2,152 research outputs found
Development of 2MASS Catalog Server Kit
We develop a software kit called "2MASS Catalog Server Kit" to easily
construct a high-performance database server for the 2MASS Point Source Catalog
(includes 470,992,970 objects) and several all-sky catalogs. Users can perform
fast radial search and rectangular search using provided stored functions in
SQL similar to SDSS SkyServer. Our software kit utilizes open-source RDBMS, and
therefore any astronomers and developers can install our kit on their personal
computers for research, observation, etc. Out kit is tuned for optimal
coordinate search performance. We implement an effective radial search using an
orthogonal coordinate system, which does not need any techniques that depend on
HTM or HEALpix. Applying the xyz coordinate system to the database index, we
can easily implement a system of fast radial search for relatively small (less
than several million rows) catalogs. To enable high-speed search of huge
catalogs on RDBMS, we apply three additional techniques: table partitioning,
composite expression index, and optimization in stored functions. As a result,
we obtain satisfactory performance of radial search for the 2MASS catalog. Our
system can also perform fast rectangular search. It is implemented using
techniques similar to those applied for radial search. Our way of
implementation enables a compact system and will give important hints for a
low-cost development of other huge catalog databases.Comment: 2011 PASP accepte
Identifications and SEDs of the detected sources from the AKARI Deep Field South
In order to find counterparts of the detected objects in the AKARI Deep Field
South (ADFS) in all available wavelengths, we searched public databases (NED,
SIMBAD and others). Checking 500 sources brighter than 0.0482 Jy in the AKARI
Wide-S band, we found 114 sources with possible counterparts, among which 78
were known galaxies. We present these sources as well as our first attempt to
construct spectral energy distributions (SEDs) for the most secure and most
interesting sources among them, taking into account all the known data together
with the AKARI measurements in four bands.Comment: 4 pages, 10 figures, To appear in: the proceedings of the conference
"AKARI, a light to illuminate the misty Universe", February 16-19 2009, Toky
Monolithic Ge:Ga Detector Development for SAFARI
We describe the current status and the prospect for the development of
monolithic Ge:Ga array detector for SAFARI. Our goal is to develop a 64x64
array for the 45 -- 110 um band, on the basis of existing technologies to make
3x20 monolithic arrays for the AKARI satellite. For the AKARI detector we have
achieved a responsivity of 10 A/W and a read-out noise limited NEP (noise
equivalent power) of 10^-17 W/rHz. We plan to develop the detector for SAFARI
with technical improvements; significantly reduced read-out noise with newly
developed cold read-out electronics, mitigated spectral fringes as well as
optical cross-talks with a multi-layer antireflection coat. Since most of the
elemental technologies to fabricate the detector are flight-proven, high
technical readiness levels (TRLs) should be achieved for fabricating the
detector with the above mentioned technical demonstrations. We demonstrate some
of these elemental technologies showing results of measurements for test
coatings and prototype arrays.Comment: To appear in Proc. Workshop "The Space Infrared Telescope for
Cosmology & Astrophysics: Revealing the Origins of Planets and Galaxies".
Eds. A.M. Heras, B. Swinyard, K. Isaak, and J.R. Goicoeche
Spatial Distributions of Cold and Warm Interstellar Dust in M101 Resolved with AKARI/Far-Infrared Surveyor (FIS)
The nearby face-on spiral galaxy M101 has been observed with the Far-Infrared
Surveyor (FIS) onboard AKARI. The far-infrared four-band images reveal fine
spatial structures of M101, which include global spiral patterns, giant HII
regions embedded in outer spiral arms, and a bar-like feature crossing the
center. The spectral energy distribution of the whole galaxy shows the presence
of the cold dust component (18 K) in addition to the warm dust component (55
K). The distribution of the cold dust is mostly concentrated near the center,
and exhibits smoothly distributed over the entire extent of the galaxy, whereas
the distribution of the warm dust indicates some correlation with the spiral
arms, and has spotty structures such as four distinctive bright spots in the
outer disk in addition to a bar-like feature near the center tracing the CO
intensity map. The star-formation activity of the giant HII regions that
spatially correspond to the former bright spots is found to be significantly
higher than that of the rest of the galaxy. The latter warm dust distribution
implies that there are significant star-formation activities in the entire bar
filled with molecular clouds. Unlike our Galaxy, M101 is a peculiar normal
galaxy with extraordinary active star-forming regions.Comment: 18 pages, 9 figures, accepted for publication in PASJ AKARI special
issu
KNEE AND ANKLE JOINT KINEMATICS IN KENDO MOVEMENT AND THE REPEATABILITY
Kendo, a Japanese martial art of sword fighting, comprises strike and thrust motion against a specific target of a part of an opponent’s body. Among kendo athletes, chronic Achilles tendon (AT) injuries are frequently observed only on the left side probably because a main power source lies in the left side of the lower body for the repetitive forward-back bounding steps in the strike motion. It has been reported that the AT injury may be linked to abnormal joint biomechanics among runners. In order to make better clinical decision on the AT injury treatment in kendo athletes, therefore, we should focus on joint biomechanics of the left side of the lower extremity in kendo movement. The purpose of the study was to demonstrate the joint kinematics of knee and ankle in the kendo movement and quantify the repeatability
Development of an intense positron source using a crystal--amorphous hybrid target for linear colliders
In a conventional positron source driven by a few GeV electron beam, a high
amount of heat is loaded into a positron converter target to generate intense
positrons required by linear colliders, and which would eventually damage the
converter target. A hybrid target, composed of a single crystal target as a
radiator of intense gamma--rays, and an amorphous converter target placed
downstream of the crystal, was proposed as a scheme which could overcome the
problem.This paper describes the development of an intense positron source with
the hybrid target. A series of experiments on positron generation with the
hybrid target has been carried out with a 8--GeV electron beam at the KEKB
linac. We observed that positron yield from the hybrid target increased when
the incident electron beam was aligned to the crystal axis and exceeded the one
from the conventional target with the converter target of the same thickness,
when its thickness is less than about 2 radiation length. The measurements in
the temperature rise of the amorphous converter target was successfully carried
out by use of thermocouples. These results lead to establishment to the
evaluation of the hybrid target as an intense positron source.Comment: 17pages, 10figure
Star-galaxy separation by far-infrared color-color diagrams for the AKARI FIS All-Sky Survey (Bright Source Catalogue Version beta-1)
To separate stars and galaxies in the far infrared AKARI All-Sky Survey data,
we have selected a sample with the complete color information available in the
low extinction regions of the sky and constructed color-color plots for these
data. We looked for the method to separate stars and galaxies using the color
information. We performed an extensive search for the counterparts of these
selected All-Sky Survey sources in the NED and SIMBAD databases. Among 5176
objects, we found 4272 galaxies, 382 other extragalactic objects, 349 Milky Way
stars, 50 other Galactic objects, and 101 sources detected before in various
wavelengths but of an unknown origin. 22 sources were left unidentified. Then,
we checked colors of stars and galaxies in the far-infrared flux-color and
color-color plots. In the resulting diagrams, stars form two clearly separated
clouds. One of them is easy to be distinguished from galaxies and allows for a
simple method of excluding a large part of stars using the far-infrared data.
