Ionized helium in prominences and in the chromosphere     

Tadashi Hirayama 《Solar physics》1972,24(2):310-323

Quiescent prominences It is found that Heii 4686 is emitted in the same cold region of 10000 K as hydrogen, metal and neutral helium emission lines. This conclusion is based on the finding that the observed width of 4686 is the same as the calculated width of 4686. The calculated width is derived from the observed widths of hydrogen and metallic lines. The large intensity of Heii 4686 in 10000 K can be explained by the ionization of Heii due to the UV radiation below 228 Å that comes from the corona and the transition region.Loop prominences The very broad width (30 to 50 km s^–1) of 4686 for two post-flare loop prominences shows that the Heii line is emitted in hot regions different from regions of hydrogen and metal emission. From the widths of the Balmer lines and many metallic lines the kinetic temperature for one loop is found to be 16000 K in one part and 7600 K in another part. The electron densities are 10^12.0 cm^–3 and less than 10^11.0 cm^–3 respectively.Chromosphere The intensity of 4686 in the chromosphere can be interpreted in terms of a temperature of 10000 K with the ionization due to UV radiation. But, since observations of the width of 4686 are not available, a definitive conclusion for the chromosphere cannot be reached.  相似文献   

Preliminary observation of missing energy flux of sunspot     

Tadashi Hirayama  Tomizo Okamoto 《Solar physics》1981,73(1):37-43

We have searched for the missing energy flux of the sunspot by measuring white-light photographs over the region around the sunspots exceeding ten times of the diameter of spots. It was found that the excess brightness amounts to 0.3–0.8% of the local continuum intensity immediately beyond the penumbra and smoothly decrease to zero at the edge of our inspected radii of 130 000–160000km. This result suggests that the flux deficit in sunspots of the order of 30% over the umbra-penumbra is roughly the same as the excess flux found in the very large surrounding region which includes photospheric facular contributions. Among nineteen spots fourteen showed this extended bright ring. Narrow band photoelectric scans revealed that the excess radiation originates in the continuum, not from weakened absorption lines.  相似文献   

Sound velocity and density of liquid Ni68S32 under pressure using ultrasonic and X-ray absorption with tomography methods     

Hidenori Terasaki  Keisuke Nishida  Satoru Urakawa  Yusaku Takubo  Soma Kuwabara  Yuta Shimoyama  Kentaro Uesugi  Yoshio Kono  Akihisa Takeuchi  Yoshio Suzuki  Yuji Higo  Tadashi Kondo 《Comptes Rendus Geoscience》2019,351(2-3):163-170

A new experimental setup for simultaneous P-wave velocity (V_P) and density (ρ) measurements for liquid alloys is developed using ultrasonic and X-ray absorption methods combined with X-ray tomography at high pressures and high temperatures. The new setup allows us to directly determine adiabatic bulk moduli (K_S) and to discuss the correlation between the V_P and ρ of the liquid sample. We measured V_P and ρ of liquid Ni₆₈S₃₂ up to 5.6 GPa and 1045 K using this technique. The effect of pressure on the V_P and ρ values of liquid Ni₆₈S₃₂ is similar to that of liquid Fe₅₇S₄₃. (Both compositions correspond to near-eutectic ones.) The obtained K_S values are well fitted to the finite strain equation with a $K_{{\text{S}}_0}$ value (K_S at ambient pressure) of 31.1 GPa and a dK_S/dP value of 8.44. The measured V_P was found to increase linearly with increasing ρ, as approximated by the relationship: V_P [m/s] = 1.29 ρ [kg/m³] – 5726, suggesting that liquid Ni–S follows an empirical linear relationship, Birch's law. The dV_P/dρ slope is similar between Ni₆₈S₃₂ and Fe₅₇S₄₃ liquids, while the V_P–ρ plot of liquid Ni–S is markedly different from that of liquid Fe–S, which indicates that the effect of Ni on Birch's law is important for understanding the V_P–ρ relation of planetary and Moon's molten cores.  相似文献   

The Kellwasser events in the Upper Devonian Frasnian to Famennian transition in the Toc Tat Formation,northern Vietnam     

Toshifumi Komatsu  Ryota Urakawa  Toshitaka Inada  Kazuki Yamauchi  Takumi Maekawa  Reishi Takashima  Mark Williams  Phong D. Nguyen  Hung D. Doan  Minh T. Nguyen  Shuji Niko  Gengo Tanaka  Tatsuhiko Yamaguchi 《Island Arc》2019,28(1)

