254 research outputs found
Long term variability of the Broad Emission Line profiles in AGN
Results of a long-term monitoring ( years) of the broad line and
continuum fluxes of three Active Galactic Nuclei (AGN), 3C 390.3, NGC 4151, and
NGC 5548, are presented. We analyze the H and H profile
variations during the monitoring period and study different details (as bumps,
absorption bands) which can indicate structural changes in the Broad Line
Region (BLR). The BLR dimensions are estimated using the time lags between the
continuum and the broad lines flux variations. We find that in the case of 3C
390.3 and NGC 5548 a disk geometry can explain both the broad line profiles and
their flux variations, while the BLR of NGC 4151 seems more complex and is
probably composed of two or three kinematically different regions.Comment: 10 pages, 9 figures, New Astronomy Reviews (Proceeding of 7th
SCSLSA), in pres
The SCR flare of 16 February 1984 as recorded by the Sayan spectrograph
The Sayan cosmic ray (CR) spectrograph recorded an SCR flare that occurred on 16 February 1984. Data from both 1-hour and 110-minute duration measurements in 10 channels with different energy sensitivity (of neutron monitors HM-64 located at different depths in the atmosphere, and of a neutron, multiple neutron and rigid mumeson component lead-less detector) is presented. The parameters of the SCR variation spectrum are evaluated and it is shown that the recording of multiple neutrons at the same geographic point and at the same level in the atmosphere provides information similar to that from a spectrographic complex of instruments
On the methanol emission detection in the TW Hya disc: the role of grain surface chemistry and non-LTE excitation
The recent detection of gas-phase methanol (CHOH) lines in the disc of TW
Hya by Walsh et al. provided the first observational constraints on the complex
O-bearing organic content in protoplanetary discs. The emission has a ring-like
morphology, with a peak at au and an inferred column density of
cm. A low CHOH fractional abundance of (with respect to H) is derived, depending on the
assumed vertical location of the CHOH molecular layer. In this study, we
use a thermo-chemical model of the TW Hya disc, coupled with the ALCHEMIC
gas-grain chemical model, assuming laboratory-motivated, fast diffusivities of
the surface molecules to interpret the CHOH detection. Based on this disc
model, we performed radiative transfer calculations with the LIME code and
simulations of the observations with the CASA simulator. We found that our
model allows to reproduce the observations well. The CHOH emission in our
model appears as a ring with radius of au. Synthetic and observed line
flux densities are equal within the rms noise level of observations. The
synthetic CHOH spectra calculated assuming local thermodynamic equilibrium
(LTE) can differ by up to a factor of 3.5 from the non-LTE spectra. For the
strongest lines, the differences between LTE and non-LTE flux densities are
very small and practically negligible. Variations in the diffusivity of the
surface molecules can lead to variations of the CHOH abundance and,
therefore, line flux densities by an order of magnitude.Comment: Accepted for publication in MNRAS, 8 pages, 8 figure
Properties of dwarf stars in Cygnus OB2
We present the results of investigation of five stars, originally classified
as dwarfs, belonging to Cyg OB2 association, their stellar and wind properties.
Using both TLUSTY and CMFGEN codes we derived effective temperatures, surface
gravities, chemical abundances, mass-loss rates and projected rotation
velocities. Due to the fact that distance to the stars is well known, we were
able to estimate their luminosities. Using evolutionary models we estimated the
ages of these sample stars and find that lower mass ones - MT282 and MT343 -
belong to older population of the association. Their ages are greater than 10
Myr. The ages of three other stars - MT317, MT299, MT259 - are between 4-6 Myr.Comment: 16 pages, 10 figures, accepted for publication in PAS
Mineral natural table waters as a component of sanatorium-resort children rehabilitation complexes in the remission of oncological diseases
Urgency. High rates of oncological diseases (11.5-12.0 per 10.000 of children's population) dictate the need for comprehensive approaches to the organization of the rehabilitation process. The objective: to justify the advisability of using mineral natural table water in the period of oncopathology remission in children under conditions of sanatorium-and-spa rehabilitation. Materials and methods. The algorithm of the children’s examination included the study of anamnesis, complaints, initial nonspecific adaptive-adaptation reactions (according to the general clinical analysis of blood). The general rehabilitation complex (GRC) included a dose-sparing motion regimen; climatotherapy, diet food, therapeutic exercises in special medical groups, singlet-oxygen cocktail, phytotea (holosas with ascorbic acid), psychological support. In addition to GRC in 2 therapeutic complexes (TC) mineral natural table waters (MW) Truskavetskaya Akva-Eko mineral water (TC1 after treatment of solid tumors) and Morshinskaya (TC2 after treatment of oncohematological diseases). Results. The general tendency to the mend of sick children state under the influence of TC1 was established in comparison with GRC. It manifested in significant changes of various levels (
Economic strategies of russian youth
The article presents the results of the Russian study devoted to the determination of economic dispositions and strategies of modern yout
Lorentzian and signature changing branes
General hypersurface layers are considered in order to describe brane-worlds
and shell cosmologies. No restriction is placed on the causal character of the
hypersurface which may thus have internal changes of signature. Strengthening
the results in our previous letter [1], we confirm that a good, regular and
consistent description of signature change is achieved in these brane/shells
scenarios, while keeping the hypersurface and the bulk completely regular. Our
formalism allows for a unified description of the traditional timelike
branes/shells together with the signature-changing, or pure null, ones. This
allows for a detailed comparison of the results in both situations. An
application to the case of hypersurface layers in static bulks is presented,
leading to the general Robertson-Walker geometry on the layer --with a possible
signature change. Explicit examples on anti de Sitter bulks are then studied.
The permitted behaviours in different settings (-mirror branes,
asymmetric shells, signature-changing branes) are analysed in detail. We show
in particular that (i) in asymmetric shells there is an upper bound for the
energy density, and (ii) that the energy density within the brane vanishes when
approaching a change of signature. The description of a signature change as a
`singularity' seen from within the brane is considered. We also find new
relations between the fundamental constants in the brane/shell, its tension,
and the cosmological and gravitational constants of the bulk, independently of
the existence or not of a change of signature.Comment: 23 pages, 2 figure
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