Kolotsey A., Atroschenco M., Dubrouski S.A., Baluk I.I «Updated light elements of 10 RRab stars in the Antlia, Caelum and Sculptor constellations» Публикации Одесской астрономической обсерватории (Odessa Astronomical Publications, Украина), 30, с. 85-88 (2017)

DOI: https://doi.org/10.18524/1810-4215.2017.30.117671 This paper presents the results of verification of the periods and other characteristics of 10 variable stars. The All Sky Automated Survey (ASAS) data have been used in this verification study. 10 RRab stars in the Antlia, Caelum and Sculptor constellations have been investigated. The study was performed using the software package developed by S.A. Dubrouski and V.P. Goranski.

Lozitsky V.G., Baranovsky E.A., Lozitska N.I., Tarashchuk V.P. «Estimations of local magnetic fields in solar flares: basic methods and some results» Публикации Одесской астрономической обсерватории (Odessa Astronomical Publications, Украина), 30, с. 232-235 (2017)

DOI: https://doi.org/10.18524/1810-4215.2017.30.114690 We consider three methods for estimations of local magnetic fields in solar flares: (1) analysis of bisectors of I±V profiles (Lozitsky, 2015); (2) search for Zeeman-like effects in cores of spectral lines with very low Lande factors, g_eff≈0.01 (Lozitsky, 1993, 1998); (3) semi-empirical modeling using many spectral lines and two-component models (see, e.g., Lozitsky et al., 2000). We illustrate the application of named methods to different observational data and to different spectral lines. Our main conclusions are following: (a) upper limit of local magnetic fields in solar flares is, at least, ∼10⁴G, (b) such extremely strong fields can occur in very small, spatially unresolved scales, (c) lifetime of such fields is, at least, a few minutes.

Mishenina T., Klochkova V., Panchuk V., Basak N., Kovtyukh V., Korotin S., Velichko A. «Three giants – members of the open cluster M 67» Публикации Одесской астрономической обсерватории (Odessa Astronomical Publications, Украина), 30, с. 108-112 (2017)

DOI: https://doi.org/10.18524/1810-4215.2017.30.114355 We determined the atmospheric parameters and chemical composition of the three giants, which are members of the open cluster M 67. The high resolution spectra (R=60 000) were obtained with the echelle spectrograph NES mounted on the 6-metertelescope of the SAO RAS Obtained variations in Na and Zr abundances are within the determination errors. The Li abundance suggest a depletion of Li in the course ofstellar evolution. For studied giants, the iron abundances derived from the neutral and ionized iron lines have not shown any significant discrepancies. The [Ba/Fe] values are close to the solar ones.

Ismailov N.Z., Adigezalzade A.N., Bashirova U.Z. «Circustellar matter activity in AE/BE Herbig star MWC 614» Публикации Одесской астрономической обсерватории (Odessa Astronomical Publications, Украина), 30, с. 78-84 (2017)

DOI: https://doi.org/10.18524/1810-4215.2017.30.117155 The results of spectral observations of the Herbig Ae/Be type star HD 179218 are presented. Two wave-like cycles of variability in the parameters of hydrogen lines H_α and H_β with a characteristic time of ∼40 days are revealed. The first wave of variations is deeper; the branches of decreasing and increasing the spectral parameters of the lines are more clearly expressed. At the time of the first minimum, in the profile of the emission line H_α the appearance and disappearance of additional blue and red emission components are observed. At the same time, narrow absorption components were discovered in the H_β line. Possible mechanisms of the observed variability of the star are discussed.

