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1.
N. D. Melikian V. S. Tamazian J. A. Docobo A. A. Karapetian G. R. Kostandian R. Iglesias 《Astrophysics》2008,51(3):372-386
Results from a spectral study of one of the brightest cataclysmic variables, the star TT Ari, are presented. They are generally
in good agreement with previous observations, but there are some differences. The luminosity of the star, as well as the equivalent
widths of emission lines, reveal variations that are probably periodic in character. Emission from the star in the CIV 5801Å
and 5812 Å lines is observed for the first time. The observed variations in the symmetry of the broad absorption Balmer series
(beginning with Hβ) may be a consequence of the appearance of a P Cyg line profile. The Hα line manifests a P Cyg profile
consisting of two components corresponding to 600 and 1900 km/s. The average of the ratio EWHα/EWHβ indicates that the formation
of these lines may be explained, at least partially, in terms of a simple photoionization-recombination model.
__________
Translated from Astrofizika, Vol. 51, No. 3, pp. 445–460 (August 2008). 相似文献
2.
This is a study of the stability of strange dwarfs, superdense stars with a small quark core (M
0core
/M
⨀ < 0.017) and an extended crust consisting of atomic nuclei and a degenerate electron gas where the density may be two orders
of magnitude greater than the maximum density for white dwarfs. For a given equation of state, the mass, total number of baryons,
and radius of strange dwarfs are uniquely determined by the central energy density ρ
c
and the energy density ρ
tr
of the crust at the surface of the quark core. Thus, the entire range of variation of ρ
c
and ρ
tr
must be taken into account in studying the stability of these configurations. This can be done by examining a series of configurations
with a fixed rest mass M
0 (total baryon number) of the quark core and different masses of the crust. In each series, ρ
tr
ranges from the value for white dwarfs to ρ
drip
= 4.3∙1011 g/cm3, at which free neutrons are created in the crust. According to the static criterion for stability, stability is lost in an
individual series when the mass of the strange dwarf reaches a maximum as a function of ρ
tr
.
Translated from Astrofizika, Vol. 52, No. 2, pp. 325–332 (May 2009). 相似文献
3.
The observeduvby and Hα indices of member stars of the Hyades and Praesepe clusters have been analysed in detail for rotation effects. The Alpha
Persei, Pleiades and the Centaurus subgroup of the Scorpio—Centaurus association have been reanalysed using the observed indices
instead of the extinction-corrected indices used earlier. The observed rotation effects from the analysis of these cluster
data are found to be in excellent agreement with the theoretical predictions of Collins & Sonneborn (1977). We have also analysed
the α,c and (u − b) values of the member stars of NGC 1976, 2264, 2287, 2422, 4755,1C 2391, IC 2602 and IC 4665 for rotation effects. The results
are found to be consistent with the theoretical predictions.
The observed slopes of the rotation effects were used to determine the zero rotation main sequence values of the intermediate
band photometric indices for selected clusters. We also corrected the observed indices for each star in each cluster using
the theoretical predictions of Collins and Sonneborn and derived the ZRMS values for each cluster. The agreement between the
two determinations is found to be good. The various ZRMS curves were utilised to derive the ZRZAMS values. A preliminary calibration
of the absolute visual magnitudes as a function of α valid for ZRZAMS has also been derived. The ZRMS values of the intermediate
band photometric indices for different clusters and the ZRZAMS values are listed as a function of α.
on leave from Assumption College, Changanacherry, Kerala. 相似文献
4.
A. M. Mickaelian 《Astrophysics》2000,43(3):309-321
A fifth list of objects from the BIG (Byurakan-IRAS galaxies) sample is given: 89 galaxies identified with 59 point sources
from the IRAS Point Source Catalog. The identifications were based on the Digital Sky Survey (DSS), the First Byurakan Survey,
blue and red maps from the Palomar Observatory Sky Survey, and infrared fluxes at 12, 25, 60, and 100 mm in the region of+65°
≤ δ ≤69δ and 5h10m ≤ α ≤9h 15m with an area of 96 deg2. For the identified galaxies the optical coordinates, their departures from the IR coordinates, and the stellar V magnitudes,
morphological types, angular sizes, and position angles were determined. The objects have optical magnitudes in the range
of 14m. 1-21m.5 and angular sizes in the range of 2″-47″. The galaxies are mainly spiral in morphology. Compact galaxies and Seyfert candidates,
interacting pairs, “mergers,” galaxies with companions and superassociations, groups of galaxies (including compact ones),
and others are encountered, which shows the importance of these objects for the study of the relationships among the phenomena
of star formation, activity, and interactions. Finder charts from the DSS are given for these objects. New designations and
numbering are introduced for galaxies in the studied sample.
