Showing papers in "Serbian Astronomical Journal in 1999"
TL;DR: Using a semiclassical approach, the authors calculated electron−, proton−, He −, Mg II−, Si II-and Fe II-impact line widths and shifts for 189 Ca I−multiplets as a function of temperature.
Abstract: Using a semiclassical approach, we have calculated electron−, proton−, He
II−, Mg II-, Si II- and Fe II-impact line widths and shifts for 189 Ca I
multiplets as a function of temperature. Perturbers selected here, are the
main perturbers in solar and stellar atmospheres.
8 citations
TL;DR: Using a semiclassical approach, the authors calculated the impact line widths and shifts for 32 Zn I multiplets as a function of the temperature and perturber density, and showed that electron, proton, and He II impact lines overlap.
Abstract: Using a semiclassical approach, we have calculated electron−, proton− and He
II−impact line widths and shifts for 32 Zn I multiplets as a function of
temperature and perturber density.
5 citations
TL;DR: Using a semiclassical approach, this article calculated electron−, proton−, and He III−impact line widths and shifts for 9 Ar VIII transitions as a function of temperature and perturber density.
Abstract: Using a semiclassical approach, we have calculated electron−, proton−, and He
III−impact line widths and shifts for 9 Ar VIII transitions as a function of
temperature and perturber density.
4 citations
TL;DR: In this article, for the first time, the elliptical and Thiel- Innes elements for the following interferometric pairs are presented: WDS 00416+2438 =======¯¯ WRH, WDS 03271+1845 = CHARA 10, and WDS 04044+2406 = McA 13 Aa.
Abstract: In this paper, for the first time, are presented elliptical and Thiel- Innes
orbitatal elements for the following interferometric pairs: WDS 00416+2438 =
WRH, WDS 03271+1845 = CHARA 10, WDS 04044+2406 = McA 13 Aa, WDS 17095+4047 =
McA 45 and WDS 23019+4219 = o And Aa. For the pairs WDS 03271+1845 = CHARA 10
andWDS 04044+2406 = McA 13 Aa are calculated total masses and dynamical
parallaxes which are compared with corresponding Hipparcos parallaxes.
4 citations
TL;DR: In this paper, a semiclassical approach was used to calculate the impact line widths and shifts for 52 Be III multiplets as a function of temperature and perturber density.
Abstract: Using a semiclassical approach, we have calculated electron-, proton-, and He II-impact line widths and shifts for 52 Be III multiplets as a function of temperature and perturber density. The electron temperatures are 10,000 K 20,000 K; 50,000 K; 100,000 K 200,000K and 300,000 K and perturber densities are from 10(exp)11 cm(exp)-3 up to 10(exp)21 cm(exp)-3.
2 citations
TL;DR: Using the semiclassical perturbation formalism, the authors calculated electron-, proton-, and ionized helium-impact line widths and shifts for six Au I lines as a function of temperature and perturber density.
Abstract: Using the semiclassical perturbation formalism, we have calculated electron-,
proton-, and ionized helium-impact line widths and shifts for six Au I lines
as a function of temperature and perturber density. Electron-impact
broadening parameters for eight Au II transitions have been calculated within
the modified semiempirical approach.
2 citations
TL;DR: In this paper, the variations of universal times difference UT1-TAI and Earth's rotation parameters were studied in the frequency range of 3====== - 8 yr−1 as a function of the solar activity.
Abstract: The variations of universal times difference UT1-TAI and Earth’s rotation
instantaneous pole coordinates (X,Y) are studied in the frequency range of 3
- 8 yr−1 as a function of the solar activity. It is found that power spectrum
concentrations C1 and C2 are common to solar activity indicators and Earth’s
rotation parameters (ERP). The linear correlation between them is also not a
fortuitous one. Accordingly, by the results of this study the hypothesis of
Djurovic and Pâquet (1996; 1999) that the primary cause of 4-6 year
oscillation lies in solar irradiance is confirmed. Between several mechanisms
responsible for the ERP variations as the most probable are considered the
variations of solar irradiance spectral structure (especially large in its UV
range) and variations of intensity of cosmic X-rays reaching the Earth’s
surface.
