408 research outputs found
Techniques for assessing the investment attractiveness of a commercial organization based on classical methods of strategic economic analysis
Purpose: The development of methodological support for assessing the investment attractiveness of a commercial organization, considering modern information requests of stakeholders. Design/Methodology/Approach: As part of the research, the authors have developed an algorithm for investment attractiveness assessment of a commercial organization by using the scenario method of economic analysis. Findings: It is proved that the main disadvantages of the existing methods of assessing investment attractiveness are: the lack of strategic orientation of the assessment; ignoring the influence of most external and internal factors of activity; the inability to assess the risk of investing in the analyzed object; the need to compare with the level of investment attractiveness of similar organizations for an objective interpretation of the results. Practical implications: To eliminate the significant shortcomings of modern methodological support in this area, the authors recommend the use of scenario method of strategic economic analysis in the process of assessing the investment attractiveness of the organization. Originality/Value: The scenario method of strategic economic analysis proposed by the authors complements the existing approaches with the ability to take into account potential risks when making a far-sighted decision to invest in an organization by combining the results of retrospective analysis and forecasting changes in the quantitative and qualitative characteristics of financial and economic activity.peer-reviewe
Ongoing Mass Transfer in the Interacting Galaxy Pair NGC 1409/10
I present two-band HST STIS imaging, and WIYN spectral mapping, of ongoing
mass transfer in the interacting galaxy pair NGC 1409/10 (where NGC 1410 is the
Seyfert galaxy also catalogued as III Zw 55). Archival snapshot WFPC2 imaging
from the survey by Malkan et al. showed a dust feature stretching between the
galaxies, apparently being captured by NGC 1409. The new images allow estimates
of the mass being transferred and rate of transfer. An absorption lane
typically 0.25" (100 pc) wide with a representative optical depth tau_B = 0.2
cuts across the spiral structure of NGC 1410, crosses the 7-kpc projected space
between the nuclei, wraps in front of and, at the limits of detection, behind
NGC 1409, and becomes a denser (tau_B = 0.4) polar feature around the core of
NGC 1409. Combination of extinction data in two passbands allows a crude
three-dimensional recovery of the dust structure, supporting the front/back
geometry derived from colors and extinction estimates. The whole feature
contains of order solar masses in dust, implying about 2x10^7 solar
masses of gas, requiring a mass transfer rate averaging ~1 solar mass per year
unless we are particularly unlucky in viewing angle. Curiously, this
demonstrable case of mass transfer seems to be independent of the occurrence of
a Seyfert nucleus, since the Seyfert galaxy in this pair is the donor of the
material. Likewise, the recipient shows no signs of recent star formation from
incoming gas, although NGC 1410 has numerous luminous young star clusters and
widespread H-alpha emission.Comment: 27 pages, 9 figures. Accepted for the Astronomical Journal, March
200
Estimating the Dark Halo Mass from the Relative Thickness of Stellar Disks
We analyze the relationship between the mass of a spherical component and the
minimum possible thickness of stable stellar disks. This relationship for real
galaxies allows the lower limit on the dark halo mass to be estimated (the
thinner the stable stellar disk is, the more massive the dark halo must be). In
our analysis, we use both theoretical relations and numerical N-body
simulations of the dynamical evolution of thin disks in the presence of
spherical components with different density profiles and different masses. We
conclude that the theoretical relationship between the thickness of disk
galaxies and the mass of their spherical components is a lower envelope for the
model data points. We recommend using this theoretical relationship to estimate
the lower limit for the dark halo mass in galaxies. The estimate obtained turns
out to be weak. Even for the thinnest galaxies, the dark halo mass within four
exponential disk scale lengths must be more than one stellar disk mass.Comment: 20 pages including 6 figures. To be published in Astronomy Letters
(v. 32, No. 10, pp. 649-660, 2006
Hydrodynamic Processes in Young Binary Systems as a Source of Cyclic Variations of Circumstellar Extinction
Hydrodynamic models of a young binary system accreting matter from the
remnants of a protostellar cloud have been calculated by the SPH method. It is
shown that periodic variations in column density in projection onto the primary
component take place at low inclinations of the binary plane to the line of
sight. They can result in periodic extinction variations. Three periodic
components can exist in general case. The first component has a period equal to
the orbital one and is attributable to the streams of matter penetrating into
the inner regions of the binary. The second component has a period that is a
factor of 5-8 longer than the orbital one and is related to the density waves
generated in a circumbinary (CB) disk. The third, longest period is
attributable to the precession of the inner asymmetric region of CB disk. The
relationship between the amplitudes of these cycles depends on the model
parameters as well as on the inclination and orientation of the binary in
space. We show that at a dust-to-gas ratio of 1:100 and and a mass extinction
coefficient of 250 cm g, the amplitude of the brightness variations
of the primary component in the V-band can reach at a mass accretion rate
onto the binary components of yr and a
inclination of the binary plane to the line of sight. We discuss possible
applications of the model to pre-main-sequence stars.Comment: 13 pages, 6 figures, published in Astronomy Letters (v.33, 2007
Bimodal Brightness Oscillations in Models of Young Binary Systems
We consider a model for the cyclic activity of young binary stars that
accrete matter from the remnants of a protostellar cloud. If the orbit of such
a binary system is inclined at a small angle to the line of sight, then the
streams of matter and the density waves excited in the circumbinary disk can
screen the primary component of the binary from the observer. To study these
phenomena by the SPH (smoothed particle hydrodynamics) method, we have computed
grids of hydrodynamic models for binary systems based on which we have
constructed the light curves as a function of the orbital phase.The main
emphasis is on investigating the properties of the brightness oscillations.
