254 research outputs found

    Long term variability of the Broad Emission Line profiles in AGN

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    Results of a long-term monitoring (10\gtrsim 10 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 Hα\alpha and Hβ\beta 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

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    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

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    The recent detection of gas-phase methanol (CH3_3OH) 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 3050\sim 30-50 au and an inferred column density of 36×1012\sim 3-6\times10^{12} cm2^{-2}. A low CH3_3OH fractional abundance of 0.34×1011\sim 0.3-4\times 10^{-11} (with respect to H2_2) is derived, depending on the assumed vertical location of the CH3_3OH 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 CH3_3OH 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 CH3_3OH emission in our model appears as a ring with radius of 60\sim60 au. Synthetic and observed line flux densities are equal within the rms noise level of observations. The synthetic CH3_3OH 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 CH3_3OH 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

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    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

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    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

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    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

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    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 (Z2Z_{2}-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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