2 citations
TL;DR: In this article, the authors used the data from the Gliese-Jahreiss Catalogue and a particular form of the galactic potential to construct galactocentric orbits for nearby stars.
Abstract: Using the data from the Gliese-Jahreiss Catalogue and a particular form of
the galactic potential the authors construct galactocentric orbits for nearby
stars. The potential used in our paper is stationary and axially symmetric
with three contributors - bulge, disc and dark corona. In the calculating of
the galactocentric phase coordinates the distance of the Sun to the galactic
plane is neglected, the asymmetric drift is not, whereas the components of
the solar motion are varied; the distance of the Sun to the axis of galactic
rotation and the corresponding value of the circular velocity are assumed
according to the model used in the paper. The obtained orbits (projection on
meridional plane) in a vast majority are box-like, or more precisely
trapezium-like. The effect of the assumed solar motion is discussed and
comparisons with results obtained by applying different potentials and
initial conditions are made.
1 citations
TL;DR: In this article, the authors used the semiclassical perturbation approach, and calculated the broadening parameters for different perturbations of interest for Li, C III, N IV, N V, and O V 3s3S-3p3Po.
Abstract: By using the semiclassical perturbation approach, Stark broadening parameters
due to the interaction with a selection of perturbers of interest for
recently published experimental results for Li - like B III, C IV, N V and O
VI 3s2S-3p2Po, and for Be - like B II, C III, N IV and O V 3s3S-3p3Po
multiplets, have been calculated. The results are presented as a function of
temperature for a perturber density of 1017cm−3. The influence of resonance
contribution for B II, differences in Stark broadening parameters if we take
oscillator strengths calculated within the Coulomb approximation or taken
from TOP Database, and the influence of transitions with different parent
terms, have been discussed as well.
1 citations
TL;DR: In this article, the rotation of a test spiral galaxy with two contributors -the disc and the corona -was considered, and it was found that the homogeneous sphere is almost unavoidable if the circular velocity has a continuous increase.
Abstract: The rotation of a test spiral galaxy with two contributors - the disc and the
corona - is considered. The disc is exponential, whereas the corona is the
dark subsystem. For the latter several variants of mass distribution are
considered. It is found that the homogeneous sphere is almost unavoidable if
the circular velocity has a continuous increase, at least in its observable
part. On the other hand the rather often applied quasi-isothermal law offers
the most satisfactory fit for the case of constant circular velocity though
the classical Schuster law may also be used, especially taking into account
its simplicity and the consequent possibility of generalising its potential
towards the more general case of axial symmetry.
1 citations
TL;DR: In this paper, the gravitational field effect on atomic data for H and C IV transitions is considered as a perturbation of initial and final energy levels. But the effect increases with the principal quantum number.
Abstract: The gravitational field effect on atomic data for H and C IV transitions are
considered as a perturbation of initial and final energy levels. We found
that this perturbation increases with the principal quantum number. Here we
give several expressions for estimation of this effect and its influence on
atomic data parameters. Also, the calculations of atomic data for 1s − 2p
(Lyα) and 2s − 3p transitions of hydrogen atom as well as atomic data for
2s2S1/2−2p2P0 1/2,3/2 transitions of C IV (1UV) as a function of deformation
of energy levels due to gravitation field and gravitational redshift are
given. The gravitational field effect should be estimated and should be taken
into account in calculation of atomic data for emitters in Broad Line Regions
(BLRs) of Active Galactic Nuclei (AGN).
TL;DR: In this article, the authors investigate the influence of recent advances in research on the gaseous content of the universe on our knowledge of star formation histories of spiral galaxies, and find that large quantities of gas which has not been astrated or been observed only weakly are bound to galaxies at later epochs, and present a potential reservoir of gas not only for solution of the gas consumption puzzle in spiral disks, but also a fuel for future star formation.