Upper Devonian carbonates of the Toc Tat Formation in the Si Phai Pass area of Dong Van District, northern Vietnam were deposited in carbonate platform, slope, and basin environments. These carbonates yield abundant conodonts indicative of the Palmatolepis nasuta, Pa. linguiformis and Pa. triangularis zones, the Frasnian–Famennian stage boundary being identified by the first occurrence of Pa. triangularis. Two positive carbon isotope excursions are recognized, the lower excursion peaking in the interval of the lower to middle Pa. nasuta Zone, whilst the upper excursion peaks just above the local Frasnian–Famennian boundary. Based on the biostratigraphy, these excursions equate to the Lower and Upper Kellwasser events. Locally, tentaculitoid taxa (Nowakia, Styliolina, Homoctenus, and Metastyliolina?) are abundant in the interval of the Pa. nasuta Zone, but show a drastic decline in abundance before the Lower Kellwasser Event, and only two taxa survived into the Famennian.  相似文献   

A Late Cretaceous mammalian dentary from the Ashizawa Formation (Futaba Group), Fukushima,northeastern Japan          下载免费PDF全文

Nao Kusuhashi  Tadashi Suzuki  Kazuaki Terui  Atsushi Sato  Romain Amiot 《Island Arc》2016,25(6):403-409

A mammalian dentary discovered in the Coniacian Ashizawa Formation (Fukushima, northeastern Japan) is described. The specimen is a fragment of the horizontal ramus of a left edentulous dentary with five alveoli, the distal four of which are plugged with broken roots. Based on the morphologies of the dentary and the roots, it is considered to be of a therian mammal. This constitutes the first discovery of a Mesozoic mammal in northeastern Japan and highlights the potential for future mammal discoveries in the Cretaceous System in northeastern Japan, which will be significant for disclosure of the mammalian faunal evolution in East Asia during the Late Cretaceous.  相似文献   

Groundwater and surface water interactions in an alluvial plain, Tuul River Basin, Ulaanbaatar, Mongolia     

Maki Tsujimur  Koichi Ike  Tadashi Tanak  Lunten Janchivdorj  BadamgaravErdenchimeg  Damdinbazar Unurjargal  Ramasamy Jayakumar 《寒旱区科学》2013,5(1):0126-0132

Drinking water supplies in Ulaanbaatar, the capital of Mongolia, are completely dependent on groundwater sourced from pumping wells located in an alluvial plain of the Tuul River which flows through Ulaanbaatar. The interaction between groundwater in the alluvial plain and river surface water was investigated using a hydrological and multi-tracers approach. The observed groundwater contour map clearly shows that the Tuul River recharges the floodplain groundwater and groundwater flows from east to west. The similarity of chemical and stable isotopic compositions suggests that groundwater is mainly recharged by Tuul River water in the vicinity of the river. In addition, considering groundwater contours and chemical composition, groundwater in the northern and southern mountain sides contribute to floodplain groundwater. Stable isotopic information suggests that winter season precipitation also contributes to the groundwater, because groundwater in a specific region has a considerably lower isotopic ratio. Using the End Member Mixing Analysis applying oxygen-18, SiO₂ and HCO₃ ^- as tracers, the contribution ratios of the Tuul River, groundwater in the northern and southern mountain regions, and winter season precipitation to floodplain groundwater are estimated to be 58% to 85%, 1% to 54%, 0% to 16%, and 0% to 12%, respectively.  相似文献   

Analytical direct planetary perturbations on the orbital motion of satellites     

Julien Frouard  Tadashi Yokoyama 《Celestial Mechanics and Dynamical Astronomy》2013,115(1):59-79

An analytical expansion of the disturbing function arising from direct planetary perturbations on the motion of satellites is derived. As a Fourier series, it allows the investigation of the secular effects of these direct perturbations, as well as of every argument present in the perturbation. In particular, we construct an analytical model describing the evection resonance between the longitude of pericenter of the satellite orbit and the longitude of a planet, and study briefly its dynamic. The expansion developed in this paper is valid in the case of planar and circular planetary orbits, but not limited in eccentricity or inclination of the satellite orbit.  相似文献   

Influences of channelization on discharge of suspended sediment and wetland vegetation in Kushiro Marsh, northern Japan     

Futoshi Nakamura  Tadashi Sudo  Satoshi Kameyama  Mieko Jitsu 《Geomorphology》1997,18(3-4)

