138 research outputs found
Dense Clumps in Giant Molecular Clouds in the Large Magellanic Cloud: Density and Temperature Derived from CO() Observations
In order to precisely determine temperature and density of molecular gas in
the Large Magellanic Cloud, we made observations of optically thin
CO() transition by using the ASTE 10m telescope toward 9 peaks
where CO() clumps were previously detected with the same
telescope. The molecular clumps include those in giant molecular cloud (GMC)
Types I (with no signs of massive star formation), II (with HII regions only),
and III (with HII regions and young star clusters). We detected
CO() emission toward all the peaks and found that their
intensities are 3 -- 12 times lower than those of CO(). We
determined the intensity ratios of CO() to CO(),
, and CO() to CO(),
, at 45\arcsec resolution. These ratios were used for
radiative transfer calculations in order to estimate temperature and density of
the clumps. The parameters of these clumps range kinetic temperature
= 15 -- 200 K, and molecular hydrogen gas density
= 8 -- 7 cm. We confirmed
that the higher density clumps show higher kinetic temperature and that the
lower density clumps lower kinetic temperature at a better accuracy than in the
previous work. The kinetic temperature and density increase generally from a
Type I GMC to a Type III GMC. We interpret that this difference reflects an
evolutionary trend of star formation in molecular clumps. The
and kinetic temperature of the clumps are well correlated
with H flux, suggesting that the heating of molecular gas
= -- cm can be explained by stellar FUV
photons.Comment: 39 pages, 7 figures, 4 tables. Accepted for publication in The
Astronomical Journa
Quest of the first Japanese glacier in the northern part of the northern Japanese Alps
第2回極域科学シンポジウム/第34回気水圏シンポジウム 11月15日(火) 統計数理研究所 セミナー室
High Excitation Molecular Gas in the Galactic Center Loops; 12CO(J =2-1 and J =3-2) Observations
We have carried out 12CO(J =2-1) and 12CO(J =3-2) observations at spatial
resolutions of 1.0-3.8 pc toward the entirety of loops 1 and 2 and part of loop
3 in the Galactic center with NANTEN2 and ASTE. These new results revealed
detailed distributions of the molecular gas and the line intensity ratio of the
two transitions, R3-2/2-1. In the three loops, R3-2/2-1 is in a range from 0.1
to 2.5 with a peak at ~ 0.7 while that in the disk molecular gas is in a range
from 0.1 to 1.2 with a peak at 0.4. This supports that the loops are more
highly excited than the disk molecular gas. An LVG analysis of three
transitions, 12CO J =3-2 and 2-1 and 13CO J =2-1, toward six positions in loops
1 and 2 shows density and temperature are in a range 102.2 - 104.7 cm-3 and
15-100 K or higher, respectively. Three regions extended by 50-100 pc in the
loops tend to have higher excitation conditions as characterized by R3-2/2-1
greater than 1.2. The highest ratio of 2.5 is found in the most developed foot
points between loops 1 and 2. This is interpreted that the foot points indicate
strongly shocked conditions as inferred from their large linewidths of 50-100
km s-1, confirming the suggestion by Torii et al. (2010b). The other two
regions outside the foot points suggest that the molecular gas is heated up by
some additional heating mechanisms possibly including magnetic reconnection. A
detailed analysis of four foot points have shown a U shape, an L shape or a
mirrored-L shape in the b-v distribution. It is shown that a simple kinematical
model which incorporates global rotation and expansion of the loops is able to
explain these characteristic shapes.Comment: 59 pages, accepted to PAS
Temperature and Density in the Foot Points of the Molecular Loops in the Galactic Center; Analysis of Multi-J Transitions of 12CO(J=1-0, 3-2, 4-3, 7-6), 13CO(J=1-0) and C18O(J=1-0)
Fukui et al. (2006) discovered two molecular loops in the Galactic center and
argued that the foot points of the molecular loops, two bright spots at both
loops ends, represent the gas accumulated by the falling motion along the
loops, subsequent to magnetic flotation by the Parker instability. We have
carried out sensitive CO observations of the foot points toward l=356 deg at a
few pc resolution in the six rotational transitions of CO; 12CO(J=1-0, 3-2,
4-3, 7-6), 13CO(J=1-0) and C18O(J=1-0). The high resolution image of 12CO
(J=3-2) has revealed the detailed distribution of the high excitation gas
including U shapes, the outer boundary of which shows sharp intensity jumps
accompanying strong velocity gradients. An analysis of the multi-J CO
transitions shows that the temperature is in a range from 30-100 K and density
is around 10^3-10^4 cm^-3, confirming that the foot points have high
temperature and density although there is no prominent radiative heating source
such as high mass stars in or around the loops. We argue that the high
temperature is likely due to the shock heating under C-shock condition caused
by the magnetic flotation. We made a comparison of the gas distribution with
theoretical numerical simulations and note that the U shape is consistent with
numerical simulations. We also find that the region of highest temperature of
~100 K or higher inside the U shape corresponds to the spur having an upward
flow, additionally heated up either by magnetic reconnection or bouncing in the
interaction with the narrow neck at the bottom of the U shape. We note these
new findings further reinforce the magnetic floatation interpretation.Comment: 40 pages, 23 figures, accepted by PASJ on Vol.62 No.
