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Vol 102, No 4 (2025)
Articles
OBSERVING OF BACKGROUND ELECTROMAGNETIC RADIATION OF THE REAL SKY THROUGH THE THROAT OF A WORMHOLE
Abstract
The numerical investigation conducted in this paper addresses the problem of CMB radiation imaging as seen through the throat of the Ellis-Bronnikov-Morris-Thorne wormhole. It is assumed that both throats of the wormhole are relatively close to our stellar neighborhood, so close that the view of the ambient background radiation by an observer at the other throat of the wormhole is virtually identical to that seen from the Solar System neighborhood. A map of the temperature distribution of the cosmic microwave background radiation observed through the mouth of the wormhole has been constructed as well as a view of the Milky Way through the mouth of the wormhole. The resultant image contains characteristic details that enable it to be distinguished from an image produced by a black hole.
Astronomičeskij žurnal. 2025;102(4):239–249
239–249
RADIOINTERFEROMETRIC OBSERVATIONAL CAPABILITIES OF RELATIVISTIC JETS IN ACTIVE GALACTIC NUCLEI FOR THE “MILLIMETRON”
Abstract
The paper presents the analysis of observational capabilities of the Millimetron observatory’s very-long- baseline radio interferometry mode for active galactic nuclei to obtain two-dimensional images of these objects with high angular resolution. The observatory, with its 10-meter mirror, will conduct observations in the very long baseline radio interferometry mode together with ground telescopes in the frequency range of 43–345 GHz (wavelength range of 7–0.7 mm). Due to the orbit in the vicinity of the L2 Lagrange point of the Sun-Earth system, the maximum angular resolution will be up to 0.8 (43 GHz), 0.4 (100 GHz), 0.14 (230 GHz) and 0.1 (345 GHz) microarcseconds. Obtaining images with high angular resolution not only allows one to study the vicinity of nearby supermassive black holes, but also opens up new possibilities in studying the structure and dynamics of relativistic jets of active galactic nuclei and investigating the core shift effect. Based on the previously calculated nominal orbit for the Millimetron observatory, an analysis of the observational capabilities of 379 sources previously observed within the Radioastron mission scientific program was performed. The fundamental capabilities of obtaining radio images of 13 sources with a specific possible time and duration of such observations were demonstrated. The obtained results have broad practical significance in terms of further planning and development of the scientific program for the space-ground interferometer mode of the Millimetron observatory.
Astronomičeskij žurnal. 2025;102(4):250–261
250–261
STUDY OF THE PHYSICAL AND CHEMICAL PROPERTIES OF DENSE CLUMPS AT DIFFERENT EVOLUTIONARY STAGES IN SEVERAL REGIONS OF MASSIVE STAR AND STELLAR CLUSTER FORMATION
Abstract
Massive stars play an important role in the Universe. Unlike low-mass stars, the formation of these objects located at great distances is still unclear. It is expected to be governed by some combination of self-gravity, turbulence, and magnetic fields. Our aim is to study the chemical and physical conditions of dense clumps at different evolutionary stages. We performed observations towards 5 regions of massive star and stellar cluster formation (L1287, S187, S231, DR 21(OH), NGC 7538) with the IRAM-30m telescope. We covered the 2 and 3–4 mm wavelength bands and analysed the lines of HCN, HNC, HCO+, HC3N, HNCO, OCS, CS, SiO, SO2, and SO. Using astrodendro algorithm on the 850 μm dust emission data from the SCUBA Legacy catalogue, we determined the masses, H2 column densities, and sizes of the clumps. Furthermore, the kinetic temperatures, molecular abundances, and dynamical state were obtained. The Red Midcourse Space Experiment Source survey (RMS) was used to determine the clump types. A total of 20 clumps were identified. Three clumps were found to be associated with the H II regions, 10 with young stellar objects (YSOs), and 7 with submillimetre emission. The clumps have typical sizes of ∼ 0.2 pc and masses from 1 to 102 𝑀⊙, kinetic temperatures of ∼ 20 − 40 K and line widths of H13CO+ (1–0) ∼ 2 km/s. We found no significant correlation in the line “width-size” and the “line width-mass” relationships. However, a strong correlation is observed in “mass-size” relationships. The virial analysis indicated that three clumps are gravitationally bound. Furthermore, we suggested that significant magnetic fields, ∼ 1 mG, provide additional support for clump stability. The molecular abundances (relation to H2) are ∼ 10−10 − 10−8.
