132 research outputs found
Periodic Pattern in the Residual-Velocity Field of OB Associations
An analysis of the residual-velocity field of OB associations within 3 kpc of
the Sun has revealed periodic variations in the radial residual velocities
along the Galactic radius vector with a typical scale length of
lambda=2.0(+/-0.2) kpc and a mean amplitude of fR=7(+/-1) km/s. The fact that
the radial residual velocities of almost all OB-associations in rich
stellar-gas complexes are directed toward the Galactic center suggests that the
solar neighborhood under consideration is within the corotation radius. The
azimuthal-velocity field exhibits a distinct periodic pattern in the region
0<l<180 degrees, where the mean azimuthal-velocity amplitude is ft=6(+/-2)
km/s. There is no periodic pattern of the azimuthal-velocity field in the
region 180<l<360 degrees. The locations of the Cygnus arm, as well as the
Perseus arm, inferred from an analysis of the radial- and azimuthal-velocity
fields coincide. The periodic patterns of the residual-velocity fields of
Cepheids and OB associations share many common features.Comment: 21 page
Level of biogenic and organic substances in a water of the Dniprovs’ke reservoir and Samara River in fall-winter period
Вивчено актуальні проблеми впливу евтрофування Дніпровського водосховища органічними та біогенними речовинами господарсько-побутових і промислових стічних вод на рибогосподарські показники. Проведені досліди показали перевищення ГДК за деякими показниками для рибогосподарських водойм.Вивчено актуальні проблеми впливу евтрофування Дніпровського водосховища органічними та біогенними речовинами господарсько-побутових і промислових стічних вод на рибогосподарські показники. Проведені досліди показали перевищення ГДК за деякими показниками для рибогосподарських водойм.Relevant problems of influence of the Dniprovs’ke reservoir eutrophication by the household sewage on the water quality indices in fishing zones were studied. Investigations disclosed the excess of the maximum permissible concentration of some indices developed for a fishing reservoir
Study of deuteron-proton charge exchange reaction at small transfer momentum
The charge-exchange reaction pd->npp at 1 GeV projectile proton energy is
studied in the multiple-scattering expansion technique. This reaction is
considered in a special kinematics, when the transfer momentum from the beam
proton to fast neutron is close to zero. The differential cross section and a
set of polarization observables are calculated. It was shown that contribution
of the final state interaction between two protons is very significant.Comment: 11 pages, 8 figure
Приближенные методы интегрирования уравнений поплавка гироскопа с ненулевой Гауссовой кривизной
Створюється наукове підґрунтя опису динамічного стану рухомої частини двостепеневого поплавкового гіроскопа в умовах дії на нього зовнішніх збурень довільної структури і фізичної природи. Окреслене коло прикладних задач оптимізації геометрії поплавця.The scientific basis of the analysis of dynamic status of a mobile part of the two-powermode gyro in conditions of operating on it of external disturbances of arbitrary frame and physical nature is under construction. The circle of applied problems of optimization of geometry of a float is delineated.Строится научная основа анализа динамического состояния подвижной части двухстепенного гироскопа в условиях действия на него внешних возмущений произвольной структуры и физической природы. Очерчивается круг прикладных задач оптимизации геометрии поплавка
On the Spiral Structure of the Milky Way Galaxy
We consider the possible pattern of the overall spiral structure of the
Galaxy, using data on the distribution of neutral (atomic), molecular, and
ionized hydrogen, on the base of the hypothesis of the spiral structure being
symmetric, i.e. the assumption that spiral arms are translated into each other
for a rotation around the galactic center by 180{\deg} (a two-arm pattern) or
by 90{\deg} (a four-arm pattern). We demonstrate that, for the inner region,
the observations are best represented with a four-arm scheme of the spiral
pattern, associated with all-Galaxy spiral density waves. The basic position is
that of the Carina arm, reliably determined from distances to HII regions and
from HI and H2 radial velocities. This pattern is continued in the quadrants
III and IV with weak outer HI arms; from their morphology, the Galaxy should be
considered an asymmetric multi-arm spiral. The kneed shape of the outer arms
that consist of straight segments can indicate that these arms are transient
formations that appeared due to a gravitational instability in the gas disk.
The distances between HI superclouds in the two arms that are the brightest in
neutral hydrogen, the Carina arm and the Cygnus (Outer) arm, concentrate to two
values, permitting to assume the presence of a regular magnetic field in these
arms.Comment: 21 pages, 14 fugures; accepted for publication in Astronomichesky
Journal (Astron. Rep.
