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31.
32.
33.
The radius, mass, total number of baryons, and other parameters of static, spherically symmetric, superdense stars are calculated. A model with one Ricci-flat inner space of arbitrary dimensionality and the approximation p1=?0.5ε + ap for additional components of the energy — momentum tensor are used (ε and ρ are the total energy density and the pressure of the stellar matter and a is a fitting parameter). In the case of white dwarfs, the results of the multidimensional theory do not depend on the dimensionality D of space-time for ?10 ? a ? 10 and coincide with the analogous data of the general theory of relativity (GTR). For neutron stars there is a dependence on D and a. For D>4, in particular, the greatest mass Mmax of a neutron star as a function of a has a maximum at 3<a(D) ? 4, which exceeds the greatest mass M max 0 =2.14 M⊙ in the GTR. A comparison of theoretical results with observational data determines the allowable values of a. Data for PSR 1913 + 16 lead to 0.2 ≤ a ≤ 9.2 in the case of D=26, while the results of [P. C. Joss and S. A. Rappaport, Annu. Rev. Astron. Astrophys.,22, 537 (1984)] lead to the stricter limits 1 ≤ a ≤ 7.4. 相似文献
34.
35.
R. U. Claudi M. Cancian M. Barbieri R. Gratton S. Desidera M. Montalto G. P. Piotto S. Scuderi 《Astrophysics and Space Science》2006,304(1-4):251-251
RATS is an Italian project devoted to Hot Jupiter search with the transit method. A planet transiting in front of a host star can be mimed by several, and well defined, astrophysical phenomena (Brown, 2003). In order to recognize these false alarms we can utilize a preventive strategy to limit false alarm rates and a spectroscopic follow up to refuse no transit candidates. As preventive strategy it is important to develop an accurate target field selection, with well defined requisites, in order to maximize the solar type star numbers and to minimize the risk of possible astrophysical false alarms. 相似文献
36.
Helios-1 and 2 spacecraft allowed a detailed investigation of the radial dependence of the interplanetary magnetic field components between 0.3 and 1 AU. The behaviour of the radial component B
ris in a very good agreement with Parker's model (B
r r
-2) and the azimuthal component B
also shows a radial dependence which is close to theoretical predictions (B
r
-1). Experimental results for the normal component B
and for the field magnitude B are consistent with those from previous investigations. The relative amplitude of the directional fluctuations with periods less than 12 hr is essentially independent of heliocentric distance, while their power decreases approximately as r
–3 without any appreciable difference between higher and lower velocity regimes.Also at Laboratorio Plasma nello Spazio, CNR, Frascati. 相似文献
37.
D. P. sharma A. K. Jain S. C. Chakravarty K. Kasturirangan K. R. Ramanathan U. R. Rao 《Astrophysics and Space Science》1972,17(2):409-425
The electron production rates in the night-time D-region arising from the transit of strong celestial X-ray sources Sco X-1,
Tau X-1 and Galactic Center are estimated and compared with the ambient electron production rates resulting from other known
stable agencies. Using the experimentally measured values of the night-time electron densities, the number of additional electrons/cc
expected from the passage of these sources is computed. For the 164 kHz transmission from Tashkent, received at Ahmedabad,
the associated enhancement in the attenuation is calculated using the full wave admittance technique of Barron and Budden.
Reasonable agreement is shown to exist between the calculated values of the attenuation and those of direct observations. 相似文献
38.
Effects of Hall current on free convection and mass transfer flow through a porous medium bounded by a vertical surface has been analysed. The problem is solved analytically. The velocity profiles are shown on graphs. Effects ofm (Hall parameter).K
* (permeability parameter), and Sc (Schmidt number) on velocity are discussed. 相似文献
39.
U. S. Chaubey 《Astrophysics and Space Science》1984,103(2):385-389
The evolutionary processes of close binary stars have been examined. It is found that there is a strong deficit of binaries evolving in CaseA in the whole mass range. Probably the binary stars having binary separation corresponding to CaseA evolution cannot form. 相似文献
40.
M. Erdik K. ŞeşetyanM.B. Demircioğlu U. HancılarC. Zülfikar 《Soil Dynamics and Earthquake Engineering》2011
This article summarizes the work done over the last decades regarding the development of new approaches and setting up of new applications for earthquake rapid response systems that function to estimate earthquake losses in quasi-real time after an earthquake. After a critical discussion of relevant earthquake loss estimation methodologies, the essential features and characteristics of the available loss estimation software are summarized. Currently operating near-real-time loss estimation tools can be classified under two main categories depending on the size of area they cover: global and local systems. For the global or regional near-real-time loss estimation systems: GDACS, WAPMERR, PAGER, and NERIES-ELER methodologies are presented together with their loss estimations for the 2009 Abruzzo (L’Aquila) earthquake in Italy. Examples are provided for the local rapid earthquake loss estimation systems, including the Taiwan Earthquake Rapid Reporting System, Real-time Earthquake Assessment Disaster System in Yokohama, Real Time Earthquake Disaster Mitigation System of the Tokyo Gas Co., and Istanbul Earthquake Rapid Response System. 相似文献