Therefore, the model parameters were varied within the following ranges: the
component mass ratio q = M2 : M1 = 0.2 - 0.5 and the eccentricity e = 0 - 0.7.
The parameter that defined the binary viscosity was also varied. We adopted
optical grain characteristics typical of circumstellar dust. Our computations
have shown that bimodal oscillations are excited in binaries with eccentric
orbits, provided that the binary components do not differ too much in mass. In
this case, the ratios of the periods and amplitudes of the bimodal oscillations
and their shape depend strongly on the inclination of the binary plane and its
orientation relative to the observer. Our analysis shows that the computed
light curves can be used in interpreting the cyclic activity of UX Ori stars.Comment: 14 pages, 5 figures, 1 tabl
Brightness Oscillations in Models of Young Binary Systems with Low-Mass Secondary Components
We consider a model for the cyclic brightness variations of a young star with
a low-mass companion that accretes matter from the remnants of a protostellar
cloud. At small inclinations of the binary orbit to the line of sight, the
streams of matter and the density waves excited in the circumbinary disk can
screen the primary component of the binary from the observer. To study these
phenomena, we have computed grids of hydrodynamic models for binary systems by
the SPH method based on which we have constructed the phase light curves as a
function of the rotation angle of the apsidal line relative to the observer.
The model parameters were varied within the following ranges: the component
mass ratio q = 0.01-0.1 and the eccentricity e = 0-0.5. We adopted optical
grain characteristics typical of circumstellar dust. Our computations have
shown that the brightness oscillations with orbital phase can have a complex
structure. The amplitudes and shapes of the light curves depend strongly on the
inclination of the binary orbit and its orientation relative to the observer
and on the accretion rate. The results of our computations are used to analyze
the cyclic activity of UX Ori stars.Comment: 13 pages,8 figures, 1 tabl
37 GHz observations of narrow-line Seyfert 1 galaxies
Observations at 37 GHz, performed at Mets\"ahovi Radio Observatory, are
presented for a sample of 78 radio-loud and radio-quiet narrow-line Seyfert 1
(NLS1) galaxies, together with additional lower and higher frequency radio data
from RATAN-600, Owens Valley Radio Observatory, and the Planck satellite. Most
of the data have been gathered between February 2012 and April 2015 but for
some sources even longer lightcurves exist. The detection rate at 37 GHz is
around 19%, comparable to other populations of active galactic nuclei presumed
to be faint at radio frequencies, such as BL Lac objects. Variability and
spectral indices are determined for sources with enough detections. Based on
the radio data, many NLS1 galaxies show a blazar-like radio spectra exhibiting
significant variability. The spectra at a given time are often inverted or
convex. The source of the high-frequency radio emission in NLS1 galaxies,
detected at 37 GHz, is most probably a relativistic jet rather than star
formation. Jets in NLS1 galaxies are therefore expected to be a much more
common phenomenon than earlier assumed.Comment: Accepted for publication in A&A. Table of 37 GHz data will be
available at the CDS soo
Effect of control of a fast-electron beam using a ceramic channel
At present, experiments with the use of ions with an energy on the order of MeV are intended for the application of radiation with a spot size of about one micrometer for material analysis, surface modification, and cell surgery. In this work, the possibility of controlling a beam of accelerated electrons by using a ceramic channel in the case of its inclination both in the vertical and in horizontal planes is demonstrate
Mixed Morphology Pairs as a Breeding Ground for Active Nuclei
Mixed morphology pairs offer a simplification of the interaction equation
that involves a gas-rich fast rotator paired with a gas-poor slow rotator. In
past low resolution IRAS studies it was assumed that the bulk of the far
infrared emission originated in the spiral component. However our ISO studies
revealed a surprising number of early-type components with significant IR
emission some of which turned out to show active nuclei. This motivated us to
look at the current statistics of active nuclei in mixed pairs using the
FIR-radio continuum correlation as a diagnostic. We find a clear excess of
early-type components with radio continuum emission and an active nucleus. We
suggest that they arise more often in mixed pairs via cross fueling of gas from
the spiral companion. This fuel is more efficiently channeled into the nucleus
of the slow rotating receptor. In a sample of 112 mixed-morphology pairs from
the Karachentsev catalog we find that about 25-30% of detected mixed pairs show
a displacement from the radio-FIR relation defined by normal star forming
galaxies. The latter objects show excess radio continuum emission while others
extend the relation to unusually high radio and FIR flux levels. Many of the
outliers/extreme emitters involve an early-type component with an active
nucleus. The paired E/S0 galaxies in the sample exhibit a significant excess
detection fraction and a marginal excess luminosity distribution compared to
isolated unpaired E/S0 galaxies.Comment: 3 figure
The Polar Stellar Ring and Dark Halo of NGC 5907
Numerical simulations of the disruption of a dwarf companion moving in the
polar plane of a massive galaxy are presented. The constructed model is
compared with observational data on the recently discovered
low-surface-brightness stellar ring around galaxy NGC 5907. Constraints on the
ring lifetime (<=1.5 gyr after the first approach of the galaxies), on the
structure of companion -- the ring presecursor, and on mass of dark halo of the
main galaxy in whose gravitational field the companion moves are provided. The
dark halo mass within 50 kpc of NGC 5907 center cannot exceed 3 or 4 "visible"
masses.Comment: 8 pages, 6 figures, article published in Astronomy Letters, Vol.26,
No.5, 2000, pp277-28
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