Usenko I.A., Kniazev A.Yu., Kovtyukh V.V., Belik S.I., Berdnikov L.N. «Spectroscopical study of faint southern Cepheids with Southern African large telescope (SALT). first results» Публикации Одесской астрономической обсерватории (Odessa Astronomical Publications, Украина), 30, с. 143-145 (2017)

DOI: https://doi.org/10.18524/1810-4215.2017.30.117156 First Cepheids observations using echelle-spectrograph HRS fed by Southern African Large Telescope (SALT) were realized during 2016. All spectra have been obtained in the medium resoltion mode (R≈31000–41000) with high S/N ratio near 50–220. All data were processed using package developed by authors based on the standard system of astronomical data reduction MIDAS. Using new echelle data we found the atmosphere parameters and chemical composition for 30 faint Cepheids of southern hemisphere, where for the most of theses stars these results we obtained for the first time. 28 stars are Cepheids after the first-dredge up stage, while ASAS 075842-25336.1 and ASAS 1131714-6605.0 having remarkable Li I 6707.8 A absorption line and anomalous CNO and Na content could be consider as first crossing of the Cepheids instability strip.

Belubekyan M.V., Papyan A.H. «Vibrations of piezoelectric layer of class 6 mm with initial conditions and with rigidly clamped and free edges» Ученые записки Ереванского государственного университета, физико-математических наук, 54, № 3, с. 146-152 (2020)

Рассматривается задача колебаний пьезоэлектрического слоя 6 mm-класса при начальных условиях в виде воздействия внешнего электрического поля или перемещения слоя, когда один его край жестко защемлен, а другой свободен. Задача рассматривается на основе гиперболических уравнений электромагнитного поля. Определены перемещение слоя и внешнее электрическое поле.

Алешкин В.М., Bouttout A., Субботкин А.О., Benferhat M.L., Amara M. «Акустика мечети Кетшава в Алжире» Акустический журнал, 67, № 3, с. 308-318 (2021)

Представлены результаты акустического обследования крупной соборной мечети Кетшава (Ketchaoua), расположенной в г. Алжир (Алжирская Народная Демократическая Республика), а также обзор на ее примере основных проблем акустики молельных залов культовых сооружений, таких как храмы и мечети. Мечеть построена в XVII веке и является одной из основных достопримечательностей столицы Алжира. Измерения в молельном зале мечети проведены согласно международной методике ISO 3382. Приводятся данные по времени реверберации, разборчивости речи и другим критериям акустического качества. Анализ полученных результатов и субъективная оценка акустики мечети показывают, что разборчивость речи в молельном зале недостаточна. Измеренные акустические критерии сопоставляются с оптимальными значениями и результатами обследования некоторых других мечетей. Формулируются возможные пути решения улучшения качества звучания архитектурно-акустическими методами. DOI: 10.31857/S0320791921030011

Usenko I.A., Kniazev A.Yu., Kovtyukh V.V., Belik S.I., Berdnikov L.N. «Spectroscopical study of faint southern Cepheids with Southern African large telescope (SALT). first results» Публикации Одесской астрономической обсерватории (Odessa Astronomical Publications, Украина), 30, с. 143-145 (2017)

DOI: https://doi.org/10.18524/1810-4215.2017.30.117156 First Cepheids observations using echelle-spectrograph HRS fed by Southern African Large Telescope (SALT) were realized during 2016. All spectra have been obtained in the medium resoltion mode (R≈31000–41000) with high S/N ratio near 50–220. All data were processed using package developed by authors based on the standard system of astronomical data reduction MIDAS. Using new echelle data we found the atmosphere parameters and chemical composition for 30 faint Cepheids of southern hemisphere, where for the most of theses stars these results we obtained for the first time. 28 stars are Cepheids after the first-dredge up stage, while ASAS 075842-25336.1 and ASAS 1131714-6605.0 having remarkable Li I 6707.8 A absorption line and anomalous CNO and Na content could be consider as first crossing of the Cepheids instability strip.

Maigurova N.V., Pomazan A.V., Bodryagin D.V., Bondarchuk L.E. «Accuracy of Mykolaiv asteroid observations with different reference catalogues» Публикации Одесской астрономической обсерватории (Odessa Astronomical Publications, Украина), 30, с. 182-185 (2017)

DOI: https://doi.org/10.18524/1810-4215.2017.30.114488 The results of astrometric reductions of main belt asteroid observations with usage of 3 different reference catalogues are presented. The high precision catalogs CMC15, UCAC4 and GAIA DR1 were used as reference catalogues for calculation asteroid equatorial coordinates. The asteroid observations were carried out at KT-50 telescope of the RI “MAO” Mobitel complex during 2016. The array contains 1666.positions of 68 asteroids mainly in range of (11–15) magnitudes. The differences (O–C) were calculated by comparing the obtained topocentric positions with the HORIZONS ephemeredes of the JPL laboratory. The mean square errors of the (O–C) values were used for comparison of the different reductions model. The influence of the choice of the reference catalog on the random and systematic asteroid position errors is shown.