Translated from Astrofizika, Vol. 43, No. 3, pp. 425-441, July– September, 2000.
The NASA/IPAC Extragalactic Database (NED), operated by the Jet Propulsion Laboratory, California Institute of Technology,
under contract with NASA. 相似文献
5.
A third list of point sources from the IRAS Point Source Catalog (PSC), optically identified with late-type stars, is given.
The list contains data on 34 objects. The identification was based on the Digitized Sky Survey (DSS), the First Byurakan Survey
(FBS). blue and red maps of the Palomar Observatory Sky Survey, and infrared fluxes at wavelengths of 12, 25, 60, and 100
mm in the regions of +61° ≤ δ ≤ +65°, 06h45m ≤ α ≤ 17h28m and +69° ≤ δ ≤ +73°, 03h50m ≤ α ≤ 18h10m. Of 34 objects given in the IRAS PSC as unidentified sources of infrared radiation, 11 are associated with known stars in
existing catalogs, 6 are objects from the FBS survey of late-type stars, and 17 sources remained unknown in the optical range,
3 of them also being sources in the IRAS Serendipitous Survey Catalog (SSC). The optical coordinates, their departures from
the 1R coordinates, the V magnitudes, the color indices CI, and the preliminary spectral subtypes were determined. The objects
have optical magnitudes in the range of 7h.6-13m.6. Finder charts from the DSS are given for 23 objects.
Translated from Astrofizika, Vol. 43, No. 1, pp. 77-84, January–March, 2000. 相似文献
6.
Part three of optically identified point sources from the IRAS Point Source Catalog contains 113 objects. The identifications
were based on the Digitized Sky Survey (DSS), the First Byurakan Survey, blue and red maps from the Palomar Sky Survey, and
infrared fluxes at 12, 25, 60, and 100 μm in the region of +61° ≤ δ ≤ + 65° and 11h15m ≤ α ≤ 18h35m with an area of 200 sq. deg. Of the 119 sources in this region, 6 could not be identified owing to the absence of optical
counterparts with the given coordinates. For the identified objects we determined their optical coordinates, their departures
from the IR coordinates, and their stellar V magnitudes, color indices (CI), and preliminary types. The objects have optical
magnitudes in the range of 8n–21m. Of the 113 objects, 31 turned out to be stars of spectral types K and M, 1 is a planetary nebula, 2 are candidates to be
quasi- stellar objects, and 79 are galaxies. A list of the 48 nonstellar objects is given. The identified galaxies include
Seyfert candidates, interacting pairs, galaxies with companions, superassociations, etc. The galaxies are in groups in many
cases, and the IR emission may be due to heating of intergalactic matter within a group. Finder charts for these objects from
the DSS are given.
Translated from Astrofizika, Vol. 41, No. 2, pp. 251–262, April-June, 1998. 相似文献
7.
Preliminary data are presented on seven “special” objects found in low-dispersion spectral plates of the FBS survey. The first
object, FBS 0250+167, is found to be a class M7 dwarf with a high proper motion (∼5.130 arcsec/year) lying about 3 pc from
the sun. Three of the objects, with spectra of classes M8–M9, are suspected of being long-period Mirids with large mass losses
and surrounded by dense clouds. The three remaining objects have very short low-dispersion spectra on the FBS survey plates
(clearly they are non stellar objects) and are of interest for later detailed study.
__________
Translated from Astrofizika, Vol. 50, No. 1, pp. 73–85 (February 2007). 相似文献
8.
This is an examination of the gravitational instability of the major large-scale perturbation modes for a fixed value of the
azimuthal wave number m = 1 in nonlinearly nonstationary disk models with isotropic and anisotropic velocity diagrams for
the purpose of explaining the displacement of the nucleus away from the geometric center (lopsidedness) in spiral galaxies.
