Astrophysical Bulletin最新文献

The magnetic field structures of the primary components in threeclose binary systems have been studied. In all their properties,they do not differ from single magnetic stars. There are signsthat the rotational momentum is lost in two ways: 1) it istransferred to the clouds surrounding the magnetic protostar alongthe field lines and 2) through tidal interactions with a closecomponent. Within the hypothesis of the fossil origin of magneticstars, a possible scheme for the formation of close binary systemswith a magnetic companion has been considered.

The regularity/chaoticity of orbits of 45 globular clusters in thecentral region of the Galaxy with a radius of 3.5 kpc, which aresubject to the greatest influence of the elongated rotating bar,is analyzed. Various methods of analysis are used, namely, themethods of calculating the maximum characteristic Lyapunovexponents (MCLE), MEGNO (Mean Exponential Growth factor of NearbyOrbits), the Poincaré section method, the frequency method basedon calculating fundamental frequencies, and a new method isproposed based on calculating the orbit amplitude spectrum as afunction of time and calculating the entropy of the amplitudespectrum as a measure of orbital chaos. Bimodality is found in thehistogram of the distribution of positive Lyapunov exponentscalculated in the classical version, without renormalizing theshadow orbit, which allows implementing a probabilistic method forGC classification, which is also a new approach. To construct theorbits of globular clusters, we used the gravitational potentialmodel with a bar in the form of a triaxial ellipsoid. Thefollowing bar parameters were adopted: mass (10^{10} M_{odot}),length of the semi-major axis 5 kpc, angle of rotation of the baraxis 25({}^{circ}), rotation velocity 40 km s({}^{-1}) kpc({}^{-1}). Toform the 6D phase space required for integrating the orbits, weused the most accurate astrometric data to date from the Gaiasatellite (EDR3), as well as new refined average distances toglobular clusters. Globular clusters with regular and chaoticdynamics were classified. As the analysis showed, globularclusters with small pericentric distances and large eccentricitiesare most susceptible to the influence of the bar and demonstratethe greatest chaos. It is shown that the results of theclassification of globular clusters by the nature of their orbitaldynamics, obtained using the various analysis methods consideredin the work, correlate well with each other.

In this paper, we describe the absorption determination with the(Q)-method for the 2MASS photometry ((J), (H), and (K_{S}) bands).Using the Pleiades and Praesepe stars, we determine thezero-reddening sequence for different values of the color excessratios (E(J-H)/E(H-K_{S})). In this paper, we consider a sequenceconsisting of two segments, that leads to an uncertainty in thedetermining of absorption—one value of the (Q) parametercorresponds to two values of the non-reddened color index. Wepropose a method to select a segment of the zero-reddeningsequence for the main sequence stars of the cluster. The method isbased on the difference in the position of stars of differentsegments in the cluster luminosity function. To test the proposedmethod, we simulate the luminosity functions of clusters with thenon-uniform absorption distribution in the cluster region. Withthe typical absorption values in embedded clusters, about 10(%)of stars are erroneously assigned, but in some cases this fractioncan reach 20(%). Thus, despite the fact that irregular absorptiondistorts the distribution of stars of different segments on thecluster luminosity function, our method allows one to separatestars with an error of no more than 20(%).

We continue to search for and analyze magnetic fields ofchemically peculiar stars in open clusters of different ages. Thepaper presents the analysis of the star clusters Trumpler 37,NGC 2281, and Melotte 111. The observed data were obtained usingthe Main Stellar Spectrograph mounted on the 6-m telescope ofSAO RAS. No CP stars were found in the Trumpler 37 cluster: allsix candidates turned out to be non-magnetic stars with strongemission lines in their spectra. In NGC 2281, we observed only twostars, HD 49040 and HD 49363. Several magnetic stars with weakfields were discovered in the Melotte 111 cluster. As a result, wedid not find stars with a strong (more than 1 kG) longitudinalmagnetic field in any of the studied clusters.

Molecules in the interstellar medium form both in the gas phaseand on dust particles. The chemical pathways for molecularformation are not yet well understood in detail, so the questionof which pathway predominates for a particular molecule remainsopen. We analysed broadband emission spectra of a dense molecularclump in the RCW120 region, obtained with the APEX telescope inthe 200–260 GHz range, to investigate molecular formationpathways in regions of massive star formation at an earlyevolutionary stage. The correlations between the derived molecularcolumn densities, obtained under the LTE assumption, wereinvestigated. An excess of methanol was found in the southern partof the dense clump compared to its northern part, while theabundance of other molecules, such as CH({}_{3})CN and CH({}_{3})CCH,remain comparable. The methanol abundance is also elevatedrelative to other oxygen-bearing molecules, such as OCS and SO. Toidentify possible causes of the enhanced methanol abundance in thesouthern part of the clump, we conducted simulations using theastrochemical model Presta in a two-phase approximation,accounting for chemical processes in both the gas phase and themantles of dust grains. Modeling showed that the enhanced methanolabundance in the gas phase may be due to its photodesorption fromicy mantles. At an (A_{V}) value between (4^{textrm{m}}) and(6^{textrm{m}}), methanol efficiently desorbs from ice mantles ofdust grains upon interaction with photons, but it is not yetdestroyed by UV radiation in the gas phase. A strong linearcorrelation between molecular column densities indicates thatthese molecules form in the same phase—either in the gas phaseor on dust. However, integrated intensity maps of these moleculesmay differ, as seen for CCH and CH({}_{3})CN. If molecules form indifferent phases—one in the gas phase and the other in dustmantles—no correlation is observed, as in the case of CCH andCH({}_{3})OH. The weak correlation between methanol and oxygen-bearingmolecules that form on dust suggests that only the upper part ofthe dust mantles, rich in CO ice, is being destroyed in thesouthern part of the clump.

