ALBERT

Description: To study phenomenological properties of extensive air showers initiated by different particles (i.e., γ , p , Fe), CORSIKA simulations were used. We adopted a statistical method to produce diagrams of mean values of depth of shower maxima, 〈 X max 〉, versus energy decades. To be compared with other works, this method were applied for Yakutsk array and the resulted diagrams were used to calculate the mass composition of a set of published data from this array. The mass composition of cosmic rays (from 10 17 eV up to the highest energies) in different combinations ofQGSJET-II-04, SYBILL 1.6, and SYBILL 2.1 with FLUKA were discussed and upper limits for the observed proton flux were calculated. Due to these results a tendency to light nuclei was proposed and the predicted value of upper limit for the observed proton flux was close to GZK cutoff in a combination of FLUKA and QGSJET-II-04 models.

Description: The identification of the X-ray 3.55-keV line as a recombination line of the π − tritium mesoatom is proposed. The formation of such an atom under standard astrophysical conditions without invoking new physics is shown to be possible in principle.

Description: Using two volume-limited Main galaxy samples of the Sloan Digital Sky Survey Data Release 10 (SDSS DR10), we study u-band luminosity dependence of galaxy clustering by cluster analysis. Statistical results of two volume-limited Main galaxy samples are the same: luminous galaxies in M u preferentially form isolated galaxies, close pairs and small groups at all scales, whereas faint galaxies in M u preferentially inhabit dense groups and clusters.

Description: Based on masers with measured trigonometric parallaxes, we have redetermined the spatial orientation parameters of the Local (Orion) arm. Using 23 sources (the Gould Belt objects were excluded), we have found that their spatial distribution can be approximated by a very narrow ellipsoid elongated in the direction L 1 = 77.1° ± 2.9° whose symmetry plane is inclined to the Galactic plane at an angle of 5.6° ± 0.2°. The longitude of the ascending node of the symmetry plane is \(l_\Omega = 70^\circ \pm 3^\circ \) . A newestimate for the pitch angle of the Local spiral arm has been obtained by an independent method: i = 12.9° ± 2.9°. Previously, a belt of young B stars, the de Vaucouleurs-Dolidze belt, was pointed out on the celestial sphere with parameters close to such an orientation. We have refined the spatial orientation parameters of this belt based on a homogeneous sample of protostars. The de Vaucouleurs-Dolidze belt can be identified with the Local arm, with the belt proper as a continuous band on the celestial sphere like the Gould Belt being absent due to the peculiarities of the spatial orientation of the Local arm. Using the entire sample of 119 Galactic masers, we have shown that the third axis of their position ellipsoid has no deviation from the direction to the Galactic pole: B 3 = 89.7° ± 0.1°.

Description: Based on data on Galactic masers with measured trigonometric parallaxes, we have tested a nonlinear model of Galactic rotation using generalized Oort formulas. This model is shown to yield pretty good results up to heliocentric distances of 3–4 kpc. The main feature of the method is the possibility of estimating the solar Galactocentric distance R 0 . This distance has been found by analyzing ≈60 masers to be R 0 = 8.3 ± 0.4 kpc. Our study of the three-dimensional kinematics of more than 100 masers based on the Ogorodnikov-Milne model has shown that significant nonlinearities are present only in the xy plane (rotation around the Galactic z axis) due to the peculiarities of the Galactic rotation curve. No significant linear dependences have been found in the xz and yz planes. We show the presence of a wave in the velocities w as a function of coordinate x or distance R with a wavelength of ∼3 kpc and an amplitude of ∼10 km s −1 . The wave is particularly prominent in the Local and Perseus arms.

Description: Based on high-resolution spectra taken with the 1.9-m telescope of the South African Astronomical Observatory, we have determined the atmospheric parameters and chemical composition for three small-amplitude (AV Cir, BP Cir, and LR TrA), two classical (R TrA and S TrA), and one double-mode (U TrA) Cepheids. The averaged atmospheric parameters have been estimated for three Cepheids (AV Cir, BP Cir, and U TrA) observed at various pulsation phases. In all Cepheids, except U TrA, the metallicity has turned out to be higher than the solar one by 0.1–0.2 dex. The abundances of the key elements of the evolution of yellow supergiants (C, O, Na, Mg, Al) show that these objects have already passed the first dredge-up, while those of the remaining elements are nearly solar. Comparison of our results on the Cepheids from the list (except U TrA) with those of other authors shows significant differences in C and O abundance estimates for AV Cir, R TrA, S TrA, and LR TrA. For AV Cir and BP Cir, the H α line profiles are symmetric but with a slight asymmetry in the core at approximately the same phase near 0 · P 7: on the “blue” side for AV Cir and on the “red” one for BP Cir. BP Cir exhibits a distinct asymmetry in the absorption lines of neutral atoms and ions at various pulsation phases, which can be explained by nonradial first-overtone pulsations. The constancy of the H α absorption line profiles with pulsation phase for AV Cir and BP Cir may suggest the presence of a hydrogen envelope around them. For the double-mode Cepheid U TrA, an asymmetry is observed in the cores of the H α line and the absorption lines of neutral atoms and ions at various pulsation phases, which can be explained by nonradial pulsations in the Cepheid’s atmosphere. The absorption lines of neutral atoms and ions of metals in LR TrA closely resemble those in the well-known Cepheid BG Cru: secondary “blue” and “red” components whose line depths vary with pulsation phase are noticeable. This Cepheid can also pulsate in the first overtone and have an extended hydrogen envelope. Careful multiphase spectroscopic observations with a sufficiently high resolution are needed to test this assumption.

Description: The fine structure of the nucleus of the radio galaxy M 87 has been investigated at wavelengths of 2 and 3 cm. Its kinematics is determined by the inflow of the surrounding thermal plasma onto the “accretion disk, ” its transfer in a spiral to the center, and its ejection as a bipolar outflow carrying away an excess angular momentum as it is accumulated. The remainder of the material falls to the central massive body, a black hole. Ring currents, magnetic fields, are generated in the rotating disk and the bipolar outflow. The visible structure is determined by the synchrotron radiation of the relativistic electrons passed through the surrounding magnetoactive plasma that rotates the polarization plane. The regular component of the rotation measure reaches 10 4 rad m −2 toward the center of the core structure and decreases exponentially to zero in the counterjet at a distance of 0.15 pc from the ejector. In the jet, starting from a distance of 0.2 pc, the decrease slows down and corresponds to RM = 200 rad m −2 at a distance of 0.5 pc. The shift of the regular component of the rotation measure by ∼40 mpc toward the jet is determined by the disk inclined in this direction. Excesses of the rotation measure by ∼2000 rad m −2 are observed at the locations of the bright fragments in the flows and are associated with their magnetic field. The parameters of the surrounding medium, the screen, are L = 0.05–0.5 pc, N e ≈ 10 5 cm −3 , and B ‖ = 200–500 mG. The longitudinal magnetic field is directed toward the observer.

Description: When electrons are accelerated to relativistic energies in the inner gap of a pulsar, their motion is quantized in an external magnetic field and the electric field of the space charge of a rotating electron beam, an electromagnetic tornado appearing during breakdown in the pulsar’s polar gap. Quantization allows one to propose a natural explanation for the observed bands in the frequency spectrum of interpulse radiation from the pulsar PSR J0534+22 in the Crab Nebula and to determine the physical parameters of the tornado. The difference in the spectra of main pulses and interpulses is discussed.