Ionization States and Plasma Structures of Mixed-morphology SNRs Observed with ASCA

We present the results of a systematic study using ASCA of the ionization state for six ``mixed-morphology'' supernova emnants (MMSNRs): IC 443, W49B, W28, W44, 3C391, and Kes 27. MMSNRs show centrally filled thermal X-ray emission, which contrasts to shell-like radio morphology, a set of haracteristics at odds with the standard model of SNR evolution (e.g., the Sedov model). We have therefore studied the evolution of the MMSNRs from the ionization conditions inferred from the X-ray spectra, independent of X-ray morphology. We find highly ionized plasmas approaching ionization equilibrium in all the mmsnrs. The degree of ionization is systematically higher than the plasma usually seen in shell-like SNRs. Radial temperature gradients are also observed in five remnants, with cooler plasma toward the limb. In IC 443 and W49B, we find a plasma structure consistent with shell-like SNRs, suggesting that at least some MMSNRs have experienced similar evolution to shell-like SNRs. In addition to the results above, we have discovered an ``overionized'' ionization state in W49B, in addition to that previously found in IC 443. Thermal conduction can cause the hot interior plasma to become overionized by reducing the temperature and density gradients, leading to an interior density increase and temperature decrease. Therefore, we suggest that the ``center-filled'' X-ray morphology develops as the result of thermal conduction, and should arise in all SNRs. This is consistent with the results that MMSNRs are near collisional ionization equilibrium since the conduction timescale is roughly similar to the ionization timescale. Hence, we conclude that MMSNRs are those that have evolved over$\sim10^4$ yr. We call this phase as the ``conduction phase.''Comment: 34 pages, 20 figures, 9 tables, accepted for publication in The Astrophysical Journa

Chandra X-ray Observation of a Mature Cloud-Shock Interaction in the Bright Eastern Knot Region of Puppis A

We present Chandra X-ray images and spectra of the most prominent cloud-shock interaction region in the Puppis A supernova remnant. The Bright Eastern Knot (BEK) has two main morphological components: (1) a bright compact knot that lies directly behind the apex of an indentation in the eastern X-ray boundary and (2) lying 1' westward behind the shock, a curved vertical structure (bar) that is separated from a smaller bright cloud (cap) by faint diffuse emission. Based on hardness images and spectra, we identify the bar and cap as a single shocked interstellar cloud. Its morphology strongly resembles the ``voided sphere'' structures seen at late times in Klein et al.'s experimental simulations of cloud-shock interactions, when the crushing of the cloud by shear instabilities is well underway. We infer an interaction time of roughly 3 cloud-crushing timescales, which translates to 2000-4000 years, based on the X-ray temperature, physical size, and estimated expansion of the shocked cloud. This is the first X-ray identified example of a cloud-shock interaction in this advanced phase. Closer to the shock front, the X-ray emission of the compact knot in the eastern part of the BEK region implies a recent interaction with relatively denser gas, some of which lies in front of the remnant. The complex spatial relationship of the X-ray emission of the compact knot to optical [O III] emission suggests that there are multiple cloud interactions occurring along the line of sight.Comment: 22 pages LaTeX with multiple figures, to appear in Ap

The Radial Structure of the Cygnus Loop Supernova Remnant --- Possible evidence of a cavity explosion ---

We observed the North-East (NE) Limb toward the center region of the Cygnus Loop with the ASCA Observatory. We found a radial variation of electron temperature (kTe) and ionization timescale (log(\tau)) whereas no variation could be found for the abundances of heavy elements. In this paper, we re-analyzed the same data set and new observations with the latest calibration files. Then we constructed the precise spatial variations of kTe, log(\tau), and abundances of O, Ne, Mg, Si, and Fe over the field of view (FOV). We found a spatial variation not only in kTe and in log(\tau) but also in most of heavy elements. As described in Miyata et al. (1994), values of kTe increase and those of log(\tau) decrease toward the inner region. We found that the abundance of heavy elements increases toward the inner region. The radial profiles of O, Ne, and Fe show clear jump structures at a radius of 0.9 Rs, where Rs is the shock radius. Outside of 0.9 Rs, abundances of all elements are constant. On the contrary, inside of 0.9 Rs, abundances of these elements are 20--30 % larger than those obtained outside of 0.9 Rs. The radial profile of kTe also shows the jump structure at 0.9 Rs. This means that the hot and metal rich plasma fills the volume inside of 0.9 Rs. We concluded that this jump structure was the possible evidence for the pre-existing cavity produced by the precursor. If the ejecta fills inside of 0.9 Rs, the total mass of the ejecta was roughly 4\Msun. We then estimated the main-sequence mass to be roughly 15\Msun, which supports the massive star in origin of the Cygnus Loop supernova remnant and the existence of a pre-existing cavity.Comment: 37 pages, 14 figures. Accepted for publication of Ap

