Astrophysical Bulletin最新文献

{"title":"Programmable Radiometer-noise Model with Random Drift Contribution","authors":"V. N. Chernenkov","doi":"10.1134/S199034132360045X","DOIUrl":"10.1134/S199034132360045X","url":null,"abstract":"<p>A method for radiometer-noise generation and its software implementation in the form of a Python library module is proposed. The method can be used to simulate radiometer noise with variable component properties: Gaussian white noise and flicker noise (random drift) with a power spectrum linearly increasing with decreasing frequency. The method is based on the transformation of spectral properties of Gaussian noise via sequential filtering by a differentiator, nonlinear threshold switch, and subsequent integration. By changing the integrator accumulation time constant and the threshold level relative to noise intensity <span>(sigma)</span> one can change the resulting form of the spectrum and the corresponding statistical parameters of the output noise over a wide range: from stationary white noise to noise dominated by a <span>(1/f)</span>-type spectrum component. Empirical polynomial approximation formulas for the dependence of the spectral index of the resulting noise records on the nonlinear threshold switch level in the 0.0–<span>(3.5sigma)</span> interval are derived based on numerical simulations using a software implementation of the model. Examples of noise-record implementations, their spectra, and autocorrelation functions are demonstrated. The generated noise is shown to be similar to the noise observed on radio telescopes of the Institute of Applied Astronomy of the Russian Academy of Sciences.</p>","PeriodicalId":478,"journal":{"name":"Astrophysical Bulletin","volume":"79 1","pages":"167 - 173"},"PeriodicalIF":1.3,"publicationDate":"2024-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140932458","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cases of Further Integrability of the Equation of Motion in the Presence of the Local Integral in the Space Model. I","authors":"F. T. Shamshiev","doi":"10.1134/S1990341323600308","DOIUrl":"10.1134/S1990341323600308","url":null,"abstract":"<p>A local integral that allows us to immediately determine the velocity field for certain specific initial conditions was introduced by Antonov and Shamshiev in 1992. We consider cases where the integrability of the trajectory can be advanced further. We then obtain an analytical relationship between <span>(x)</span>, <span>(y)</span>, <span>(z)</span>, <span>(t)</span> on a given trajectory. Possible cases are classified and one of them is analyzed.</p>","PeriodicalId":478,"journal":{"name":"Astrophysical Bulletin","volume":"79 1","pages":"151 - 158"},"PeriodicalIF":1.3,"publicationDate":"2024-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140932544","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Metallicity of Young Stars of the NGC 4068 Galaxy","authors":"N. A. Tikhonov","doi":"10.1134/S1990341323600023","DOIUrl":"10.1134/S1990341323600023","url":null,"abstract":"<p>Based on archival images from the Hubble Space Telescope, stellar photometry of the galaxy NGC 4068 was carried out. The resulting Hertzsprung-Russell diagram (CM diagram) shows branches of young and old stars. To estimate the metallicity of young stars, isochrones of different ages and metallicities were used. A combination of isochrones and the CM diagram of stars shows that the young stars of NGC 4068 have high metallicity, up to the metallicity of the Sun (<span>(Z=0.02)</span>). Since stars of high metallicity are observed throughout the body of the galaxy, we can talk about high metallicity of the entire galaxy, and not just one local region. The position of NGC 4068 among 105 irregular galaxies of different metallicities is shown on a diagram of the dependence between the metallicities of old and young stars. The almost linear dependence between these parameters indicates the absence of processes of rapid enrichment of galaxies with metals at the present stage of their evolution. The obtained results do not confirm the conclusion about the low metallicity of NGC 4068 reported earlier. For direct measurements of the metallicity of NGC 4068, the coordinates and fields of identification of the three brightest red supergiants with a high color index <span>((V-I))</span>, which indicates their high metallicity, are presented.</p>","PeriodicalId":478,"journal":{"name":"Astrophysical Bulletin","volume":"79 1","pages":"25 - 35"},"PeriodicalIF":1.3,"publicationDate":"2024-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140934728","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Metron Project—I. The Metron Project Science Program","authors":"V. K. Dubrovich,&nbsp;S. I. Grachev,&nbsp;Yu. N. Eroshenko,&nbsp;S. I. Shirokov,&nbsp;G. G. Valyavin","doi":"10.1134/S1990341324600030","DOIUrl":"10.1134/S1990341324600030","url":null,"abstract":"<p>In this paper, the first in a series of four articles, the scientific goals of the Metron project are highlighted, and the characteristics of the cosmic objects available for study within its framework are provided. The Metron interferometer radio telescope should include arrays of meter-range dipole antennas placed on Earth, in outer space, or on the far side of the Moon (or a combination of these options). Working in the meter range will enable the study of the so-called cosmological epoch of the ‘‘Dark Ages’’, which is challenging to observe but highly interesting for understanding the origin of the first stars, galaxies, and black holes, as well as for the search for new cosmological objects and processes. One possibility is to search for absorption in the 21-cm line within the extended halos around early protogalaxies and supermassive primordial black holes, whose existence is predicted in a number of models. Another goal of Metron may be to clarify the anomalous absorption in the 21-cm line previously detected by the EDGES telescopes and to observe radio emissions from the magnetospheres of stars and exoplanets. The Metron project aims to achieve unprecedented resolution in the meter range, which is expected to yield new world-class scientific results. Meter-range antennas and receivers are relatively simple and inexpensive, and the construction of interferometric arrays from them can be accomplished in a relatively short period of time.