320 research outputs found
Formation of Galactic Center Magnetic Loops
A survey for the molecular clouds in the Galaxy with NANTEN mm telescope has
discovered molecular loops in the Galactic center region. The loops show
monotonic gradients of the line of sight velocity along the loops and the large
velocity dispersions towards their foot points. It is suggested that these
loops are explained in terms of the buoyant rise of magnetic loops due to the
Parker instability. We have carried out global three-dimensional
magneto-hydrodynamic simulations of the gas disk in the Galactic center. The
gravitational potential is approximated by the axisymmetric potential proposed
by Miyamoto & Nagai (1975). At the initial state, we assume a warm (~ 10^4 K)
gas torus threaded by azimuthal magnetic fields. Self-gravity and radiative
cooling of the gas are ignored. We found that buoyantly rising magnetic loops
are formed above the differentially rotating, magnetically turbulent disk. By
analyzing the results of global MHD simulations, we have identified individual
loops, about 180 in the upper half of the disk, and studied their statistical
properties such as their length, width, height, and velocity distributions
along the loops. Typical length and height of a loop are 1kpc and 200pc,
respectively. The line of sight velocity changes linearly along a loop and
shows large dispersions around the foot-points. Numerical results indicate that
loops emerge preferentially from the region where magnetic pressure is large.
We argue that these properties are consistent with those of the molecular loops
discovered by NANTEN.Comment: 16pages, 10figures. Accepted for publication in PASJ. Replace to
higher resolution versio
NPR Hair Modeling with Parametric Clumps
This paper presents a modeling method for NPR hair composed of parametric 3D clumps. The clump parameters are not only for modifying a single clump but also for modifying all or large part of clumps similarly and simultaneously, and then a user can create a hairstyle only by adjusting the parameters. Our experiments show that even naive users can model a variety of hairstyles with little effort.2017 International Conference on Cyberworlds CW 2017, 20-22 September, 2017, Chester, United Kingdo
Color2Hatch: conversion of color to hatching for low-cost printing
In this paper, we propose Color2Hatch, a decolorization method for business/presentation graphics. In Color2Hatch, each region represented as a closed path and uniformly colored in scalable vector graphics (SVG) is converted to a region hatched in black and white. From the characteristics of business graphics, the hatching patterns are designed to represent mainly the hue in the region; additionally, lightness and saturation can also be reflected. To discriminate subtle differences between colors, attached short line segments, zigzag lines, and wave lines are used in hatching by analogy to a clock. Compared with the existing decolorization methods, for example, grayscale conversion and texturing, our method is superior in the discrimination of regions, suitable for low-cost black and white printing that meets real-world needs
Evaluation of left atrial appendage flow in patients with atrial fibrillation: A transesophageal echocardiography study with intravenous albumin-contrast agent
Discovery of Molecular Loop 3 in the Galactic Center: Evidence for a Positive-Velocity Magnetically Floated Loop towards
We have discovered a molecular dome-like feature towards and . The large velocity
dispersions of 50--100 km s of this feature are much larger than those
in the Galactic disk and indicate that the feature is located in the Galactic
center, probably within kpc of Sgr A. The distribution has a
projected length of pc and height of pc from the Galactic
disk and shows a large-scale monotonic velocity gradient of km s
per pc. The feature is also associated with HI gas having a
more continuous spatial and velocity distribution than that of CO. We
interpret the feature as a magnetically floated loop similar to loops 1 and 2
and name it "loop 3". Loop 3 is similar to loops 1 and 2 in its height and
length but is different from loops 1 and 2 in that the inner part of loop 3 is
filled with molecular emission. We have identified two foot points at the both
ends of loop 3. HI, CO and CO datasets were used to estimate the
total mass and kinetic energy of loop 3 to be \sim3.0 \times 10^{6} \Mo and
ergs. The huge size, velocity dispersions and energy
are consistent with the magnetic origin the Parker instability as in case of
loops 1 and 2 but is difficult to be explained by multiple stellar explosions.
