50 research outputs found
Soft Confinement for Polymer Solutions
As a model of soft confinement for polymers, we investigated equilibrium
shapes of a flexible vesicle that contains a phase-separating polymer solution.
To simulate such a system, we combined the phase field theory (PFT) for the
vesicle and the self-consistent field theory (SCFT) for the polymer solution.
We observed a transition from a symmetric prolate shape of the vesicle to an
asymmetric pear shape induced by the domain structure of the enclosed polymer
solution. Moreover, when a non-zero spontaneous curvature of the vesicle is
introduced, a re-entrant transition between the prolate and the dumbbell shapes
of the vesicle is observed. This re-entrant transition is explained by
considering the competition between the loss of conformational entropy and that
of translational entropy of polymer chains due to the confinement by the
deformable vesicle. This finding is in accordance with the recent experimental
result reported by Terasawa, et al.Comment: 5 pages, 3 figure
H Emission Nebulosity Associated with KH 15D
An H emission filament is found in close proximity to the unique object
KH 15D using the adaptive optics system of the Subaru Telescope. The morphology
of the filament, the presence of spectroscopic outflow signatures observed by
Hamilton et al., and the detection of extended H emission from KH 15D by
Deming, Charbonneau, & Harrington suggest that this filament arises from
shocked H in an outflow. The filament extends about 15" to the north of KH
15D.Comment: 11 pages, 3 figures, 1 table. Astrophysical Journal Letters, in pres
A Subarcsecond Companion to the T Tauri Star AS 353B
Adaptive optics imaging of the bright visual T Tauri binary AS 353 with the
Subaru Telescope shows that it is a hierarchical triple system. The secondary
component, located 5.6" south of AS 353A, is resolved into a subarcsecond
binary, AS 353Ba and Bb, separated by 0.24". Resolved spectroscopy of the two
close components shows that both have nearly identical spectral types of about
M1.5. Whereas AS 353A and Ba show clear evidence for an infrared excess, AS
353Bb does not. We discuss the possible role of multiplicity in launching the
large Herbig-Haro flow associated with AS 353A.Comment: AASTeXv5.0, 21 pages, 5 figures, Astronomical Journal, in pres
`imaka - a ground-layer adaptive optics system on Maunakea
We present the integration status for `imaka, the ground-layer adaptive
optics (GLAO) system on the University of Hawaii 2.2-meter telescope on
Maunakea, Hawaii. This wide-field GLAO pathfinder system exploits Maunakea's
highly confined ground layer and weak free-atmosphere to push the corrected
field of view to ~1/3 of a degree, an areal field approaching an order of
magnitude larger than any existing or planned GLAO system, with a FWHM ~ 0.33
arcseconds in the visible and near infrared. We discuss the unique design
aspects of the instrument, the driving science cases and how they impact the
system, and how we will demonstrate these cases on the sky.Comment: 9 pages, 5 figure
First Detection of NaI D lines in High-Redshift Damped Lyman-alpha Systems
A Near-infrared (1.18-1.35 micron) high-resolution spectrum of the
gravitationally-lensed QSO APM 08279+5255 was obtained with the IRCS mounted on
the Subaru Telescope using the AO system. We detected strong NaI D 5891,5897
doublet absorption in high-redshift DLAs at z=1.062 and 1.181, confirming the
presence of NaI, which was first reported for the rest-frame UV NaI
3303.3,3303.9 doublet by Petitjean et al. This is the first detection of NaI D
absorption in a high-redshift (z>1) DLA. In addition, we detected a new NaI
component in the z=1.062 DLA and four new components in the z=1.181 DLA. Using
an empirical relationship between NaI and HI column density, we found that all
"components" have large HI column density, so that each component is classified
as DLA absorption. We also detected strong NaI D absorption associated with a
MgII system at z=1.173. Because no other metal absorption lines were detected
in this system at the velocity of the NaI absorption in previously reported
optical spectra (observed 3.6 years ago), we interpret this NaI absorption
cloud probably appeared in the line of sight toward the QSO after the optical
observation. This newly found cloud is likely to be a DLA based upon its large
estimated HI column density. We found that the N(NaI)/N(CaII) ratios in these
DLAs are systematically smaller than those observed in the Galaxy; they are
more consistent with the ratios seen in the Large Magellanic Cloud. This is
consistent with dust depletion generally being smaller in lower metallicity
environments. However, all five clouds of the z=1.181 system have a high
N(NaI)/N(CaII) ratio, which is characteristic of cold dense gas. We tentatively
suggest that the host galaxy of this system may be the most significant
contributor to the gravitational-lens toward APM 08279+5255.Comment: 22 pages, 6 Postscript figures, 3 tables, ApJ in press (Vol.643, 2
June 2006
Direct Observation of the Extended Molecular Atmosphere of o Cet by Differential Spectral Imaging with an Adaptive Optics System
We present new measurements of the diameter of o Cet (Mira) as a function of
wavelength in the 2.2 micron atmospheric window using the adaptive optics
system and the infrared camera and spectrograph mounted on the Subaru
Telescope. We found that the angular size of the star at the wavelengths of CO
and H2O absorption lines were up to twice as large as the continuum
photosphere. This size difference is attributable to the optically thick CO and
H2O molecular layers surrounding the photosphere. This measurement is the first
direct differential spectroscopic imaging of stellar extension that resolves
individual molecular lines with high spectral-resolution observations. This
observation technique is extremely sensitive to differences in spatial profiles
at different wavelengths; we show that a difference in diameter much smaller
than the point spread function can be measured.Comment: 6 pages, 3 figures, accepted for publication in PAS
Current Performance and On-Going Improvements of the 8.2 m Subaru Telescope
An overview of the current status of the 8.2 m Subaru Telescope constructed
and operated at Mauna Kea, Hawaii, by the National Astronomical Observatory of
Japan is presented. The basic design concept and the verified performance of
the telescope system are described. Also given are the status of the instrument
package offered to the astronomical community, the status of operation, and
some of the future plans. The status of the telescope reported in a number of
SPIE papers as of the summer of 2002 are incorporated with some updates
included as of 2004 February. However, readers are encouraged to check the most
updated status of the telescope through the home page,
http://subarutelescope.org/index.html, and/or the direct contact with the
observatory staff.Comment: 18 pages (17 pages in published version), 29 figures (GIF format),
This is the version before the galley proo