Training for Safehandling of Radiation and Radioisotopes and X-ray Machines for Beginners in Tohoku Unlversity

開始ページ、終了ページ: 冊子体のページ付

Training for Safehandling of Radiation and Radioisotopes and X-Ray Machines for Beginners in Tohoku University

開始ページ、終了ページ: 冊子体のページ付

Training for Safehandling of Radiation and Radioisotopes and X-ray Machines for Beginners in Tohoku University

開始ページ、終了ページ: 冊子体のページ付

Training for Safehandling of Radiation and Radioisotopes and X-ray Machines for Beginners in Tohoku University

開始ページ、終了ページ: 冊子体のページ付

Industrial Resources: Hopkins County - Dawson Springs

Resources for Economic Development: Dawson Springs, [Kentucky] prepared by the Kentucky Cabinet for Economic Development Division of Research in cooperation with West Hopkins Industries, Inc. and the city of Dawson Springs, 1996. The report includes, but is not limited to, information about: population, market, local manufacturing, transportation, utilities, fuel, water, sewage, industrial sites, local, government and services, taxes, educational and health facilities, housing, communication, recreation, natural resources, markets, and climate

Ultrahigh magnetic field spectroscopy reveals the band structure of the 3D topological insulator Bi2_2Se3_3

We have investigated the band structure at the $\Gamma$ point of the three-dimensional (3D) topological insulator Bi$_2$Se$_3$ using magneto-spectroscopy over a wide range of energies ($0.55-2.2$\,eV) and in ultrahigh magnetic fields up to 150\,T. At such high energies ($E>0.6$\,eV) the parabolic approximation for the massive Dirac fermions breaks down and the Landau level dispersion becomes nonlinear. At even higher energies around 0.99 and 1.6 eV, new additional strong absorptions are observed with a temperature and magnetic-field dependence which suggest that they originate from higher band gaps. Spin orbit splittings for the further lying conduction and valence bands are found to be 0.196 and 0.264 eV

Experimental analysis of vacuum pressure and gas flow rate in structured-core transparent vacuum insulation panels

The notion that modern buildings should strive to be net-zero energy buildings (NZEBs) is widely accepted. One of the causes leading to high energy usage for space heating, resulting in avoidable carbon emissions, is heat loss via building windows. In order to improve window’s insulation in existing buildings, structured-core transparent vacuum insulation panels (TVIPs) are proposed. TVIPs mainly consist of the structured core material, the low-emissivity film, and the transparent gas barrier envelope. TVIPs have high insulation performance and are inexpensive to manufacture and can be easily installed. Therefore, TVIPs have the potential to improve window’s insulation in existing buildings at a low cost. However, it is necessary to overcome the issue of preventing the pressure rise inside TVIP after vacuum sealing. The authors constructed an experimental setup to quantify the effect of reduction of gas flow rate in TVIP after evacuation by applying the pressure-rate-of-rise-method. In this experiment, a gas barrier film with a straw was used as the vacuum chamber. This could reproduce the pressure increase in the TVIP after sealing and the gas flow rate in the TVIP is evaluated. The experimental result shows that the coated core material and the enclosing getter agent lowered the pressure rise and gas flow rate in TVIP by combining concurrent evacuation and heating. Furthermore, after extending the simultaneous vacuuming and heating period to 8 h and applying the coated core material, and enclosing the getter agent, the internal pressure in TVIP may be lowered to around 1 Pa after 30 min after halting vacuuming. It was confirmed that this pressure satisfied the performance required for TVIPs, and the result was much closer to the realization of TVIPs