49 research outputs found
Polarimetric Imaging of Large Cavity Structures in the Pre-transitional Protoplanetary Disk around PDS 70: Observations of the disk
We present high resolution H-band polarized intensity (PI; 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 ~50MJ 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.Comment: accepted by APJ
Constraining the Movement of the Spiral Features and the Locations of Planetary Bodies within the AB Aur System
We present new analysis of multi-epoch, H-band, scattered light images of the
AB Aur system. We used a Monte Carlo, radiative transfer code to simultaneously
model the system's SED and H-band polarized intensity imagery. We find that a
disk-dominated model, as opposed to one that is envelope dominated, can
plausibly reproduce AB Aur's SED and near-IR imagery. This is consistent with
previous modeling attempts presented in the literature and supports the idea
that at least a subset of AB Aur's spirals originate within the disk. In light
of this, we also analyzed the movement of spiral structures in multi-epoch
H-band total light and polarized intensity imagery of the disk. We detect no
significant rotation or change in spatial location of the spiral structures in
these data, which span a 5.8 year baseline. If such structures are caused by
disk-planet interactions, the lack of observed rotation constrains the location
of the orbit of planetary perturbers to be >47 AU.Comment: 8 pages, 3 figures, 1 table, Accepted to Ap
High-Resolution Submillimeter and Near-Infrared Studies of the Transition Disk around Sz 91
To reveal the structures of a transition disk around a young stellar object
in Lupus, Sz 91, we have performed aperture synthesis 345 GHz continuum and
CO(3--2) observations with the Submillimeter Array (\sim1\arcsec--3\arcsec
resolution), and high-resolution imaging of polarized intensity at the
-band by using the HiCIAO instrument on the Subaru Telescope (0\farcs25
resolution). Our observations successfully resolved the inner and outer radii
of the dust disk to be 65 AU and 170 AU, respectively, which indicates that Sz
91 is a transition disk source with one of the largest known inner holes. The
model fitting analysis of the spectral energy distribution reveals an H
mass of M_\sun in the cold (30 K) outer part at
AU by assuming a canonical gas-to-dust mass ratio of 100, although a
small amount ( M_\sun) of hot (180 K) dust possibly
remains inside the inner hole of the disk. The structure of the hot component
could be interpreted as either an unresolved self-luminous companion body (not
directly detected in our observations) or a narrow ring inside the inner hole.
Significant CO(3--2) emission with a velocity gradient along the major axis of
the dust disk is concentrated on the Sz 91 position, suggesting a rotating gas
disk with a radius of 420 AU. The Sz 91 disk is possibly a rare disk in an
evolutionary stage immediately after the formation of protoplanets because of
the large inner hole and the lower disk mass than other transition disks
studied thus far