Bolotin Yu.L., Cherkaskiy V.A., Yanovsky V.V. «Limit values as an universal method of description of physical reality» Публикации Одесской астрономической обсерватории (Odessa Astronomical Publications, Украина), 30, с. 6-12 (2017)

There are two main forms of cognition of Nature: empiric knowledge obtained from the experience, and theory as system of ideas and principles. Each of the two forms uses its own methods. While empirics or phenomenology is based on experiments, theory mostly deals with axiomatic approach. Every axiomatics starts from the principal question: what statements should be chosen as axioms? The present work uses the existence of limit values as the initial axiom. It is well known that the statement about the existence of minimum quantum of action ħ is sufficient to build all the Quantum Mechanics, likewise maxi-mum velocity value c – for the Special Relativity. Similar approach can be realized in General Relativity as well, which can be built on the postulated existence of limit (maximum) power η≪em>c/4G. It seems natural in context of this axiomatics to transit from the traditional Planck’s units to the modified ones, i.e. from the set (ħ, c, G) to (ħ, c, ħ), with the latter containing exclusively limit values. The approach considered in the present paper opens new exciting possibilities for interpretation of the known results and obtaining the new ones.

Bolotin Yu.L., Zazunov L.G., Konchatnyi M.I., Lemets O.A. «The ABC of cosmography» Публикации Одесской астрономической обсерватории (Odessa Astronomical Publications, Украина), 30, с. 13-15 (2017)

DOI: https://doi.org/10.18524/1810-4215.2017.30.114129

Maigurova N.V., Pomazan A.V., Bodryagin D.V., Bondarchuk L.E. «Accuracy of Mykolaiv asteroid observations with different reference catalogues» Публикации Одесской астрономической обсерватории (Odessa Astronomical Publications, Украина), 30, с. 182-185 (2017)

DOI: https://doi.org/10.18524/1810-4215.2017.30.114488 The results of astrometric reductions of main belt asteroid observations with usage of 3 different reference catalogues are presented. The high precision catalogs CMC15, UCAC4 and GAIA DR1 were used as reference catalogues for calculation asteroid equatorial coordinates. The asteroid observations were carried out at KT-50 telescope of the RI “MAO” Mobitel complex during 2016. The array contains 1666.positions of 68 asteroids mainly in range of (11–15) magnitudes. The differences (O–C) were calculated by comparing the obtained topocentric positions with the HORIZONS ephemeredes of the JPL laboratory. The mean square errors of the (O–C) values were used for comparison of the different reductions model. The influence of the choice of the reference catalog on the random and systematic asteroid position errors is shown.

Bouaziz-Kellil F. «Three-Dimensional Version of Hill's Problem with Variable Mass» Письма в Астрономический журнал: Астрономия и космическая физика, 47, № 4, с. 300-300 (2021)

DOI: 10.31857/S0320010821040045

Алешкин В.М., Bouttout A., Субботкин А.О., Benferhat M.L., Amara M. «Акустика мечети Кетшава в Алжире» Акустический журнал, 67, № 3, с. 308-318 (2021)

Представлены результаты акустического обследования крупной соборной мечети Кетшава (Ketchaoua), расположенной в г. Алжир (Алжирская Народная Демократическая Республика), а также обзор на ее примере основных проблем акустики молельных залов культовых сооружений, таких как храмы и мечети. Мечеть построена в XVII веке и является одной из основных достопримечательностей столицы Алжира. Измерения в молельном зале мечети проведены согласно международной методике ISO 3382. Приводятся данные по времени реверберации, разборчивости речи и другим критериям акустического качества. Анализ полученных результатов и субъективная оценка акустики мечети показывают, что разборчивость речи в молельном зале недостаточна. Измеренные акустические критерии сопоставляются с оптимальными значениями и результатами обследования некоторых других мечетей. Формулируются возможные пути решения улучшения качества звучания архитектурно-акустическими методами. DOI: 10.31857/S0320791921030011