</p>","PeriodicalId":478,"journal":{"name":"Astrophysical Bulletin","volume":"79 1","pages":"159 - 166"},"PeriodicalIF":1.3,"publicationDate":"2024-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140932535","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Radio Sources of the Survey on the Declination\u0000of the Pulsar in the Crab Nebula ((mathbf{Dec}boldsymbol{=+22}^{boldsymbol{circ}}))","authors":"A. A. Kudryashova,&nbsp;N. N. Bursov,&nbsp;S. A. Trushkin","doi":"10.1134/S1990341324700263","DOIUrl":"10.1134/S1990341324700263","url":null,"abstract":"<p>The results of the analysis of 205 brightest sources (<span>(S&gt;15)</span> mJy),\u0000which were found in the sky survey at the declination of the\u0000pulsar in the Crab Nebula, are presented. The survey was conducted\u0000at a frequency of 4.7 GHz using a three-beam radiometer complex\u0000installed in the focus of the Western Sector of the RATAN-600\u0000radio telescope in 2018–2019. Based on the measurements taken and\u0000the data collected in the CATS astrophysical catalogs database,\u0000the radio spectra of the objects were constructed. For a quarter\u0000of all detected sources, data at frequencies above 4 GHz were\u0000obtained for the first time, and for the rest they were\u0000supplemented. The variability of radiation sources on the scales\u0000of the year, from days to months, has been studied. The greatest\u0000change in the radio flux was found in the blazar B2 1324<span>(+)</span>22. The\u0000search for daily variability was carried out for 26 of the\u0000brightest sources with an average value of <span>(S_{4.7}sim 250)</span> mJy.\u0000All sources are identified with objects from\u0000optical and infrared catalogs. The radio luminosity was calculated\u0000for 112 objects with known redshifts.</p>","PeriodicalId":478,"journal":{"name":"Astrophysical Bulletin","volume":"79 1","pages":"36 - 59"},"PeriodicalIF":1.3,"publicationDate":"2024-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140932538","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"On Estimating the Masses of Star Clusters Embedded in Clouds of Interstellar Gas and Dust","authors":"V. M. Danilov","doi":"10.1134/S1990341323600321","DOIUrl":"10.1134/S1990341323600321","url":null,"abstract":"<p>In the article, a method is developed for estimating the dynamic masses of the stellar and gas components of cluster-cloud systems under conditions of non-isolation and significant non-stationarity of stellar and gas subsystems in a regular field. A number of estimates of the dynamic masses of the stellar and gas components of the system are made without using the virial theorem for zero and positive values of the total energies <span>(E)</span> of the system as a whole and <span>(E_{2})</span> of its gaseous subsystem. The well-known estimates of the free-fall time <span>(tau_{textrm{ff}})</span> for fragments in the force field of a sphere of uniform and inhomogeneous density sphere simulating a system of gas and stars are refined. The estimates of the <span>(tau_{textrm{ff}})</span> quantities are supplemented by estimates of the radial velocities <span>(v_{r})</span> of the fragments in such systems. A number of relations between the parameters of the stellar and gas subsystems in the considered models of embedded clusters are obtained. It is shown that instead of one virial coefficient to describe the system, it is necessary to use three coefficients, the formulas for which are given. The relations make it possible to estimate the dynamic masses of non-isolated and non-stationary subsystems from data on the structural-dynamic characteristics of an embedded cluster. It is shown that the ratio <span>({overline{v}}_{c,1}^{2}/sigma_{1,v}^{2}&gt;4)</span>, where <span>(sigma_{1,v}^{2})</span> is the mean square of the velocities of the stellar subsystem in the case of its virial equilibrium, and <span>({overline{v}}_{c,1}^{2})</span> is the mean square of the critical velocities of the stars in this subsystem. It is shown that embedded clusters with parameters <span>(x=R_{1}/R_{2})</span> and <span>(mu=M_{1}/M_{2})</span> have maximum values <span>({overline{v}}_{c,1}^{2}/sigma_{1,v}^{2})</span> along some curve in the <span>((x,mu))</span> space (<span>(M_{i})</span> and <span>(R_{i})</span> are the mass and radius of the <span>(i)</span>th subsystem). The embedded clusters with parameters <span>((x,mu))</span> close to this curve are the least susceptible to destruction space relaxation processes. It is shown that, depending on the initial energies <span>(E)</span> and <span>(E_{2})</span>, the masses of a subsystem of stars in an embedded cluster can be much smaller than the virial masses of this subsystem. This result is also of particular interest for estimating the dynamic masses of galaxy clusters. It is noted that an increase in the degree of non-stationarity of the considered models of embedded clusters leads to a decrease in the periods of oscillations of the stellar subsystem.