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51.
52.
Jagdish Chandra Gupta 《Earth, Moon, and Planets》1975,14(2):247-253
In analyses of the effect of variation of the Earth-Moon distance on geophysical phenomena, it is customary to arrange the geophysical data according to the dates of apogee and perigee. However, lunar distances at apogee and especially at perigee vary within wide limits from month to month. A new daily indexD' of lunar distance is defined to permit a more precise determination of effects related to lunar distance. It is readily calculated by a computer program. 相似文献
53.
Radiative recombination coefficients for some quadruply and quintuply ionized atoms, present in the Sun and its atmosphere, are investigated in the temperature range 10–104 K by using the method of detailed balance. Simple expressions are given for a quick estimation. 相似文献
54.
Suresh Chandra 《Astrophysics and Space Science》1983,96(2):455-456
The investigation of Alamet al. (1979), of the temperature distribution in spherically-symmetric transition region and inner corona, appears to be in error. 相似文献
55.
56.
Navin Chandra Joshi Neeraj Singh Bankoti Seema Pande Bimal Pande Kavita Pandey 《Solar physics》2009,260(2):451-463
In this article we present the results of a study of the spatial distribution and asymmetry of solar active prominences (SAP)
for the period 1996 through 2007 (solar cycle 23). For more meaningful statistical analysis we analyzed the distribution and
asymmetry of SAP in two subdivisions viz. Group1 (ADF, APR, DSF, CRN, CAP) and Group2 (AFS, ASR, BSD, BSL, DSD, SPY, LPS). The North – South (N – S) latitudinal distribution
shows that the SAP events are most prolific in the 21° to 30° slice in the Northern and Southern Hemispheres; the East – West
(E – W) longitudinal distribution study shows that the SAP events are most prolific (best observable) in the 81° to 90° slice
in the Eastern and Western Hemispheres. It was found that the SAP activity during this cycle is low compared to previous solar
cycles. The present study indicates that during the rising phase of the cycle the number of SAP events are roughly equal in
the Northern and Southern Hemispheres. However, activity in the Southern Hemisphere has been dominant since 1999. Our statistical
study shows that the N – S asymmetry is more significant then the E – W asymmetry. 相似文献
57.
A filament disappearance event was observed on 22 May 2008 during our recent campaign JOP 178. The filament, situated in the Southern Hemisphere, showed sinistral chirality consistent with the hemispheric rule. The event was well observed by several observatories, in particular by THEMIS. One day, before the disappearance, Hα observations showed up- and down-flows in adjacent locations along the filament, which suggest plasma motions along twisted flux rope. THEMIS and GONG observations show shearing photospheric motions leading to magnetic flux canceling around barbs. STEREO A, B spacecraft with separation angle 52.4°, showed quite different views of this untwisting flux rope in He ii 304 Å images. Here, we reconstruct the three-dimensional geometry of the filament during its eruption phase using STEREO EUV He ii 304 Å images and find that the filament was highly inclined to the solar normal. The He ii 304 Å movies show individual threads, which oscillate and rise to an altitude of about 120 Mm with apparent velocities of about 100 km?s?1 during the rapid evolution phase. Finally, as the flux rope expands into the corona, the filament disappears by becoming optically thin to undetectable levels. No CME was detected by STEREO, only a faint CME was recorded by LASCO at the beginning of the disappearance phase at 02:00 UT, which could be due to partial filament eruption. Further, STEREO Fe xii 195 Å images showed bright loops beneath the filament prior to the disappearance phase, suggesting magnetic reconnection below the flux rope. 相似文献
58.
Using the Quantum hydrodynamic (QHD) model the modulational instability of electron-acoustic waves (EAWs) has been examined theoretically by deriving a nonlinear Schrodinger equation in a two-electron-populated relativistically degenerate super dense plasma. Through numerical analysis it is shown that the relativistic degeneracy parameter significantly influence the stability conditions and the formation and properties of the envelop solitons. 相似文献
59.
Shantanu Kumar Biswal Santosh Kumar Agarwalla Munesh Chandra Adhikary 《Astrophysics and Space Science》2012,337(2):645-650
Some recent experimental observations have been shown that inclusion of electron collisions damping in inertial Alfvén wave
(IAW) dynamics may be important for laboratory as well as space plasmas. This paper presents the numerical simulation of model
equation governing the nonlinear dynamics of IAW in low-beta plasmas. When the nonlinearity arises due to the ponderomotive
force and Joule heating driven density perturbations, the model equation turns out to be a modified nonlinear Schr?dinger
equation (MNLS). The electron collisions are introduced only in the electron momentum equation. The damped localized structures
of IAW with sidebands are obtained. Also, the effect of collisional damping on power spectra of magnetic fluctuations with
different scaling laws has been studied. These turbulent structures may be responsible for particle acceleration in laboratory
and space plasmas. 相似文献
60.
Jeewan Chandra Pandey Subhajeet Karmakar Arti Joshi Saurabh Sharma Shashi Bhushan Pandey Anil Kumar Pandey 《天文和天体物理学研究(英文版)》2019,(1)
Using long-term optical, ultraviolet(UV) and X-ray data, we present a study of a classical T Tauri star CV Cha. The V-band light curve obtained from the All Sky Automated Survey(ASAS) shows short as well as long-term variability. The short-term variability could be due to rotational modulation of CV Cha. We derive the rotational period of 3.714 ± 0.001 d for CV Cha. UV light curves obtained from Swift also show the variations. X-ray light curves from XMM-Newton and Swift do not show any significant short as well as long-term variability. However, the light curve from Chandra appears to be variable, which could be due to the emergence of flaring activities. X-ray spectra from all observations are explained well by the single temperature plasma of 0.95 keV with X-ray luminosity of 1030.4erg s-1in the 0.5–7.5 keV energy band. It appears that variability in optical and UV bands could be due to the presence of both hot and cool spots on the surface, while X-ray emission is dominated by magnetic processes. 相似文献