Savanevych V.E., Briukhovetskyi O.B., Khlamov S.V., Pohorelov A.V., Vlasenko V.P., Dubovsky P.A., Kudzej I., Parimucha Š. «COLITECVS – new tool for automated reduction of photometric observations» Публикации Одесской астрономической обсерватории (Odessa Astronomical Publications, Украина), 30, с. 194-197 (2017)

DOI: https://doi.org/10.18524/1810-4215.2017.30.114495 The capabilities of telescopes allow us to make the plotting of light curves a routine task. This one shifts the main attention of astronomer from the plotting to research. To achieve this goal, we developed a new tool for automated reduction of photometric observations, which includes the computational method for the brightness assessment of the investigated and comparison stars; brightness equalization of astronomical images using inverse median filter; light curve plotting and its processing using different tools.

Kotvytskiy A.T., Bronza S.D., Shablenko V.Yu. «Correlation of the number of images of an n-point gravitational lens and the number of solutions of its system» Публикации Одесской астрономической обсерватории (Odessa Astronomical Publications, Украина), 30, с. 35-37 (2017)

DOI: https://doi.org/10.18524/1810-4215.2017.30.114229. In this paper, we study the correlation between the number of solutions of a system of lens equations and the number of source images that a gravitational lens has. We defined the concept of an image in a gravitational lens. To find the set of solutions of a system of lens equations, we applied methods of algebraic geometry.

Oknyansky V.L., Gaskell C.M., Huseynov N.A., Mikailov Kh.M., Lipunov V.M., Malanchev N.I., Tsygankov S.S., Gorbovskov E.S., Tatarnikov A.M., Metlov V.G., Shatsky K.L., Brotherton M.B., Kasper D., Du P., Chen X., Burlak M.A., Buckley D.A.H., Rebolo R., Serra-Ricart M., Podesta R., Levato H. «Ulti-wavelength monitoring of the changing-look AGN NGC 2617 during state changes» Публикации Одесской астрономической обсерватории (Odessa Astronomical Publications, Украина), 30, с. 117-120 (2017)

DOI: https://doi.org/10.18524/1810-4215.2017.30.114366 Optical and near-infrared photometry, optical spectroscopy, and soft X-ray and UV monitoring of the changing-look active galactic nucleus NGC 2617 show that it continues to have the appearance of a type-1 Seyfert galaxy. An optical light curve for 2010–2017 indicates that the change of type probably occurred between 2010 October and 2012 February and was not related to the brightening in 2013. In 2016 and 2017 NGC 2617 brightened again to a level of activity close to that in 2013 April. However, in 2017 from the end of the March to end of July 2017 it was in very low level and starting to change back to a Seyfert 1.8. We find variations in all passbands and in both the intensities and profiles of the broad Balmer lines. A new displaced emission peak has appeared in H_β. X-ray variations are well correlated with UV–optical variability and possibly lead by ∼2–3^d. The K band lags the J band by about 21.5±2.5^d and lags the combined B+J bands by ∼25^d. J lags B by about 3 d. This could be because J-band variability arises predominantly from the outer part of the accretion disc, while K-band variability is dominated by thermal re-emission by dust. We propose that spectral-type changes are a result of increasing central luminosity causing sublimation of the innermost dust in the hollow bi-conical outflow. We briefly discuss various other possible reasons that might explain the dramatic changes in NGC 2617.