Astronomičeskij žurnal. 2025;102(4):262–280
262–280
STUDY OF MASER AND THERMAL MOLECULAR EMISSION IN THE VICINITY OF SELECTED PROTOSTELLAR OBJECTS WITH THE RT-22 RADIO TELESCOPE AT PRAO
Abstract
At the early stage of the protostar existence, gas is mostly in molecular form, and the process of protostars development causes a variety of surrounding matter emission in molecular lines at many frequencies in any diapason. The goal of this work is to measure molecular radio lines parameters in the vicinity of some young protostar objects to improve the understanding of their evolutionary trends. Observations were carried out with the RT-22 radio telescope of the Pushchino Radio Astronomical Observatory of the Lebedev Physical Institute from July 2022 until May 2023. Two standard transistor receivers were used, which operated at frequencies of 20–24 GHz (range 13.5 mm) and 36.2–37.7 GHz (range 8 mm). We studied emission in the lines of four molecules, each one being a “tracer” of the environmental physical state: water (H2O), methanol (CH3OH), ammonia (NH3) and cyanoacetylene (HC3N). Observational results were obtained for three IRDC objects, for two CORE-type objects and for the star forming region Onsala-1. Radio emission in the water vapor line was detected in all studied objects, except for IRDC G027.94–00.47. For three objects: IRDC G028.37+0.07b, IRDC G024.33+0011 and Onsala-1, the rotational and kinetic temperatures in the radiation region were determined from the emission spectra of the ammonia molecule, and estimates of the concentration of ammonia and the density of molecular hydrogen were obtained. Emission in lines of cyanoacetylene was detected in the direction of to sources IRDC G028.37+0.07b and Onsala-1, and the column density of this molecule was determined.
Astronomičeskij žurnal. 2025;102(4):281–297
281–297
APSIDAL MOTION AND PHYSICAL PARAMETERS OF V361 CAM
Abstract
Our multicolour photometric measurements ofV361 Cam (P = 8.64d, V = 10.79m, e = 0.12, B5 IV+B9 V) over the past 16 years, as well as TESS data, allowed us to determine for the first time the main physical characteristics of the system and measure the apsidal rotation velocity. The following physical parameters of the component stars were obtained: T1 = 15 400 ± 300 K, M1 = 6.0 ± 0.4 MQ, R1 = 5.03 ± 0.05 Ro, T2 = 11700 ± 250 K, М2 = 2.8 ± 0.2MQ, R2 = 1.94 ± 0.04RQ. The photometric parallax of 0.00035" ± 0.000001" matches the Gaia measurement of 0.00035" ± 0.00003". The apsidal rotation velocity is wobs = 0.024 ± 0.007°/year, which is less than the theoretical value underthe synchronism condition wtheor = 0.056 ± 0.006°/year. The age of the system, assuming solar chemical composition, is 70 Myr. Both components are pulsating в Cephei variables.
