Ionized and neutral gas in the peculiar star/cluster complex in NGC 6946

The characteristics of ionized and HI gas in the peculiar star/cluster complex in NGC 6946, obtained with the 6-m telescope (BTA) SAO RAS, the Gemini North telescope, and the Westerbork Synthesis Radio Telescope (WSRT), are presented. The complex is unusual as hosting a super star cluster, the most massive known in an apparently non-interacting giant galaxy. It contains a number of smaller clusters and is bordered by a sharp C-shaped rim. We found that the complex is additionally unusual in having peculiar gas kinematics. The velocity field of the ionized gas reveals a deep oval minimum, ~300 pc in size, centered 7" east of the supercluster. The Vr of the ionized gas in the dip center is 100 km/s lower than in its surroundings, and emission lines within the dip appear to be shock excited. This dip is near the center of an HI hole and a semi-ring of HII regions. The HI (and less certainly, HII) velocity fields reveal expansion, with the velocity reaching ~30 km/s at a distance about 300 pc from the center of expansion, which is near the deep minimum position. The super star cluster is at the western rim of the minimum. The sharp western rim of the whole complex is plausibly a manifestation of a regular dust arc along the complex edge. Different hypotheses about the complex and the Vr depression origins are discussed, including a HVC/dark mini-halo impact, a BCD galaxy merging, and a gas outflow due to release of energy from the supercluster stars.Comment: MN RAS, accepte

On Tamm's problem in the Vavilov-Cherenkov radiation theory

We analyse the well-known Tamm problem treating the charge motion on a finite space interval with the velocity exceeding light velocity in medium. By comparing Tamm's formulae with the exact ones we prove that former do not properly describe Cherenkov radiation terms. We also investigate Tamm's formula cos(theta)=1/(beta n) defining the position of maximum of the field strengths Fourier components for the infinite uniform motion of a charge. Numerical analysis of the Fourier components of field strengths shows that they have a pronounced maximum at cos(theta)=1/(beta n) only for the charge motion on the infinitely small interval. As the latter grows, many maxima appear. For the charge motion on an infinite interval there is infinite number of maxima of the same amplitude. The quantum analysis of Tamm's formula leads to the same results.Comment: 28 pages, 8 figures, to be published in J.Phys.D:Appl.Phy

Discovery of an unusual bright eclipsing binary with the longest known period: TYC 2505-672-1 / MASTER OT J095310.04+335352.8

We report on the MASTER Global Robotic Net discovery of an eclipsing binary, MASTER OT J095310.04+335352.8, previously known as unremarkable star TYC 2505-672-1, which displays extreme orbital parameters. The orbital period P=69.1 yr is more than 2.5 times longer than that of epsilon-Aurigae, which is the previous record holder. The light curve is characterized by an extremely deep total eclipse with a depth of more than 4.5 mag, which is symmetrically shaped and has a total duration of 3.5 yrs. The eclipse is essentially gray. The spectra acquired with the Russian 6 m BTA telescope both at minimum and maximum light mainly correspond to an M0-1III--type red giant, but the spectra taken at the bottom of eclipse show small traces of a sufficiently hot source. The observed properties of this system can be better explained as the red giant eclipsed by a large cloud (the disk) of small particles surrounding the invisible secondary companion.Comment: 8 figures, 9 pages, Astronomy and astrophysics in prin

Association of ACE gene polymorphisms with cardiovascular events in patients after elective percutaneous coronary interventions

Aim. To reveal the association of the INS/DEL polymorphism of the angiotensinconverting enzyme (ACE) gene with acute and long-term complications of elective percutaneous coronary interventions (PCI).Material and methods. This prospective study included 286 patients with chronic coronary artery disease who underwent elective endovascular myocardial revascularization in accordance with current guidelines. The ACE gene INS/DEL (I/D) polymorphism was determined in patients using polymerase chain reaction. Acute periprocedural complications were recorded. Acute myocardial injury (AMI) was detected in 30,4% of patients. Type 4a acute myocardial infarction developed in 3,1% of patients. A significant decrease in the glomerular filtration rate by more than 30% due to periprocedural acute kidney injury (AKI) was diagnosed in 6,5% of patients. Outcomes of elective PCIs were assessed after 4 years via telephone interviews. Cardiovascular and any-cause mortality was 3,6% and 5,1%, respectively. Acute coronary syndrome during the follow-up period developed in 15,2%, while cerebrovascular accident — in 5,4% of patients. Any-stent thrombosis was detected in 10%, and restenosis ≥30% — in 21,8% of patients. Statistical analysis was carried out using the STATISTICA 10. The odds ratio (OR) was calculated with a 95% confidence interval.Results. Analysis of the association of ACE gene I/D polymorphism with acute and long-term complications of the PCI revealed that the presence of I allele is associated with the risk of periprocedural AKI (p=0,017; OR, 2,627 (1,161- 5,947)), as well as long-term cardiovascular events, vascular complications such as acute coronary syndrome (p=0,045; OR, 1,610 (1,007-2,573)) and stent thrombosis (p=0,01; OR, 2,073 (1,178-3,650)). The presence of genotype II further increases the risk of AKI (p=0,029; OR, 5,138 (1,022-25,824)), any acute clinical complications of PCI (p=0,041; OR, 1,996 (1,024-3,980)), and stent thrombosis (p=0,018, OR, 3,498 (1,178-10,392)).Conclusion. In patients with chronic coronary artery disease, the carriage of allele I and genotype II of the ACE gene I/D polymorphism is associated with the risk of acute clinical complications of elective PCI, periprocedural AKI, as well as the risk of stent thrombosis and acute coronary syndrome within 4-year follow-up period after PCI