Kinematics of the outer pseudorings and the spiral structure of the Galaxy
The kinematics of the outer rings and pseudorings is determined by two
processes: the resonance tuning and the gas outflow. The resonance kinematics
is clearly observed in the pure rings, while the kinematics of the gas outflow
is manifested itself in the pseudorings. The direction of systematical motions
in the pure rings depends on the position angle of a point with respect to the
bar major axis and on the class of the outer ring. The direction of the radial
and azimuthal components of the residual velocities of young stars in the
Perseus, Carina, and Sagittarius regions can be explained by the presence of
the outer pseudoring of class R1R2' in the Galaxy. We present models, which
reproduce the directions and values of the residual velocities of
OB-associations in the Perseus and Sagittarius regions, and also model
reproducing the directions of the residual velocities in the Perseus,
Sagittarius, and Carina regions. The kinematics of the Sagittarius region
accurately defines the solar position angle with respect to the bar elongation,
theta_b=45 (+/-5) deg.Comment: 16 pages, 10 figures, accepted for publication in Astronomy Letter
Ошибки интегрирующего гироскопа при детерминированных внешних возмущениях
Наводяться результати аналізу збудженого руху підвісу двохстепеневого гіроскопа за умови спільної дії акустичного навантаження та хитавиці основи. Визначені сталі складові дрейфу інтегруючого гіроскопа за асинхронної і синхронної зміни кутів повороту у часі.The outcomes of the analysis of exited motion подвеса of the two-powermode gyro are resulted at joint action of acoustic loading and swinging of the basis. The constant components of drift of an integrating gyroscope are determined at asynchronous and synchronic change of turn angles in time.Приводятся результаты анализа возбужденного движения подвеса двухстепенного гироскопа при совместном действии акустического нагружения и качки основания. Определены постоянные составляющие дрейфа интегрирующего гироскопа при асинхронном и синхронном изменении углов поворота во времени
Two Large HI Shells in the Outer Galaxy near l=279 degrees
As part of a survey of HI 21-cm emission in the Southern Milky Way, we have
detected two large shells in the interstellar neutral hydrogen near l=279 deg.
The center velocities are +36 and +59 km/s, which puts the shells at kinematic
distances of 7 and 10 kpc. The larger shell is about 610 pc in diameter and
very empty, with density contrast of at least 15 between the middle and the
shell walls. It has expansion velocity of about 20 km/s and swept up mass of
several million solar masses. The energy indicated by the expansion may be as
high as 2.4 X 10^53 ergs. We estimate its age to be 15 to 20 million years. The
smaller shell has diameter of about 400 pc, expansion velocity about 10 km/s
and swept up mass of about 10^6 solar masses.
Morphologically both regions appear to be shells, with high density regions
mostly surrounding the voids, although the first appears to have channels of
low density which connect with the halo above and below the HI layer. They lie
on the edge of the Carina arm, which suggests that they may be expanding
horizontally into the interarm region as well as vertically out of the disk. If
this interpretation is correct, this is the first detection of an HI chimney
which has blown out of both sides of the disk.Comment: 21 pages, 14 jpeg figures, accepted for publication in A
Galactic Rotation Parameters from Data on Open Star Clusters
Currently available data on the field of velocities Vr, Vl, Vb for open star
clusters are used to perform a kinematic analysis of various samples that
differ by heliocentric distance, age, and membership in individual structures
(the Orion, Carina--Sagittarius, and Perseus arms). Based on 375 clusters
located within 5 kpc of the Sun with ages up to 1 Gyr, we have determined the
Galactic rotation parameters
Wo =-26.0+-0.3 km/s/kpc,
W'o = 4.18+-0.17 km/s/kpc^2,
W''o=-0.45+-0.06 km/s/kpc^3, the system contraction parameter K = -2.4+-0.1
km/s/kpc, and the parameters of the kinematic center Ro =7.4+-0.3 kpc and lo =
0+-1 degrees. The Galactocentric distance Ro in the model used has been found
to depend significantly on the sample age. Thus, for example, it is 9.5+-0.7
kpc and 5.6+-0.3 kpc for the samples of young (50 Myr)
clusters, respectively. Our study of the kinematics of young open star clusters
in various spiral arms has shown that the kinematic parameters are similar to
the parameters obtained from the entire sample for the Carina-Sagittarius and
Perseus arms and differ significantly from them for the Orion arm. The
contraction effect is shown to be typical of star clusters with various ages.
It is most pronounced for clusters with a mean age of 100 Myr, with the
contraction velocity being Kr = -4.3+-1.0 km/s.Comment: 14 pages, 4 figures, 2 table
Statistical Survey of Type III Radio Bursts at Long Wavelengths Observed by the Solar TErrestrial RElations Observatory (STEREO)/Waves Instruments: Radio Flux Density Variations with Frequency
We have performed a statistical study of Type III radio bursts observed
by Solar TErrestrial RElations Observatory (STEREO)/Waves between May 2007 and
February 2013. We have investigated the flux density between kHz and
MHz. Both high- and low-frequency cutoffs have been observed in of
events suggesting an important role of propagation. As already reported by
previous authors, we observed that the maximum flux density occurs at MHz on
both spacecraft. We have developed a simplified analytical model of the flux
density as a function of radial distance and compared it to the STEREO/Waves
data.Comment: published in Solar Physic
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