Astronomičeskij žurnal. 2025;102(4):298–316
298–316
SPECTROSCOPIC BINARY CEPHEID AU PEG IN GAIA DR3 EPOCH: THE ELLIPSOIDALITY EFFECT, MASS AND EVOLUTIONARY STATUS
Abstract
The physical parameters and evolutionary status of the spectroscopic binary Cepheid AU Peg, usually classified as a BL Her variable, are revised. Taking into account previously unpublished radial velocity measurements made with the correlation spectrometer, the parameters of the relative orbit of the system are refined. Based on 74 new radial velocity measurements made in the period 𝐽𝐷 2453930 − 2459490 almost simultaneously with the photometric observations of Gaia DR3 (44 brightness measurements in the period 𝐽𝐷 2456962 − 2457877), the parameters of to orbit and the radius of AU Peg is determined by the pulsating photosphere method to be ((16.0 ± 0.6) 𝑅⊙, with the amplitude of radius variations is about 0.7 𝑅⊙. For the first time, brightness variations at the level of 2% in the 𝐺 band with a half orbital period were found for spectroscopic binary Cepheids, the phases of which are clearly synchronized with the phases of the orbital motion (conjunctions and quadratures) and can be interpreted as a manifestation of the effect of the ellipsoidality of the primary component, filling the Roche sphere by 60–70%. The orbit of the binary system, calculated on the basis of astrometric data from Gaia DR3 and radial velocities, is bounded by a torus with a thickness of S𝑧S ⩽ 300 pc and inner and outer radii equal to 7.2 and 8.8 kpc, respectively, while the vertical velocity lies within S𝑉𝑧S ⩽ 18 km/s. Based on its kinematics and abundance of heavy elements, AU Peg can certainly be classified as a representative of the typical population of a disk of moderate (∼ 1–3 billion years) age, which completely excludes its classification as a BL Her variable. The Cepheid, whose current mass, as follows from the magnitude of the ellipsoidality effect, does not exceed ∼ (0.85 ± 0.05) 𝑀⊙, is at the stage after the mass exchange in the subgiant phase with a companion — a main sequence star, which is currently significantly more massive than the Cepheid.
Astronomičeskij žurnal. 2025;102(4):317–330
317–330
INFLUENCE OF AMBIENT CONDITIONS AND DUST PARAMETERS ON THE THERMAL DESORPTION RATE OF ICE MANTLE
Abstract
In this work, we present the calculations of dust temperature and thermal desorption rates in cold molecular clouds with taking into account the stochasting heating of dust grains by ultraviolet (UV) radiation field and cosmic rays (CRs) including secondary electrons. The calculations were carried out for dust grains with radius of their core within the range from 0.005 to 0.25 ?m. Silicate and graphite grains covered by ice mantle (H2O) with thickness corresponding to the volume proportions Sil/Gra : H2O = 3:1 and 1:1 were considered. For each dust composition, the closest physical properties (heat capacity, absorption cross sections, stopping power) were used. Thermal desorption rates vary up to several orders depending on dust size and up to factor of 2 depending on the position in a cloud and dust core material. The obtained thermal desorption rates differ from the estimates available in literature up to 2 orders depending on dust size and outer conditions.
Astronomičeskij žurnal. 2025;102(4):331–340
331–340
VARIATION OF GLOBAL AND LOCAL FLOWS IN THE SOLAR CONVECTION ZONE DURING ACTIVITY CYCLES 24 AND 25
Abstract
Convection, differential rotation, and meridional circulation of solar plasma are studied based on helioseismic data covering the period from May 2010 to August 2024, significantly prolonged compared to that previously considered. Depth variation in the spatial spectrum of convective motions indicates a superposition of differently scaled flows. The giant-cell-scale component of the velocity field demonstrates a tendency to form meridionally elongated (possibly banana-shaped) structures. The integrated spectral power of the flows is anticorrelated with the solar-activity level in the near-surface layers and positively correlates with it in deeper layers. An extended 22-year cycle of zonal flows (“torsional oscillations” of the Sun) and variations of the meridional flows are traced. A secondary meridional flow observed at the epoch of the maximum of Solar Cycle 24 to be directed equatorward in the subsurface layers is clearly manifest in Cycle 25.
Astronomičeskij žurnal. 2025;102(4):341–354
341–354