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1.
Stabilities of hexagonal new aluminous (NAL) phase and Ca-ferrite-type (CF) phase were investigated on the join NaAlSiO4-MgAl2O4 in a pressure range from 23 to 58 GPa at approximately constant temperature of 1,850 K, on the basis of in situ synchrotron
X-ray diffraction measurements in a laser-heated diamond-anvil cell. The results show that NAL is formed as a single phase
up to 34 GPa, NAL + CF between 34 and 43 GPa, and only CF at higher pressures in 40%NaAlSiO4-60%MgAl2O4 bulk composition. On the other hand, both NAL and CF coexist below 38 and 36 GPa, and only CF was obtained at higher pressures
in 60%NaAlSiO4-40%MgAl2O4 and 20%NaAlSiO4-80%MgAl2O4 composition, respectively. These results indicate that NAL appears only up to 46 GPa at 1,850 K, and CF forms continuous
solid solution at higher pressures on the join NaAlSiO4-MgAl2O4. NAL has limited stability in subducted mid-oceanic ridge basalt crust in the Earth’s lower mantle and undergoes a phase
transition to CF in deeper levels. 相似文献
2.
Formation of a Flare-Productive Active Region: Observation and Numerical Simulation of NOAA AR 11158
We present a comparison of the Solar Dynamics Observatory (SDO) analysis of NOAA Active Region (AR) 11158 and numerical simulations of flux-tube emergence, aiming to investigate the formation process of this flare-productive AR. First, we use SDO/Helioseismic and Magnetic Imager (HMI) magnetograms to investigate the photospheric evolution and Atmospheric Imaging Assembly (AIA) data to analyze the relevant coronal structures. Key features of this quadrupolar region are a long sheared polarity inversion line (PIL) in the central δ-sunspots and a coronal arcade above the PIL. We find that these features are responsible for the production of intense flares, including an X2.2-class event. Based on the observations, we then propose two possible models for the creation of AR 11158 and conduct flux-emergence simulations of the two cases to reproduce this AR. Case 1 is the emergence of a single flux tube, which is split into two in the convection zone and emerges at two locations, while Case 2 is the emergence of two isolated but neighboring tubes. We find that, in Case 1, a sheared PIL and a coronal arcade are created in the middle of the region, which agrees with the AR 11158 observation. However, Case 2 never builds a clear PIL, which deviates from the observation. Therefore, we conclude that the flare-productive AR 11158 is, between the two cases, more likely to be created from a single split emerging flux than from two independent flux bundles. 相似文献
3.
We find clear evidence for typical chromospheric evaporation associated with small transient brightenings, using the data from the X-ray Telescope (XRT) onboard Hinode. We found 13 events, each having a pair of evaporation upflows arising almost symmetrically from both foot points of a magnetic loop. These facts strongly support the standard flare model based on the magnetic reconnection. The apparent upflow velocities of three of the events are ≈?500?km?s?1, while those of the other events are ≈?100?km?s?1. This is the first clear direct detection of evaporating upflow motion in soft X-ray images from Hinode/XRT; such images were obtained with high cadence (≈?60?s) and high spatial resolution (1?arcsec). 相似文献
4.
Saori Imada Kei Hirose Tetsuya Komabayashi Toshihiro Suzuki Yasuo Ohishi 《Physics and Chemistry of Minerals》2012,39(7):525-530
Compression behaviors of two Al-rich phases in the lower mantle, hexagonal new aluminum-rich (NAL) phase and its high-pressure polymorph Ca-ferrite-type (CF) phase, were examined for identical Na0.4Mg0.6Al1.6Si0.4O4 (40?% NaAlSiO4–60?% MgAl2O4) composition. The volumes of the NAL and CF phases were obtained at room temperature up to 31 and 134?GPa, respectively, by a combination of laser-annealed diamond-anvil cell techniques and synchrotron X-ray diffraction measurements. Fitting of the third-order Birch–Murnaghan equation of state to such pressure–volume data yields bulk modulus K 0?=?199(6) GPa at 1?bar and its pressure derivative K 0′?=?5.0(6) for the NAL phase and K 0?=?169(5) GPa and K 0′?=?6.3(3) for the CF phase. These results indicate that the bulk modulus increases from 397 to 407 GPa across the phase transition from the NAL to CF phase at 43 GPa, where the NAL phase completely transforms into the CF phase on Na0.4Mg0.6Al1.6Si0.4O4. Density also increases by 2.1?% across the phase transition. 相似文献
5.
To obtain the basic information required before using Populus alba L. to phytoremediate degraded saline environments, we investigated the effects of saline irrigation on the growth, survival, Na partitioning, and Na dynamics of 1-year-old rooted cuttings. The plants were grown in a greenhouse in lysimeters containing sandy soil and were watered with field water (control) or solutions containing either 2000 or 5000 mg L?1 of a mixture of NaCl and CaCl2 (low- and high-salt treatments, respectively). All plants in the control and the low-salt treatment survived after 1 year of treatment, but the high-salt treatment significantly decreased growth and caused 20% mortality. Strong Na partitioning was observed in the roots in all three treatments, suggesting that this is an important salt tolerance mechanism in P. alba. Total Na uptake was similar in the low-salt and high-salt treatments, and was about 3 times the value in the control. However, the compartmentalization of Na in fallen leaves, dead leaves and dead branches in the high-salt treatment was about twice the level in the low-salt treatment. The plants accumulate Na under moderate levels of salinity, suggesting that P. alba is a good candidate for phytoremediating salinized soil. 相似文献
6.