Nonstationary analogs of the dispersion relations for these perturbation modes are obtained. Critical diagrams of the initial
virial ratio are constructed from the rotation parameters for the models in each case. A comparative analysis is made of the
instability growth rates for the major horizontal perturbation modes in terms of two models, and it is found that, on the
average, the instability growth rate for the m = 1 mode with a radial wave number N = 3 almost always has a clear advantage
relative to the other modes. An analysis of these results shows that if the initial total kinetic energy in an isotropic model
is no more than 12.4% of the initial potential energy, then, regardless of the value of the rotation parameter Ω, an instability
of the radial motions always occurs and causes the nucleus to shift away from the geometrical center. This instability is
aperiodic when Ω = 0 and is oscillatory when Ω ≠ 0 . For the anisotropic model, this kind of structure involving the nucleus
develops when the initial total kinetic energy in the model is no more than 30.6% of the initial potential energy. 相似文献
9.
G. A. Krasinsky 《Celestial Mechanics and Dynamical Astronomy》2006,96(3-4):169-217
Improved differential equations of the rotation of the deformable Earth with the two-layer fluid core are developed. The equations describe both the precession-nutational motion and the axial rotation (i.e. variations of the Universal Time UT). Poincaré’s method of modeling the dynamical effects of the fluid core, and Sasao’s approach for calculating the tidal interaction between the core and mantle in terms of the dynamical Love number are generalized for the case of the two-layer fluid core. Some important perturbations ignored in the currently adopted theory of the Earth’s rotation are considered. In particular, these are the perturbing torques induced by redistribution of the density within the Earth due to the tidal deformations of the Earth and its core (including the effects of the dissipative cross interaction of the lunar tides with the Sun and the solar tides with the Moon). Perturbations of this kind could not be accounted for in the adopted Nutation IAU 2000, in which the tidal variations of the moments of inertia of the mantle and core are the only body tide effects taken into consideration. The equations explicitly depend on the three tidal phase lags δ, δ
c, δ
i responsible for dissipation of energy in the Earth as a whole, and in its external and inner cores, respectively. Apart from the tidal effects, the differential equations account for the non-tidal interaction between the mantle and external core near their boundary. The equations are presented in a simple close form suitable for numerical integration. Such integration has been carried out with subsequent fitting the constructed numerical theory to the VLBI-based Celestial Pole positions and variations of UT for the time span 1984–2005. Details of the fitting are given in the second part of this work presented as a separate paper (Krasinsky and Vasilyev 2006) hereafter referred to as Paper 2. The resulting Weighted Root Mean Square (WRMS) errors of the residuals dθ, sin θd for the angles of nutation θ and precession are 0.136 mas and 0.129 mas, respectively. They are significantly less than the corresponding values 0.172 and 0.165 mas for IAU 2000 theory. The WRMS error of the UT residuals is 18 ms. 相似文献
10.
A fourth list of optically identified point sources from the IRAS Point Source Catalog, containing 34 nonstellar objects,
is given. The identifications were made on the basis of the Digitized Sky Survey (DSS), the First Byurakan Survey, blue and
red maps from the Palomar Sky Survey (FBS), and infrared fluxes at 12, 25, 60, and 100 μm in the region of +61° ≤ δ ≤ 65°
and 11h15m ≤ α ≤ 18h35m with an area of 200 sq. deg. For the identified objects we determined their optical coordinates, their departures from the
IR coordinates, their stellar V magnitudes, color indices CI, and preliminary types. The optical magnitudes of the objects
are in the range 12m.5-27m. The identified galaxies include Seyfert candidates, interacting pairs, galaxies with companions, superassociations, etc.
The galaxies are encountered in groups in many cases, and the IR emission may be due to heating of intergalactic matter within
a group. Finder charts from the DDS are given for these objects.
Translated from Astrofizika, Vol. 41, No. 3, pp. 359–366, July–September, 1998. 相似文献
11.