There is an ongoing need in ground-based astronomy forultra-sensitive receivers, both coherent (e.g., superheterodyne)and incoherent types, the latter offering potentially highersensitivity. Both types rely on superconducting or cryogenicallycooled semiconductor materials. This study explores thefeasibility of using SINIS-based(Superconductor–Insulator–Normalmetal–Insulator–Superconductor) detectors as incoherentsuperconducting receivers. We evaluate the ultimate performanceparameters of SINIS detectors depending on the choice ofsuperconducting material, operating temperature, and detectionregime. Under moderate sub-Kelvin cooling (down to (0.28) K),aluminum-based SINIS detectors may achieve a responsivity of up to(10^{8}) V W({}^{-1}) and a noise-equivalent power(text{NEP}=10^{-17}) W Hz({}^{-1/2}). For niobium-based SINISdetectors operating at 4.2 K, our estimates yield an(text{NEP}=1.6times 10^{-16}) W Hz({}^{-1/2}), which may be ofpractical interest for specific applications. At the SpecialAstrophysical Observatory of the Russian Academy of Sciences (SAORAS), a prototype project is underway to develop a domesticsubterahertz observatory module integrated with the Big TelescopeAlt-azimuthal (BTA). Within this framework, a SINIS-basedsubterahertz receiver is planned to be installed at the Nasmythfocus of the BTA optical telescope. This paper provides atechnical overview and proposed design of the SINIS receiver,taking into account the optical telescope’s reflective systemarchitecture, its immediate environment, and the expectedscientific goals of such an observational setup.

This paper presents a review of 67 scientific publications from2024 devoted to stellar magnetism and related topics. The primaryfocus of recent research lies in the discovery of new magneticstars and the monitoring of magnetic fields in chemically peculiar(CP) stars and other stellar types. Interest in the study ofmagnetic star emission in the X-ray and radio domains has alsoincreased. The most significant new data were obtained using Gaiaastrometry, TESS and Kepler photometry, and LAMOST low-resolutionspectroscopy. The first results from the new SPIRou and CRIRES+spectrographs are also discussed.

Numerous methods have been tried and many more are currently beingattempted to discover technosignatures of intelligentcivilizations. One thing is for sure: an existing technosignaturewould modify its environment in detectable ways. The current studyhas investigated all possible voluntary and involuntarytechnosignatures, ranging from beacons to Dyson megastructures andfrom self-replicating probes to the still hypothetical stellarengines, in order to determine the extent to which thesetechnosignatures would reveal themselves within a specified finitesphere 500 light years across, corresponding to nearly half theaverage thickness of our Galaxy. We then estimated theprobabilities of detection of such technosignatures based on theregions, or domains, they would produce and investigated whetheror not a correlation exists with the position of civilizations onthe Kardashev scale. The study further explored which ones of thevoluntary and involuntary technosignatures have higher detectionprobabilities.

The results of the latest study of the thermal evolution featuresof white dwarfs with large surface magnetic fields are presented.The main objective of the work is to test the hypothesis that forcooling degenerate stars—white dwarfs (WD)—the stopping ofexternal convection by a magnetic field greater than one megagausssignificantly slows down their cooling. For this purpose, theobserved luminosity function of WDs with surface fields greaterthan one megagauss is constructed in a volume with a 20 pc radius20 pc and compared to the known similar luminosity function of allWDs, regardless of their magnetic field values. The generaltendency—a significant increase in the frequency of occurrenceof magnetic white dwarfs (MWDs) with an increase in their absolutebolometric magnitude (a decrease in brightness) is confirmed.Empirical modeling of the effect of magnetically inducedsuppression of convection on the luminosity function of stronglymagnetized WDs also showed an increase in their frequency withage, although with a shift of one stellar magnitude toward weakermagnitudes. This shift is a consequence of the imperfection of themodel. The effect of an increase in the frequency of occurrence ofstrongly magnetized WDs with age cannot be explained either by asystematic difference in the masses of magnetic and non-magnetic(with magnetic fields below the detection limit) WDs, or by thepeculiarities of their formation rates in different epochs.

We present the results of the development and commissioning of the60-cm RoboPhot telescope at the Kourovka Astronomical Observatoryequipped with the TRIP three-channel photometer (Three-channelRoboPhot Imaging Photometer). The photometer is designed forsimultaneous imaging in three bands of the SDSS photometricsystem: (g), (r), and (i). Currently, it is equipped with only twoCCD cameras with a resolution of (2048times 2048) pixels, a fieldof view of (22^{prime}times 22^{prime}), and an image scale of(0overset{primeprime}{.}65) pixel({}^{-1}). The primaryobjective of the telescope is high-precision multicolordifferential photometry of asteroids and variable stars,particularly exoplanet transits. For stars with a magnitude of(13overset{textrm{m}}{.}5), a differential photometry precision(rms) of 2.5 ppt in magnitudes is achieved with a120({}^{textrm{s}}) exposure. The telescope is expected to becomethe leading instrument at the Kourovka Observatory for exoplanetstudies and contribute to the TESS research program.