Abstract: We investigate the influence of recent advances in research on the gaseous
content of the universe on our knowledge of star formation histories of
spiral galaxies. The discovery of low-redshift population of absorbers and
first steps made in understanding of the transition between high-redshift
intergalactic and low-redshift galactic population of QSO absorption systems
significantly reshape our picture of the gaseous content of the universe. It
turns out that large quantities of gas which has not been astrated or
astrated only weakly are bound to galaxies at later epochs, and present a
potential reservoir of gas not only for solution of the gas consumption
puzzle in spiral disks, but also a fuel for future star formation. This
baryonic transition, although still hard to establish quantitatively, is a
result of the simple physical processes. The resulting increase in the star
formation timescales of spiral galaxies has some interesting consequences for
the long-term future development of life and intelligent observers in the
galactic context. Admittedly highly speculative, this qualitative picture may
hopefully provide a motivation for detailed numerical modelling of the
physical processes involved.
TL;DR: While certain basic tendencies and facts in the Europian tradition relating to dreams about the cosmos and the elucidation of its secrets, the devices for flying into those expanses, even about moving onto other planets in order to solve some earthly problems, are more or less known, Russia's achievements which preceded the spectacular cosmic flights, making them possible in some way, due to a concurrence of various circumstances, are very little known or are wholly unknown outside of a narrow circle of experts as discussed by the authors.
Abstract: While certain basic tendencies and facts in the Europian tradition relating to dreams about the cosmos and the elucidation of its secrets, the devices for flying into those expanses, even about moving onto other planets in order to solve some earthly problems, are more or less known, Russia’s achievements which preceded the spectacular cosmic flights, making them possible in some way, due to a concurrence of various circumstances, are very little known or are wholly unknown even in Russia herself outside of a narrow circle of experts. It is only since not long ago that are being published some results of researches from all manner of documents which have been more or less under embargo for decades. These documents are very important for the analysis of many philosophic and scientific situations of our time. 2. RUSSIAN COSMISM AND ITS UPRI-
TL;DR: In this paper, the physical constraints were applied in the problem of deconvolution by explicitly correcting noise affected Fourier components of the unknown parameters distribution, and the method gave the constrained estimate optimal in the quadratic sense, i.e. the estimate closest to the exact solution in the Euclidean space of solutions.
Abstract: The physical constraints were applied in the problem of deconvolution by
explicitly correcting noise affected Fourier components of the unknown
distribution. The method gives the constrained estimate optimal in the
quadratic sense, i.e. the estimate closest to the exact solution in the
Euclidean space of solutions. The properties of the method were theoretically
examined and some practical applications in the astronomical spectroscopy
have been effected. The method is compared with the similar Fourier spectrum
extrapolation procedures; as a consequence application of the method is
recommended particularly in the case of low signal-to-noise measurements.
TL;DR: In this article, it was shown that a trough, L = 4.6, located outside the plasmapause, is capable of guiding whistler-mode waves in frequency in the range 0.5fBmin−0.64fbmin, from one hemisphere to the other.
Abstract: Ray-tracing calculations show that a trough, L = 4.6, located in the region
outside the plasmapause is capable to guide whistler-mode waves in frequency
range 0.5fBmin−0.64fBmin, from one hemisphere to the other. From an initial
position rays propagate in unducted mode up to h ∼ 14000 km where they are
trapped inside the trough. Propagation along the trough is possible only with
great shifting of wave normal direction in respect to the direction of the
geomagnetic induction B, following the variations of the magnitude of the
ambiental geomagnetic induction, or those of ratio f/fB. On leaving the
trough rays propagate in unducted mode downward in the magnetosphere.
TL;DR: In this paper, the existence of the Stark width dependence on the upper-level ionization and the potential of the quantum transition have been presented for the four types of 4s' - 4p' transitions (4s', 4p', 4d' and 3d' 4p').
Abstract: The existence of the Stark width dependence on the upper-level ionization
potential of the quantum transition have been presented for the four types of
transitions (4s’ - 4p’, 4p’ - 4d’, 4p - 5s, 3d - 4p’) in the singly ionized
argon spectrum (Ar II). On the basis of established regularities the Stark
width values for 6 spectral lines, not measured or calculated before, have
been predicted. Critical analysis of the existing experimental Stark width
data are, also, given.