canonical gas-to-dust mass ratio of 100. This finding implies that the region is locally too massive to withstand self-gravity since Toomres Q <~1--2, and thus, it may collapse into a gaseous protoplanet. Another possibility is that the gas mass is low enough to be gravitationally stable and only dust grains are accumulated. In this case, lower gas-to-dust ratio by at least 1 order of magnitude is required, implying possible formation of a rocky planetary core.

The Sizes and Depletions of the Dust and Gas Cavities in the Transitional Disk J160421.7-213028

We present the first resolved near infrared imagery of the transition disk Oph IRS 48 (WLY 2-48), which was recently observed with ALMA to have a strongly asymmetric sub-millimeter flux distribution. H-band polarized intensity images show a

Significant gas-to-dust ratio asymmetry and variation in the disk of HD 142527 and the indication of gas depletion

\sim