Renal shear wave velocity by acoustic radiation force impulse did not reflect advanced renal impairment
[Aim] Acoustic radiation force impulse is a noninvasive method for evaluating tissue elasticity on ultrasound. Renal shear wave velocity measured by this technique has not been fully investigated in patients with renal disease. The aim of the present study was to compare renal shear wave velocity in end‐stage renal disease patients and that in patients without chronic kidney disease and to investigate influencing factors. [Methods] Renal shear wave velocities were measured in 59 healthy young subjects (control group), 31 subjects without chronic kidney disease (non‐CKD group), and 39 end‐stage renal disease patients (ESRD group). Each measurement was performed 10 times at both kidneys, and the mean value of eight of 10 measurements, excluding the maximum and minimum values, was compared. [Results] Renal shear wave velocity could be measured in all subjects. Renal shear wave velocity in the control group was higher than in the non‐CKD group and in the ESRD group, and no difference was found between the non‐CKD group and the ESRD group. Age and depth were negatively correlated to the renal shear wave velocity. In multiple regression analysis, age and depth were independent factors for renal shear wave velocity, while renal impairment was not. There was no difference between the non‐CKD group and the ESRD group, even when ages were matched and depth was adjusted. [Conclusion] Renal shear wave velocity was not associated with advanced renal impairment. However, it reflected alteration of renal aging, and this technique may be useful to detect renal impairment in the earlier stages
ASTE CO(3-2) Mapping toward the Whole Optical Disk of M 83: Properties of Inter-arm GMAs
We present a new on-the-fly (OTF) mapping of CO(J=3-2) line emission with the
Atacama Submillimeter Telescope Experiment (ASTE) toward the 8' x 8' (or 10.5 x
10.5 kpc at the distance of 4.5 Mpc) region of the nearby barred spiral galaxy
M 83 at an effective resolution of 25''. Due to its very high sensitivity, our
CO(J=3-2) map can depict not only spiral arm structures but also spur-like
substructures extended in inter-arm regions. This spur-like substructures in
CO(J=3-2) emission are well coincident with the distribution of massive star
forming regions traced by Halpha luminosity and Spitzer/IRAC 8 um emission. We
have identified 54 CO(J=3-2) clumps as Giant Molecular-cloud Associations
(GMAs) employing the CLUMPFIND algorithm, and have obtained their sizes,
velocity dispersions, virial masses, and CO luminosity masses. We found that
the virial parameter alpha, which is defined as the ratio of the virial mass to
the CO luminosity mass, is almost unity for GMAs in spiral arms, whereas there
exist some GMAs whose alpha are 3 -- 10 in the inter-arm region. We found that
GMAs with higher tend not to be associated with massive star forming
regions, while other virialized GMAs are. Since alpha mainly depends on
velocity dispersion of the GMA, we suppose the onset of star formation in these
unvirialized GMAs with higher alpha are suppressed by an increase in internal
velocity dispersions of Giant Molecular Clouds within these GMAs due to shear
motion.Comment: 42 pages, 16 figures, ApJ in press, version with high resolution
figures is available via
http://www.nro.nao.ac.jp/~kmuraoka/m83paper/m83aste-otf.pd
Production of cloned sei whale (Balaenoptera borealis) embryos by interspecies somatic cell nuclear transfer using enucleated pig oocytes
In this study, we examined the feasibility of using subzonal cell injection with electrofusion for interspecies somatic cell nuclear transfer (iSCNT) to produce sei whale embryos and to improve their developmental capacity by investigating the effect of osmolarity and macromolecules in the culture medium on the in vitro developmental capacity. Hybrid embryos produced by the electrofusion of fetal whale fibroblasts with enucleated porcine oocytes were cultured in modified porcine zygote medium-3 to examine the effects of osmolarity and fetal serum on their in vitro developmental capacity. More than 66% of the whale somatic cells successfully fused with the porcine oocytes following electrofusion. A portion (60~81%) of the iSCNT whale embryos developed to the two- to four-cell stages, but no embryos were able to reach the blastocyst stage. This developmental arrest was not overcome by increasing the osmolarity of the medium to 360 mOsm or by the addition of fetal bovine or fetal whale serum. Our results demonstrate that sei whale-porcine hybrid embryos may be produced by SCNT using subzonal injection and electrofusion. The pig oocytes partly supported the remodeling and reprogramming of the sei whale somatic cell nuclei, but they were unable to support the development of iSCNT whale embryos to the blastocyst stage
Warm and Dense Molecular Gas in the N159 Region: 12CO J=4-3 and 13CO J=3-2 Observations with NANTEN2 and ASTE
New 12CO J=4-3 and 13CO J=3-2 observations of the N159 region in the Large
Magellanic Cloud have been made. The 12CO J=4-3 distribution is separated into
three clumps. These new measurements toward the three clumps are used in
coupled calculations of molecular rotational excitation and line radiation
transfer, along with other transitions of the 12CO as well as the isotope
transitions of 13CO. The temperatures and densities are determined to be
~70-80K and ~3x10^3 cm-3 in N159W and N159E and ~30K and ~1.6x10^3 cm-3 in
N159S. These results are compared with the star formation activity. The N159E
clump is associated with embedded cluster(s) as observed at 24 micron and the
derived high temperature is explained as due to the heating by these sources.
The N159E clump is likely responsible for a dark lane in a large HII region by
the dust extinction. The N159W clump is associated with embedded clusters
mainly toward the eastern edge of the clump only. These clusters show offsets
of 20"-40" from the 12CO J=4-3 peak and are probably responsible for heating
indicated by the derived high temperature. The N159W clump exhibits no sign of
star formation toward the 12CO J=4-3 peak position and its western region. We
suggest that the N159W peak represents a pre-star-cluster core of ~105M_sol
which deserves further detailed studies. Note that recent star formation took
place between N159W and N159E as indicated by several star clusters and HII
regions, while the natal molecular gas toward the stars have already been
dissipated by the ionization and stellar winds of the OB stars. The N159S clump
shows little sign of star formation as is consistent with the lower temperature
and somewhat lower density. The N159S clump is also a candidate for future star
formation
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