A. V. Getling 《Solar physics》2006,239(1-2):93-111
Two series of solar-granulation images – the La Palma series of 5 June 1993 and the SOHO MDI series of 17 – 18 January 1997
– are analysed both qualitatively and quantitatively. New evidence is presented for the existence of long-lived, quasi-regular
structures (first reported by Getling and Brandt, Astron. Astrophys. 382, L5 (paper I), 2002), which no longer appear unusual in images averaged over 1 – 2-hour time intervals. Such structures appear
as families of light and dark concentric rings or families of light and dark parallel strips (“ridges” and “trenches” in the
brightness distributions). In some cases, rings are combined with radial “spokes” and can thus form “web” patterns. The characteristic
width of a ridge or trench is somewhat larger than the typical size of granules. Running-average movies constructed from the
series of images are used to seek such structures. An algorithm is developed to obtain, for automatically selected centres,
the radial distributions of the azimuthally averaged intensity, which highlight the concentric-ring patterns. We also present
a time-averaged granulation image processed with a software package intended for the detection of geological structures in
aerospace images. A technique of running-average-based correlations between the brightness variations at various points of
the granular field is developed and indications are found for a dynamical link between the emergence and sinking of hot and
cool parcels of the solar plasma. In particular, such a correlation analysis confirms our suggestion that granules – overheated
blobs – may repeatedly emerge on the solar surface. Based on our study, the critical remarks by Rast (Astron. Astrophys. 392, L13, 2002) on the original paper by Getling and Brandt (paper I) can be dismissed. 相似文献
12.
A. P. Mahtessian 《Astrophysics》2011,54(2):162-176
The Schmidt method for constructing the luminosity function of galaxies is generalized to include the dependence of the density
of galaxies on distance in the near universe. The logarithmic luminosity function (LLF) of the field galaxies as a function
of morphological type is constructed. It is found that the LLF for all the galaxies, as well as separately for elliptical
and lenticular galaxies, can be represented as a Schechter function within a narrow range of absolute magnitudes. The LLF
for spiral galaxies is a Schechter function over a rather wide range of absolute magnitudes, −21.0 ≤ M ≤ −14 . The parameter
M* varies little over the spiral galaxies. The parameter α in the Schechter function decreases on going from early to later
spirals. On going from elliptical to lenticular galaxies, from early spiral galaxies and onward to later spiral galaxies,
a decrease in the average luminosity of the galaxies is observed in the bright end, −23 ≤ M ≤ −17.8 . The completeness and
average density of the samples are estimated for galaxies of different morphological types. The average number density of
all the galaxies within the range −23 ≤ M ≤ −13 is 0.126 Mpc-3. 相似文献
13.
A fourth list of point sources from the IRAS Point Source Catalog (PSC) that are optically identified with stars of late spectral
types is given. The list contains data on 41 objects. The identifications were based on the Digital Sky Survey (DSS), the
First Byurakan Survey, blue and red maps of the Palomar Observatory Sky Survey, and infrared fluxes at the wavelengths 12,
25, 60, and 100 μm in the region of +65° ≤ δ ≤ +69° and 05h10m ≤ α ≤ 18h10m. Of the 41 objects, which are given in the IRAS PSC as unidentified sources of infrared emission, 9 are associated with known
stars in existing catalogs while 32 sources remained unidentified in the optical range, one of which is also a source in the
deep IRAS survey (IRAS Serendipitous Source Catalog). The optical coordinates, their departures from the IR coordinates, the
V stellar magnitudes, the color indices CI, and the preliminary spectral subtypes have been determined. The objects have optical
magnitudes in the range of 8m.5-14m.5. Finder charts from the DSS are given for 32 of the objects.
Translated from Astrofizika, Vol. 43, No. 3, pp. 361-368, July–September, 2000. 相似文献
14.
The spectrophotometric temperatures of five Mira-type variable stars are determined using observations in the Pulkovo spectrophotometric
data base in the range from 320–1080 nm. All the resulting temperatures are below the effective temperatures of stars in the
corresponding subclasses. Near the brightness maximum, the temperatures are found to be lower with increasing separation in
time from the maximum.
__________
Translated from Astrofizika, Vol. 50, No. 3, pp. 415–426 (August 2007). 相似文献
15.
We present simple analytic models which predict the peak X-ray emission measure and temperature attained in flares in which
the chromospheric evaporation process takes place either in a single ‘monolithic’ loop or in a loop consisting of several
filaments that are created successively as the energy release process proceeds in time. As possible mechanisms driving chromospheric
evaporation we consider both classical heat conduction from the loop top and non-thermal electron beams. The model predictions
are tested for a set of 18 well studied RHESSI microflares. The results suggest beam driven evaporation in filamented loops
as being capable of accounting for the observed emission measures and temperatures though there are issues with the very high
beam densities needed. On the other hand, estimates of the emission measures achieved by conductive evaporation which are
derived by using the Rosner – Tucker – Vaiana (RTV) scaling law are much larger than the observed ones. Possible reasons for
this discrepancy are discussed. 相似文献
16.
