Observations of hydrogen deficient binary Upsilon sagittarii     

N. Kameswara Rao  V. R. Venugopal 《Journal of Astrophysics and Astronomy》1985,6(2):101-112

The absolute magnitudeM _v of the hydrogen deficient binary υ Sgr has been estimated as -4.8 ± 1.0 from the distribution of the interstellar reddening, polarization and interstellar lines of the surrounding stars. From the ANS observations obtained at the time of the secondary eclipse, it appears that the hotter secondary is surrounded by a disc with colours of a B8-B9 star. The λ 1550 CIv absorption line arising in the stellar wind does not show any change in strength during the secondary minimum. The upper limit to the mass-loss rate from the high temperature wind is estimated as ≤ 5 × 10^-7 M⊙ yr^-1 from the 2 cm and 6 cm radio observations. Based on observations obtained with the Astronomical Netherlands Satellite and VLA. The National Radio Astronomy Observatory’s Very Large Array at Socorro, New Mexico is operated by Associated Universities Inc. under contract with the National Science Foundation.  相似文献   

The onset of shock wave in an electrically conducting and radiating gas     

A. Kumar  L. P. Singh  R. Shyam 《Astrophysics and Space Science》1985,111(1):131-137

The present work applies the method of characteristics to study the behaviour of planar and cylindrical wave-heads propagating through a perfectly electrically conducting and thermally radiating inviscid gas under the optically thin limit in the presence of a transverse magnetic field. The true nonlinear progress of the flow variable gradients at the wavefront is predicted and the critical distance at which the characteristics pile up at the wavefront to form a shock wave is obtained. It is investigated as to how the effects of radiative flux, the magnetic field strength and the specific heat ratio influence the process of steepening or flattening of the characteristic wavefront.  相似文献   

Polarization observations of giant radio pulses from the millisecond pulsar B1937+21 at a frequency of 600 MHz     

M. V. Popov  V. A. Soglasnov  V. I. Kondrat’ev  S. V. Kostyuk 《Astronomy Letters》2004,30(2):95-99

We performed polarization observations of giant radio pulses from the millisecond pulsar B1937+21. The observations were carried out in July 2002 with the 64-m Kalyazin radio telescope at a frequency of 600 MHz in two polarization channels with left-and right-hand circular polarizations (RCP and LCP). We used the S2 data acquisition system with a time resolution of 125 ns. The duration of an observing session was 20 min. We detected twelve giant radio pulses with peak flux densities higher than 1000 Jy; five and seven of these pulses appeared in the RCP and LCP channels, respectively. We found no event that exceeded the established detection threshold simultaneously in the two polarization channels. Thus, we may conclude that the detected giant pulses have a high degree of circular polarization, with the frequency of occurrence of RCP and LCP pulses being the same.  相似文献   

Massless scalar field in Robertson-Walker space-time     

S. D. Maharaj  R. Maartens  A. Beesham 《Astrophysics and Space Science》1990,167(2):329-333

Recently, exact spatially-homogeneous solutions have been found for a conformally invariant massless scalar fieldS(t) coupled to a Robertson-Walker geometry. We investigate extending these solutions to inhomogeneous scalar fieldsS(t, x ^l ). For an isotropic scalar fieldS(t, r) we find a solution satisfying three of the five field equations. If we use REDUCE, we show that the remaining equations forceS=S(t).  相似文献   

Line forming regions in active galaxies and their nuclei     

J. E. Dyson  R. J. R. Williams  J. J. Perry 《Astrophysics and Space Science》1996,237(1-2):187-206

The spectra of active galaxies and their nuclei are rich in emission and absorption line features. A major aim of present research is the development of self-consistent hydrodynamic models for the production of the line-forming regions. We here review such modelling and stress the central role played by shock phenomena induced by winds and explosions on scales ranging from the circumstellar to the intergalactic.  相似文献   

Multicomponent magnetizations in the Foyers Old Red Sandstone (northern Scotland) and their bearing on lateral displacements along the Great Glen Fault   总被引：1，自引：0，他引：1  

K. M. Storetvedt  E. Tveit  E. R. Deutsch  G. S. Murthy 《Geophysical Journal International》1990,102(1):151-163

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The accessibility of a network: The great lakes corridor passenger as an example     

Dr. Abdullah R. Al.-Kandari 《GeoJournal》1986,12(3):255-266

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Modeling X-Ray Photoionized Plasmas Produced at the Sandia Z-Facility     

P. A. M. Van Hoof  M. E. Foord  R. F. Heeter  J. E. Bailey  H.-K. Chung  M. E. Cuneo  W. H. Goldstein  V. Jonauskas  F. P. Keenan  R. Kisielius  D. A. Liedahl  C. Ramsbottom  S. J. Rose  P. T. Springer  R. S. Thoe 《Astrophysics and Space Science》2005,298(1-2):147-153

In experiments at the high-power Z-facility at Sandia National Laboratory in Albuquerque, New Mexico, we have been able to produce a low density photoionized laboratory plasma of Fe mixed with NaF. The conditions in the experiment allow a meaningful comparison with X-ray emission from astrophysical sources. The charge state distributions of Fe, Na and F are determined in this plasma using high resolution X-ray spectroscopy. Independent measurements of the density and radiation flux indicate unprecedented values for the ionization parameter ξ = 20–25 erg cm s⁻¹ under nearly steady-state conditions. First comparisons of the measured charge state distributions with X-ray photoionization models show reasonable agreement, although many questions remain.  相似文献   

Asymptotic giant branch superwind speed at low metallicity     

Jonathan R. Marshall  Jacco Th. van Loon  Mikako Matsuura  Peter R. Wood  Albert A. Zijlstra  Patricia A. Whitelock 《Monthly notices of the Royal Astronomical Society》2004,355(4):1348-1360

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Simulated estimation of hydrological loads from GRACE     

K.-W. Seo  C. R. Wilson 《Journal of Geodesy》2004,78(7-8):442-456

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