We argue that loop 3 is in an earlier evolutionary phase than loops 1 and 2
based on the inner-filled morphology and the relative weakness of the foot
points. This discovery indicates that the western part of the nuclear gas disk
of kpc radius is dominated by the three well-developed magnetically
floated loops and suggests that the dynamics of the nuclear gas disk is
strongly affected by the magnetic instabilities.Comment: 30 pages, 10 figures. High resolution figures are available at
http://www.a.phys.nagoya-u.ac.jp/~motosuji/fujishita09_figs
A Detailed Observational Study of Molecular Loops 1 and 2 in the Galactic Center
Fukui et al. (2006) discovered two huge molecular loops in the Galactic
center located in (l, b) ~ (355 deg-359 deg, 0 deg-2 deg) in a large velocity
range of -180-40 km s^-1. Following the discovery, we present detailed
observational properties of the two loops based on NANTEN 12CO(J=1-0) and
13CO(J=1-0) datasets at 10 pc resolution including a complete set of velocity
channel distributions and comparisons with HI and dust emissions as well as
with the other broad molecular features. We find new features on smaller scales
in the loops including helical distributions in the loop tops and vertical
spurs. The loops have counterparts of the HI gas indicating that the loops
include atomic gas. The IRAS far infrared emission is also associated with the
loops and was used to derive an X-factor of 0.7(+/-0.1){\times}10^20 cm^-2 (K
km s^-1)^-1 to convert the 12CO intensity into the total molecular hydrogen
column density. From the 12CO, 13CO, H I and dust datasets we estimated the
total mass of loops 1 and 2 to be ~1.4 {\times} 106 Msun and ~1.9 {\times} 10^6
Msun, respectively, where the H I mass corresponds to ~10-20% of the total mass
and the total kinetic energy of the two loops to be ~10^52 ergs. An analysis of
the kinematics of the loops yields that the loops are rotating at ~47 km s-1
and expanding at ~141 km s^-1 at a radius of 670 pc from the center. Fukui et
al. (2006) presented a model that the loops are created by the magnetic
flotation due to the Parker instability with an estimated magnetic field
strength of ~150 {\mu}G. We present comparisons with the recent numerical
simulations of the magnetized nuclear disk by Machida et al. (2009) and
Takahashi et al. (2009) and show that the theoretical results are in good
agreements with the observations. The helical distributions also suggest that
some magnetic instability plays a role similarly to the solar helical features.Comment: 40 pages, 22 figures, submitted to publication in PAS
Similarity between the Molecular Loops in the Galactic Center and the Solar Chromospheric Arch Filaments
We carried out two-dimensional magnetohydrodynamic simulations of the
Galactic gas disk to show that the dense loop-like structures discovered by the
Galactic center molecular cloud survey by NANTEN 4 m telescope can be formed by
the buoyant rise of magnetic loops due to the Parker instability. At the
initial state, we assumed a gravitationally stratified disk consisting of the
cool layer ( K), warm layer ( K), and hot layer ( K). Simulation box is a local part of the disk containing the
equatorial plane. The gravitational field is approximated by that of a point
mass at the galactic center. The self-gravity, and the effects of the galactic
rotation are ignored. Numerical results indicate that the length of the
magnetic loops emerging from the disk is determined by the scale height of the
hot layer ( 100 pc at 1 kpc from the Galactic center). The loop length,
velocity gradient along the loops and large velocity dispersions at their foot
points are consistent with the NANTEN observations. We also show that the loops
become top-heavy when the curvature of the loop is sufficiently small, so that
the rising loop accumulates the overlying gas faster than sliding it down along
the loop. This mechanism is similar to that of the formation of solar
chromospheric arch filaments. The molecular loops emerge from the low
temperature layer just like the dark filaments observed in the H image
of the emerging flux region of the sun.Comment: 23 pages, 13 figures. Accepted for publication in PAS
Development of a shutterless continuous rotation method using an X-ray CMOS detector for protein crystallography
A shutterless continuous rotation method using an X-ray complementary metal-oxide semiconductor (CMOS) detector has been developed for high-speed, precise data collection in protein crystallography. The new method and detector were applied to the structure determination of three proteins by multi- and single-wavelength anomalous diffraction phasing and have thereby been proved to be applicable in protein crystallography
- …