Recent cosmological observations of large-scale structures (red shift of type Ia supernovae) confirm that the universe is
currently expanding at an accelerating rate and its dominant component is dark energy. This has stimulated the development
of the theory of gravity and led to many alternative variants, including tensor-scalar ones. This paper deals with the role
of conformal transformations in the Jordan-Brans-Dicke theory. Variants of intrinsic, conformally coupled, and Einstein representations
are examined. In the Einstein representation an exact analytic solution for the standard cosmological model is obtained. It
is expressed in terms of the relative energy contributions of ordinary matter Ω
m
, the scalar field Ω
CK
, and a term ΩΛ related to the cosmological constant Λ . Information on the evolution of the universe for the case with a minimally coupled
scalar field is given in the form of graphs. 相似文献
17.
Part five of optically identified point sources from the IRAS Point Source Catalog (PSC) contains data on 19 late-type stars.
The identifications were based on the Digitized Sky Survey (DSS), the First Byurakan Survey (FBS), blue and red maps of the
Palomar survey (POSS), and infrared fluxes at 12, 25, 60, and 100 mm in the region of +61° ≤ δ ≤ +65° and 05
h
30
m
≤ α ≤ 18
h
35
m
with an area of 357 sq. deg. Of the 76 objects given in the IRAS PSC as unidentified sources of infrared radiation, 51 are
associated with known stars in existing catalogs, 6 are objects from the FBS of late-type stars, and 19 sources remained unknown
in the optical range. For the identified stars we determined the optical coordinates, their departures from the IR coordinates,
the Vstellar magnitudes, the color indices CI,and the preliminary spectral subtypes. The objects have optical magnitudes in the range of 8
m
−16
m
.Gas-dust shells are assumed to exist around four of the sources. Finder charts from the DSS are given for 19 of the objects.
Translated from Astrofizika, Vol. 42, No. 1, pp. 53–59, January–March, 1999. 相似文献
18.
The second portion of optically identified point sources from the IRAS Point Source Catalog contains 104 objects. The identifications
were made on the basis of the Digitized Sky Survey (DSS), the First Byurakan Survey (FBS), blue and red maps of the Palomar
Survey (POSS), and infrared fluxes at wavelengths of 12, 25, 60, and 100 fim in the region of +61 ° ≤ δ ≤ +65°and 50h30m ≤ α ≤ 11h15m with an area of 157 sq. deg. Of the 114 sources in this region, 10 could not be identified because of the absence of the
corresponding optical counterparts with the given coordinates. For the identified objects we determined their optical coordinates,
their departure from the IR coordinates, the stellar V magnitudes, the color indices CI, and the preliminary types. The objects
have optical magnitudes in the range of 8n–21m. Of the 104 objects, 46 turned out to be stars of spectral types K and M, 1 is a planetary nebula, 3 are QSO candidates,
and 54 are galaxies. In the present work we give a list of the 58 nonstellar objects. The identified galaxies include Seyfert
candidates, interacting pairs, galaxies with companions and superassociations, etc. Finder charts for these objects from the
DSS are given.
Translated from Astrofizika, Vol. 40, No. 4, pp. 581–593, October-December, 1997. 相似文献
19.
A bimetric theory of gravitation with a Lagrangian that is quadratic with respect to “intensities” is considered. All the
post-Newtonian parameters are determined and it is shown that they coincide with the respective parameters of the general
theory of relativity.
Translated from Astrofizika, Vol. 43, No. 2, pp. 303-312, April–June, 2000. 相似文献
20.
Stochastic data in astronomy. II. Search for harmonic components of time series with very large gaps
This is an analysis of certain aspects of using the CLEAN algorithm for Fourier analysis of short segments of time series
and of time series consisting of short segments of length ΔT separated by very long irregular gaps. It is assumed that the
time series contain a harmonic component of amplitude A with a period longer than the length of the longest of the segments
of the time series plus white noise with dispersion N2. Reliability plots are constructed for determining the ranges of the parameters (ν, ϕ) for which the CLEAN procedure can be used to determine the values of ν, the frequency, and ϕ, the phase of the harmonic
component, with a given accuracy. The results of this analysis are used to search for harmonic components in the variation
of the Hβ line profile in spectra of the triple star δ Ori A obtained in 2004 with the BTA telescope at the Special Astrophysical
Observatory of the Russian Academy of Sciences.
__________
Translated from Astrofizika, Vol. 50, No. 2, pp. 281–297 (May 2007). 相似文献