The Extremely High Energy Cosmic Rays

Experimental results from Haverah Park, Yakutsk, AGASA and Fly's Eye are reviewed. All these experiments work in the energy range above 0.1 EeV. The 'dip' structure around 3 EeV in the energy spectrum is well established by all the experiments, though the exact position differs slightly. Fly's Eye and Yakutsk results on the chemical composition indicate that the cosmic rays are getting lighter over the energy range from 0.1 EeV to 10 EeV, but the exact fraction is hadronic interaction model dependent, as indicated by the AGASA analysis. The arrival directions of cosmic rays are largely isotropic, but interesting features may be starting to emerge. Most of the experimental results can best be explained with the scenario that an extragalactic component gradually takes over a galactic population as energy increases and cosmic rays at the highest energies are dominated by particles coming from extragalactic space. However, identification of the extragalactic sources has not yet been successful because of limited statistics and the resolution of the data.Comment: The review paper including 21 figures. 39 pages: To be published in Journal of Physics

The Hitting Times with Taboo for a Random Walk on an Integer Lattice

For a symmetric, homogeneous and irreducible random walk on d-dimensional integer lattice Z^d, having zero mean and a finite variance of jumps, we study the passage times (with possible infinite values) determined by the starting point x, the hitting state y and the taboo state z. We find the probability that these passages times are finite and analyze the tails of their cumulative distribution functions. In particular, it turns out that for the random walk on Z^d, except for a simple (nearest neighbor) random walk on Z, the order of the tail decrease is specified by dimension d only. In contrast, for a simple random walk on Z, the asymptotic properties of hitting times with taboo essentially depend on the mutual location of the points x, y and z. These problems originated in our recent study of branching random walk on Z^d with a single source of branching

Solar interacting protons versus interplanetary protons in the core plus halo model of diffusive shock acceleration and stochastic re-acceleration

With the first observations of solar γ-rays from the decay of pions, the relationship of protons producing ground level enhancements (GLEs) on the Earth to those of similar energies producing the γ-rays on the Sun has been debated. These two populations may be either independent and simply coincident in large flares, or they may be, in fact, the same population stemming from a single accelerating agent and jointly distributed at the Sun and also in space. Assuming the latter, we model a scenario in which particles are accelerated near the Sun in a shock wave with a fraction transported back to the solar surface to radiate, while the remainder is detected at Earth in the form of a GLE. Interplanetary ions versus ions interacting at the Sun are studied for a spherical shock wave propagating in a radial magnetic field through a highly turbulent radial ray (the acceleration core) and surrounding weakly turbulent sector in which the accelerated particles can propagate toward or away from the Sun. The model presented here accounts for both the first-order Fermi acceleration at the shock front and the second-order, stochastic re-acceleration by the turbulence enhanced behind the shock. We find that the re-acceleration is important in generating the γ-radiation and we also find that up to 10% of the particle population can find its way to the Sun as compared to particles escaping to the interplanetary space

Spectroscopy of Stellar-Like Objects Contained in the Second Byurakan Survey. I

The results of spectroscopic observations of 363 star-like objects from the Second Byurakan Survey (SBS) are reported. This SBS's subsample has proven to be a rich source of newly identified quasars, Seyfert type galaxies, degenerate stars and hot subdwarfs. In the subsample here studied, we identified 35 new QSOs, 142 White Dwarfs (WDs) the majority of which, 114 are of DA type, 55 subdwarfs (29 of which are sdB-type stars), 10 HBB, 16 NHB, 54 G-type and 25 F-type stars, two objects with composite spectra, four Cataclismic Variables (CV), two peculiar emission line stars, 17 objects with continuous spectra, as well as one planetary nebula. Among the 35 QSOs we have found two Broad Absorption Line (BAL) QSOs, namely SBS 1423+500 and SBS 1435+500A. Magnitudes, redshifts, and slit spectra for all QSOs, also some typical spectra of the peculiar stars are presented. We estimate the minimum surface density of bright QSOs in redshift range 0.3<z<2.2 to be 0.05 per sq. deg. for B<17.0 and 0.10 per sq. deg. for B<17.5.Comment: 22 pages, 3 tables, 4 figures, PASP in pres