The effects of wetlands on hydrology, water quality, and wildlife habitat are internationally recognized. Protecting the remaining wetlands is one of the most important environmental issues in many countries. However wetlands in Japan have been gradually shrinking due to agricultural development and urbanization, which generally lowers the groundwater level and introduces suspended sediment and sediment-associated nutrients into wetlands. We examined the influences of channelization on discharge of suspended sediment and wetland vegetation in Hokkaido, northern Japan. The impact of river channelization was confirmed not only by the sediment budgets but also by river aggradation or degradation after the channelization and by the resultant vegetational changes. The budgets of suspended sediment demonstrated that wash load was the predominant component accounting for 95% of the total suspended load delivered into the wetland. This suspended sediment was primarily transported into the wetland by flooding associated with heavy rainfall. Twenty-three percent of the wash load and 63% of the suspended bed material load were deposited in the channelized reach, which produced aggradation of about 2 m at the end of the reach. A shorting of the length of the channel, due to channelization of a meandering river, steepened the slope and enhanced the stream power to transport sediment. This steepening shifted the depositional zones of fine sediment 5 km downstream and aggraded the riverbed. Development of the watershed may increase not only the water discharge but also the amount of suspended sediments. The aggradation reduced the carrying capacity of the channel and caused sediment ladened water to flood over the wetlands. The fine sediment accumulated on the wetlands gradually altered the edaphic conditions and wetland vegetation. A low percentage (10 to 15%) of organic contents of wetlands' soil is more evidence indicating that the present condition is far different from normal. Original vegetation such as sedges and Alnus japonica were disappearing from the adjacent areas of the river channel and were being replaced by willow trees (Salix spp.).  相似文献   

Storm runoff processes in a small forested drainage basin     

Tadashi Tanaka 《Environmental Geology》1992,19(3):179-191

A brief review was made of storm runoff processes and the mechanisms of its generation in relation to subsurface water behaviors in a small forested drainage basin located in the western suburbs of Tokyo, Japan. The results of field investigations showed that the main source of storm runoff was groundwater flow and that the rapid and large amounts of groundwater discharge during a storm event could not be explained solely by the traditional concept of Darcian matrix flow. Several mechanisms such as pipe flow, air pressure effect, and capillary barrier effect were recognized that would induce a rapid response of groundwater to storm events depending on differences in local hydrologic conditions. All of these mechanisms were chiefly attributed to inhomogeneities of the soil deposits. The importance of dynamic behaviors of subsurface water during a storm event was emphasized in considering the mechanism of storm runoff generation.  相似文献   

Sound velocity and elastic properties of Fe–Ni and Fe–Ni–C liquids at high pressure     

Soma Kuwabara  Hidenori Terasaki  Keisuke Nishida  Yuta Shimoyama  Yusaku Takubo  Yuji Higo  Yuki Shibazaki  Satoru Urakawa  Kentaro Uesugi  Akihisa Takeuchi  Tadashi Kondo 《Physics and Chemistry of Minerals》2016,43(3):229-236

The sound velocity (V _P) of liquid Fe–10 wt% Ni and Fe–10 wt% Ni–4 wt% C up to 6.6 GPa was studied using the ultrasonic pulse-echo method combined with synchrotron X-ray techniques. The obtained V _P of liquid Fe–Ni is insensitive to temperature, whereas that of liquid Fe–Ni–C tends to decrease with increasing temperature. The V _P values of both liquid Fe–Ni and Fe–Ni–C increase with pressure. Alloying with 10 wt% of Ni slightly reduces the V _P of liquid Fe, whereas alloying with C is likely to increase the V _P. However, a difference in V _P between liquid Fe–Ni and Fe–Ni–C becomes to be smaller at higher temperature. By fitting the measured V _P data with the Murnaghan equation of state, the adiabatic bulk modulus (K _S0) and its pressure derivative (K _S ^′ ) were obtained to be K _S0 = 103 GPa and K _S ^′  = 5.7 for liquid Fe–Ni and K _S0 = 110 GPa and K _S ^′  = 7.6 for liquid Fe–Ni–C. The calculated density of liquid Fe–Ni–C using the obtained elastic parameters was consistent with the density values measured directly using the X-ray computed tomography technique. In the relation between the density (ρ) and sound velocity (V _P) at 5 GPa (the lunar core condition), it was found that the effect of alloying Fe with Ni was that ρ increased mildly and V _P decreased, whereas the effect of C dissolution was to decrease ρ but increase V _P. In contrast, alloying with S significantly reduces both ρ and V _P. Therefore, the effects of light elements (C and S) and Ni on the ρ and V _P of liquid Fe are quite different under the lunar core conditions, providing a clue to constrain the light element in the lunar core by comparing with lunar seismic data.  相似文献