Abstract In this paper, the results of observations of the magnetar SGR 1935+2154 at a frequency of 111 MHz with the BSA LPI radio telescope in the period from April 2021 to November 2024 have been presented. To search for both periodic and single pulses, data from six frequency channels with a time resolution of 0.1 s, which are recorded in the reception band of $$(110.25 \pm 1.25)$$ MHz, have been used. During data processing for the specified period, the upper limit, 250 mJy, of radio emission of the magnetar SGR 1935+2154 at a frequency of 111 MHz has been estimated.

Abstract Numerical simulations of the evolution of the Solar system consisting at the initial stage of five, six, seven, and eight outer planets, as well as a self-gravitating planetesimal disk, were carried out. The dynamical evolution of planetary systems was studied over a time interval of 4 Gyr. In most cases of numerical simulations, either the destruction of planetary systems or the transition of planets to orbits significantly different from modern orbits occurred. However, a number of successful variants, in which the configuration of the orbits of the outer planets after 4 Gyr was close to the present Solar system, were found. The ejection of additional planets can occur at all stages of the evolution of the Solar system. In the variant with eight planets, a case of an additional planet remaining in a distant trans-Neptunian orbit with a perihelion distance of q = 120 AU was found. Despite the great diversity of evolutionary paths of systems with additional planets, distant trans-Neptunian objects were registered in all successful variants. A trend towards an increase in the number of surviving distant trans-Neptunian objects with an increase in the number of additional planets was noted.

Abstract In the paper, archival data of the RadioAstron ground–space interferometer project concerning observations of radiation in the OH hydroxyl lines (1665 and 1667 MHz transitions) in the Cep A source have been analyzed. The observations have been carried out on January 7, 2013. The duration of the observation session was about one hour. Ground-based radio telescopes at the Zelenchuk Observatory (Special Astrophysical Observatory of the Russian Academy of Sciences, North Caucasus, Russian Federation), in Yevpatoria (Crimea, Russian Federation), and at the Torun Astronomy Center (Republic of Poland) have participated in the observations. No interferometric response has been detected at the ground–space bases. Several compact sources with angular sizes from 10 to 20 milliarcseconds have been detected at the base between the radio telescopes in Torun and at the Zelenchuk Observatory. These angular sizes correspond to linear sizes of 7.5–15 astronomical units (AU). It has been shown that the detected compact sources are distributed over a region of 750–1500 AU.