The other smaller branch, overplotting galaxies, consists of stars known to
have an infrared excess, like Vega and some fainter stars discovered by IRAS or
2MASS. The color properties of these objects in any case make them very
difficult to distinguish from galaxies. We conclude that the FIR color-color
diagrams allow for a high-quality star-galaxy separation. With the proposed
simple method we can select more that 95 % of galaxies rejecting at least 80 %
of stars.Comment: 20 pages, 41 figures, "Astronomy & Astrophysics", accepted, to appear
in the AKARI special issu
CSIP - a Novel Photon-Counting Detector Applicable for the SPICA Far-Infrared Instrument
We describe a novel GaAs/AlGaAs double-quantum-well device for the infrared
photon detection, called Charge-Sensitive Infrared Phototransistor (CSIP). The
principle of CSIP detector is the photo-excitation of an intersubband
transition in a QW as an charge integrating gate and the signal amplification
by another QW as a channel with very high gain, which provides us with
extremely high responsivity (10^4 -- 10^6 A/W). It has been demonstrated that
the CSIP designed for the mid-infrared wavelength (14.7 um) has an excellent
sensitivity; the noise equivalent power (NEP) of 7x10^-19 W/rHz with the
quantum efficiency of ~2%. Advantages of the CSIP against the other highly
sensitive detectors are, huge dynamic range of >10^6, low output impedance of
10^3 -- 10^4 Ohms, and relatively high operation temperature (>2K). We discuss
possible applications of the CSIP to FIR photon detection covering 35 -- 60 um
waveband, which is a gap uncovered with presently available photoconductors.Comment: To appear in Proc. Workshop "The Space Infrared Telescope for
Cosmology & Astrophysics: Revealing the Origins of Planets and Galaxies".
Eds. A.M. Heras, B. Swinyard, K. Isaak, and J.R. Goicoeche
An electro-chemo-mechanical analysis of solid oxide fuel cell considering evolution of microstructure in porous electrode using phase-field method
For the numerical simulation of oxygen potential distributions in Solid Oxide
Fuel Cell (SOFC), the time-evolution of the anode microstructure is reflected in the
macroscopic electrical conductivities and the amount of triple-phase boundaries. Once the
oxygen potential distributions are determined, the time-variation of the reduction-induced
strains due to nonstoichiometry of oxide materials is calculated along with the thermal strains.
These strains cause the macroscopic stresses in mutually constrained components. Thus, the
capability of the proposed method is demonstrated in characterizing the aging degradation of
the macroscopic electro-chemo-mechanical behavior of SOFC that is caused by the Nisintering
in cermet microstructures during long-period control
Properties of active galactic star-forming regions probed by imaging spectroscopy with the Fourier transform spectrometer (FTS) onboard AKARI
We investigate the structure of the interstellar medium (ISM) and identify
the location of possible embedded excitation sources from far-infrared (FIR)
line and mid-infrared continuum emission maps. We carried out imaging
spectroscopic observations of four giant Galactic star-forming regions with the
Fourier Transform Spectrometer (FTS) onboard AKARI. We obtained [OIII] 88
micron and [CII] 158 micron line intensity maps of all the regions:
G3.270-0.101, G333.6-0.2, NGC3603, and M17. For G3.270-0.101, we obtained
high-spatial-resolution [OIII] 88 micron line-emission maps and a FIR continuum
map for the first time, which imply that [OIII] 88 micron emission identifies
the excitation sources more clearly than the radio continuum emission. In
G333.6-0.2, we found a local [OIII] 88 micron emission peak, which is
indicative of an excitation source. This is supported by the 18 micron
continuum emission, which is considered to trace the hot dust distribution. For
all regions, the [CII] 158 micron emission is distributed widely as suggested
by previous observations of star-forming regions. We conclude that [OIII] 88
micron emission traces the excitation sources more accurately than the radio
continuum emission, especially where there is a high density and/or column
density gradient. The FIR spectroscopy provides a promising means of
understanding the nature of star-forming regions.Comment: 14 pages with 15 figures, accepted for publication in Astronomy and
Astrophysic
- …