Oknyansky V.L., Gaskell C.M., Huseynov N.A., Mikailov Kh.M., Lipunov V.M., Malanchev N.I., Tsygankov S.S., Gorbovskov E.S., Tatarnikov A.M., Metlov V.G., Shatsky K.L., Brotherton M.B., Kasper D., Du P., Chen X., Burlak M.A., Buckley D.A.H., Rebolo R., Serra-Ricart M., Podesta R., Levato H. «Ulti-wavelength monitoring of the changing-look AGN NGC 2617 during state changes» Публикации Одесской астрономической обсерватории (Odessa Astronomical Publications, Украина), 30, с. 117-120 (2017)

DOI: https://doi.org/10.18524/1810-4215.2017.30.114366 Optical and near-infrared photometry, optical spectroscopy, and soft X-ray and UV monitoring of the changing-look active galactic nucleus NGC 2617 show that it continues to have the appearance of a type-1 Seyfert galaxy. An optical light curve for 2010–2017 indicates that the change of type probably occurred between 2010 October and 2012 February and was not related to the brightening in 2013. In 2016 and 2017 NGC 2617 brightened again to a level of activity close to that in 2013 April. However, in 2017 from the end of the March to end of July 2017 it was in very low level and starting to change back to a Seyfert 1.8. We find variations in all passbands and in both the intensities and profiles of the broad Balmer lines. A new displaced emission peak has appeared in H_β. X-ray variations are well correlated with UV–optical variability and possibly lead by ∼2–3^d. The K band lags the J band by about 21.5±2.5^d and lags the combined B+J bands by ∼25^d. J lags B by about 3 d. This could be because J-band variability arises predominantly from the outer part of the accretion disc, while K-band variability is dominated by thermal re-emission by dust. We propose that spectral-type changes are a result of increasing central luminosity causing sublimation of the innermost dust in the hollow bi-conical outflow. We briefly discuss various other possible reasons that might explain the dramatic changes in NGC 2617.

Oknyansky V.L., Gaskell C.M., Huseynov N.A., Mikailov Kh.M., Lipunov V.M., Malanchev N.I., Tsygankov S.S., Gorbovskov E.S., Tatarnikov A.M., Metlov V.G., Shatsky K.L., Brotherton M.B., Kasper D., Du P., Chen X., Burlak M.A., Buckley D.A.H., Rebolo R., Serra-Ricart M., Podesta R., Levato H. «Ulti-wavelength monitoring of the changing-look AGN NGC 2617 during state changes» Публикации Одесской астрономической обсерватории (Odessa Astronomical Publications, Украина), 30, с. 117-120 (2017)

DOI: https://doi.org/10.18524/1810-4215.2017.30.114366 Optical and near-infrared photometry, optical spectroscopy, and soft X-ray and UV monitoring of the changing-look active galactic nucleus NGC 2617 show that it continues to have the appearance of a type-1 Seyfert galaxy. An optical light curve for 2010–2017 indicates that the change of type probably occurred between 2010 October and 2012 February and was not related to the brightening in 2013. In 2016 and 2017 NGC 2617 brightened again to a level of activity close to that in 2013 April. However, in 2017 from the end of the March to end of July 2017 it was in very low level and starting to change back to a Seyfert 1.8. We find variations in all passbands and in both the intensities and profiles of the broad Balmer lines. A new displaced emission peak has appeared in H_β. X-ray variations are well correlated with UV–optical variability and possibly lead by ∼2–3^d. The K band lags the J band by about 21.5±2.5^d and lags the combined B+J bands by ∼25^d. J lags B by about 3 d. This could be because J-band variability arises predominantly from the outer part of the accretion disc, while K-band variability is dominated by thermal re-emission by dust. We propose that spectral-type changes are a result of increasing central luminosity causing sublimation of the innermost dust in the hollow bi-conical outflow. We briefly discuss various other possible reasons that might explain the dramatic changes in NGC 2617.

Plachinda S.I., Butkovskaya V.V. «Stellar activity cycles: why do we need in the long-term measurements of the magnetic field?» Публикации Одесской астрономической обсерватории (Odessa Astronomical Publications, Украина), 30, с. 124-125 (2017)

DOI: https://doi.org/10.18524/1810-4215.2017.30.114374 Solution of the two important problems requires a study of long-term behavior of the magnetic field on stars with nondegenerate matter: firstly, to define the role of the magnetic field on different evolutionary stages of stars; secondly, to know the influence of the star’s activity on space weather in the habitable zone. This brief review summarizes the first results of the long-term magnetic field measurements on selected stars.