</p>","PeriodicalId":478,"journal":{"name":"Astrophysical Bulletin","volume":"79 1","pages":"71 - 87"},"PeriodicalIF":1.3,"publicationDate":"2024-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140932547","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Velocity Dispersion and H(boldsymbol{alpha})-emission of Ionized Gas in Star-forming Regions","authors":"E. O. Vasiliev,&nbsp;Yu. A. Shchekinov","doi":"10.1134/S1990341323600242","DOIUrl":"10.1134/S1990341323600242","url":null,"abstract":"<p>To understand the nature of gas flows in star-forming regions of nearby galaxies, the relationship between the surface brightness values in the H<span>(alpha)</span> line and the velocity dispersion of ionized gas, known as the ‘‘surface brightness–velocity dispersion’’ diagram, is often used. Based on three-dimensional gas-dynamic calculations, we examined the evolution of synthetic diagrams for supershells formed as a result of multiple supernova explosions in a star cluster located in the galactic disk. Based on the results of a study of changes in the shape and structure of the diagram depending on the gas density, its metallicity, and the disk scale height, it is possible to identify ranges of values in the diagram that are characteristic of young bubbles developing in dense or rarefied gas at large heights above the plane of the disk. We found that the structure of the diagram depends on the age of the supershells and the physical properties of the gas in the disk. For nearby dwarf galaxies, the structure of the observed ‘‘surface brightness–velocity dispersion’’ diagrams can only be explained by describing the dynamics of bubbles formed by multiple SN explosions in small star clusters of different ages.</p>","PeriodicalId":478,"journal":{"name":"Astrophysical Bulletin","volume":"79 1","pages":"60 - 70"},"PeriodicalIF":1.3,"publicationDate":"2024-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140932540","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Progress in Supernovae Studies with the 2.5-m Telescope at the Caucasus Mountain Observatory of SAI MSU","authors":"D. Yu. Tsvetkov,&nbsp;N. N. Pavlyuk,&nbsp;V. A. Echeistov,&nbsp;P. V. Baklanov","doi":"10.1134/S1990341323700232","DOIUrl":"10.1134/S1990341323700232","url":null,"abstract":"<p>We present photometric and spectrocsopic observations of supernovae carried out with the 2.5-m telescope of the Caucasus Mountain Observatory of SAI MSU. The light curves for the objects 2017egm, 2017eaw, 2018cow, 2018aoq, 2018zd, 2019yvr, 2019vxm, 2020tlf, and 2020xtz were constructed and their basic parameters were determined. The observed light curves are compared to the theoretical calculations for SNe II-P 2017eaw and 2018aoq. The spectra of SNe 2019vxm, 2019yvr, 2020tlf, 2020xtz are presented. The profiles of emission lines are studied for SNe IIn 2019vxm and 2020tlf. Spectral modeling was carried out for SNe 2019yvr and 2020xtz. The results of the program of prompt SNe spectral classification for eight objects are reported.</p>","PeriodicalId":478,"journal":{"name":"Astrophysical Bulletin","volume":"78 4","pages":"514 - 534"},"PeriodicalIF":1.3,"publicationDate":"2024-03-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140019320","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Magnetic Fields in Chemically Peculiar and Related Stars. IX. Main Results Obtained in 2022 and an Analysis of Immediate Prospects","authors":"I. I. Romanyuk","doi":"10.1134/S1990341323700244","DOIUrl":"10.1134/S1990341323700244","url":null,"abstract":"<p>We review the stellar magnetism studies published in 2022.\u0000We analyzed a total of 75 papers, which focus mostly on the study of\u0000magnetic fields in chemically peculiar and active\u0000cool stars. In the latter, migration of magnetic spots and change\u0000of their configuration is observed. Projects of spectrographs and\u0000spectropolarimeters for new big telescopes are also presented.</p>","PeriodicalId":478,"journal":{"name":"Astrophysical Bulletin","volume":"78 4","pages":"594 - 605"},"PeriodicalIF":1.3,"publicationDate":"2024-03-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140019430","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Results of Magnetic Field Measurements with the 6-m BTA Telescope. IX. Observations in 2015","authors":"I. I. Romanyuk,&nbsp;A. V. Moiseeva,&nbsp;E. A. Semenko,&nbsp;I. A. Yakunin,&nbsp;D. O. Kudryavtsev","doi":"10.1134/S1990341323700207","DOIUrl":"10.1134/S1990341323700207","url":null,"abstract":"<p>The paper presents magnetic field measurements and physical\u0000parameters for 96 stars. Observations were carried out in 2015\u0000with the 6-m BTA telescope using the Main Stellar Spectrograph\u0000(MSS). By analyzing circularly polarized spectra, the magnetic\u0000fields of the stars HD 653, HD 8855, HD 94603, HD 188101\u0000(KIC 6065699), HD 189160,\u0000HD 195464, and BD+44<span>({}^{circ})</span> 4130 were discovered for the first time.\u0000No systematic measurement errors were detected.</p>","PeriodicalId":478,"journal":{"name":"Astrophysical Bulletin","volume":"78 4","pages":"567 - 587"},"PeriodicalIF":1.3,"publicationDate":"2024-03-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140019460","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}