We present the results of a comprehensive study of four spectroscopic binary Cepheids with long orbital periods. The study makes use of all the available photometric, spectroscopic and astrometric information, and previously developed analysis techniques. The paper is based on a new catalog containing 702 radial velocity measurements of V496 Aql (232 measurements), V1344 Aql (194 measurements), V1334 Cyg (138 measurements), and AW Per (138 measurements). All the measurements were obtained over 1997$\!-\!$2021 on the Zeiss-1000 telescope of the Institute of Astronomy of the Russian Academy of Sciences Simeiz Observatory using the correlation Radial Velocity Meter (RVM) designed by A.A. Tokovinin. Using other published observations, the orbital periods and other orbital parameters were significantly refined: V496 Aql: $P_{\rm orb} \approx 1351\,.\!\!^{\rm d}3\pm0\,.\!\!^{\rm d}7$; V$1344$ Aql: $P_{\rm orb} \approx 6358\pm30{\rm ^d}$; V1344 Cyg: $P_{\rm orb} \approx 1934\,.\!\!^{\rm d}4\pm0\,.\!\!^{\rm d}8$; AW Per: $P_{\rm orb} \approx 13\,663\pm128{\rm ^d}$. Using the mass function, we have found additional constraints on the companion masses and the orientation of the orbital plane. For V496\,Aql and V1344\,Aql, a complete set of astrophysical parameters was found, including the color excess, pulsational radii, luminosity, and mass estimates based on the evolutionary tracks (for V496 Aql, $M \sim 5.6\!-\!5.8 M_\odot$; for V1334 Aql, $M \sim 5.8\!-\!6.0 M_\odot$). For the V1334 Cyg Cepheid with a massive companion, a strong constraint $i \sim 56^\circ\!-\!60^\circ$ on the inclination of its orbital plane was found based on the high mass function. AW Per, with an orbital period of over 37 years and a high mass function, has a companion of a comparable mass. The calculated pulsational radius and luminosity of the Cepheid are in good agreement with the evolutionary mass estimate of $M \sim 5.6\!-\!5.9\,M_\odot$. We show that at inclination angles smaller than $63^\circ\!-\!65^\circ$, the companion can only be a close binary system consisting of two hot stars near the main-sequence turnoff point.
Forecasts of economic indices are important for mitigating the risks of unexpected stresses in the global or local economy. However, the numerous factors that influence the resulting economic index create a complex picture that complicates determining a cyclical pattern. We studied the relationship between solar activity and the Dow Jones Industrial Average from 1896 to 2021. We used correlation and cross-correlation methods with a sliding time window and a wavelet coherency approach to analyze the data. The study revealed that the relationship between the events is not simple and evolves over time. Various synchronization periods, as well as variation in the coherence of these synchronizations over time, were identified. We discovered that the correlation with the 11-year periodicity is greater than 0.5 during the 1906–1936 and 1964–2000 time periods and is visible with a 95 % confidence level during the 1910–1930 and 1990–1994 time periods. This correlation is supported by the found 95 % confidence in the coherence between the cosmic ray data and the Dow Jones index during the same time periods (1964–2000), when the correlation between the sunspot number and this index is high, albeit with other phase differences. Furthermore, the correlation between the cosmic ray data and the Dow Jones is stronger. This could imply that the influence of solar activity on global economy fluctuations is mediated by the Sun’s modulation of cosmic rays.
This paper estimates the kinetic parameters of the fractal stellar medium in the vicinity of the Sun. In this regard, the main stages in the development of ideas about fractal structures in the stellar medium of galaxies are presented. This study is based on investigation of the spatial distribution of 200 000 stars of all spectral types at distances from 1 to 100 pc from the Sun based on the Gaia DR2 data. The results indicate the presence of fractal structures in the solar neighborhood with the fractal dimension D≈ 2.41 . Based on these data, the kinetic properties of the fractal stellar medium are studied. The role of irregular forces and paired stellar encounters in the collisional kinetics of stellar systems is considered. It has been shown that kinetic parameters such as the effective interparticle (interstellar) distance, correlation length, dynamic friction coefficient, and impact parameter for a fractal stellar medium differ significantly from the corresponding parameters for a quasi-homogeneous medium with limited density fluctuations and depend on the fractal dimension. It has been found that the fractal structure of the stellar medium leads to shortening the relaxation time in the Galaxy.
General relativity predicts the existence of an infinite number of nested photon rings around black holes, each containing information about the properties of curved space-time. In this paper, analytical models of a thick Gaussian asymmetric photon ring are developed and the visibility function with baselines up to six Earth diameters is calculated.
During the period of 2023–2026, the scientists of the Special Astrophysical Observatory of the Russian Academy of Sciences (SAO RAS) are implementing a project to create a millimeter-wave observatory based on the BTA optical telescope. The project involves the installation of subterahertz receivers at the Nasmyth focus and the performance of test observations. This paper discusses scientific objectives that can be addressed both at the initial stage of the project using bolometric receivers for continuum observations and, in the future, using receiver systems based on HEMT and SIS technologies for molecular line observations.