K. Wilhelm L. Abbo F. Auch��re N. Barbey L. Feng A. H. Gabriel S. Giordano S. Imada A. Llebaria W. H. Matthaeus G. Poletto N.-E. Raouafi S. T. Suess L. Teriaca Y.-M. Wang 《Astronomy and Astrophysics Review》2011,19(1):1-70
Coronal plumes, which extend from solar coronal holes (CH) into the high corona and??possibly??into the solar wind (SW), can now continuously be studied with modern telescopes and spectrometers on spacecraft, in addition to investigations from the ground, in particular, during total eclipses. Despite the large amount of data available on these prominent features and related phenomena, many questions remained unanswered as to their generation and relative contributions to the high-speed streams emanating from CHs. An understanding of the processes of plume formation and evolution requires a better knowledge of the physical conditions at the base of CHs, in plumes and in the surrounding inter-plume regions. More specifically, information is needed on the magnetic field configuration, the electron densities and temperatures, effective ion temperatures, non-thermal motions, plume cross sections relative to the size of a CH, the plasma bulk speeds, as well as any plume signatures in the SW. In spring 2007, the authors proposed a study on ??Structure and dynamics of coronal plumes and inter-plume regions in solar coronal holes?? to the International Space Science Institute (ISSI) in Bern to clarify some of these aspects by considering relevant observations and the extensive literature. This review summarizes the results and conclusions of the study. Stereoscopic observations allowed us to include three-dimensional reconstructions of plumes. Multi-instrument investigations carried out during several campaigns led to progress in some areas, such as plasma densities, temperatures, plume structure and the relation to other solar phenomena, but not all questions could be answered concerning the details of plume generation process(es) and interaction with the SW. 相似文献
7.
Hayakawa Hisashi Sôma Mitsuru Tanikawa Kiyotaka Willis David M. Wild Matthew N. Macdonald Lee T. Imada Shinsuke Hattori Kentaro Richard Stephenson F. 《Solar physics》2019,294(9):1-13
Solar Physics - Large sunspots can be observed with the unaided eye under suitable atmospheric seeing conditions. Such observations are of particular value because the frequency of their appearance... 相似文献
8.
L. K. Harra C. H. Mandrini S. Dasso A. M. Gulisano K. Steed S. Imada 《Solar physics》2011,268(1):213-230
For large eruptions on the Sun, it is often a problem that the core dimming region cannot be observed due to the bright emission
from the flare itself. However, spectroscopic data can provide the missing information through the measurement of Doppler
velocities. In this paper we analyse the well-studied flare and coronal mass ejection that erupted on the Sun on 13 December
2006 and reached the Earth on 14 December 2006. In this example, although the imaging data were saturated at the flare site
itself, by using velocity measurements we could extract information on the core dimming region, as well as on remote dimmings.
The purpose of this paper is to determine more accurately the magnetic flux of the solar source region, potentially involved
in the ejection, through a new technique. The results of its application are compared to the flux in the magnetic cloud observed
at 1 AU, as a way to check the reliability of this technique. We analysed data from the Hinode EUV Imaging Spectrometer to estimate the Doppler velocity in the active region and its surroundings before and after the
event. This allowed us to determine a Doppler velocity ‘difference’ image. We used the velocity difference image overlayed
on a Michelson Doppler Imager magnetogram to identify the regions in which the blue shifts were more prominent after the event;
the magnetic flux in these regions was used as a proxy for the ejected flux and compared to the magnetic cloud flux. This
new method provides a more accurate flux determination in the solar source region. 相似文献
9.
E. P. Pavlenko T. Kato O. I. Antonyuk A. Imada R. Ishioka H. Maehara 《Astrophysics》2011,54(4):483-495
Results are presented from photometric studies of the dwarf nova V1108 Her conducted at the primary focus of the 2.6-m G.
A. Shajn Telescope at the Crimean Astrophysical Observatory during June-July 2008, 4 years after the 2004 outburst. An orbital
period of 0.05672(4) days is found for the system. An analysis of observations made earlier during the 2004 outburst reveals
an orbital signal which indicates that V1108 Her is an eclipsing system. The mass ratio of the secondary component to the
white dwarf is estimated to be q = 0.068, which makes it highly likely that the secondary component of this system is a brown dwarf. The orbital light curves
indicate a complex structure for the accretion disk whose radius has reached a 2:1 resonance. An explanation is suggested
for a quasi-periodic modulation in the brightness at 1/4 of the orbital period observed in V1108 Her and other WZ Sge systems. 相似文献
10.