Репозитарій ОНУ імені І.І.Мечникова

Перегляд за Автор "Andrievsky, Serhii M."

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A new 800 mm automatic telescope
(Astroprint, 2013) Andrievsky, Serhii M.; Molotov, I. E.; Fashchevsky, N. N.; Podlesnyak, S. V.; Zhukov, V. V.; Kouprianov, V. V.; Kashuba, S. G.; Kashuba, V. I.; Mel’nichenko, V. F.; Gorbanev, Juri M.; Андрієвський, Сергій Михайлович; Андриевский, Сергей Михайлович
ABSTRACT. A new automatic telescope, a 800-millimeter main mirror catadioptric anastigmatic aplanat, was constructed by specialists of Odessa National University Astronomical observatory (Ukraine) in cooperation with their colleagues from the ISON project (Russia), and was recently put into operation. The telescope is mounted at Mayaki station in suburb of Odessa. It is equipped with a focal corrector and a professional CCD camera. The telescope is used now for observations of geostationary objects, asteroids, and comets. In addition, this telescope can be used for the high precision photometric observations of faint objects up to 20m.
About chemical composition of supergiant PMMR145 in Small Magellanic cloud. Osmium.
(Astroprint, 2012) Gopka, Vera F.; Shavrina, Angelina V.; Vasilyeva, S. V.; Andrievsky, Serhii M.; Андрієвський, Сергій Михайлович; Андриевский, Сергей Михайлович
ABSTRACT. The abundance analysis of six Ksupergiants of the Small Magellanic (Hill 1997) showed that the heavier elements (La, Ce, Nd, Eu) have the excess relative to iron [El/Fe]=+0.4 dex, on average, for the sample of five stars (PMMR23, PMMR27, PMMR48, PMMR102, PMMR145). We made the identification of spectral lines in the spectrum of PMMR145 based on the comparison of synthetic and observed spectra. The absorption lines of elements heavier than lanthanides including osmium were identified and abundance of osmium was found ([Os/Fe]=0.59 dex).
An enigma of the Przybylski star
(Одеський національний університет імені І. І. Мечникова, 2022) Andrievsky, Serhii M.; Андрієвський, Сергій Михайлович
A new scenario to explain the Przybylski star phenomenon is proposed. It is based on the supposition that this star is a component of a binary system with a neutron star (similar to the hypothesis proposed earlier by Gopka, Ul’yanov & Andrievskii). The main difference with previous scenario is as follows. The orbits of the stars of this system lie in the plane of the sky (or very close to this plane). Thus, we see this star (and its companion) nearly polar-on, and therefore we cannot detect the orbital motion (spectral line based) from the Przybylski’s star spectrum. In relation to the Przybylski star, the neutron star is a γ-ray pulsar for it. A neutron star is a source of relativistic particles and radiation emitted from the certain parts of its surface. The topology of this radiation strongly depends on the the magnetic field configuration of the neutron star. Existing models suppose that 1) high-energy electron-positron pairs and hard radiation are produced in the (magnetic) polar zones. Accelerated charge particles that move along magnetic lines emit electromagnetic quanta. In this model the radio-emission is genetically linked with the emission of the γ-quanta. 2) Another model of the outer gap is based on the assumption that there is a vacuum gap in the outer magnetosphere of the neutron star, which arises due to the constant escape of charged particles through the light cylinder along the open magnetic field lines. The direction of such escape may be roughly orthogonal to the rotation axis. If the rotation axes of the Przybylski star and the neutron star are close in direction (or even aligned), charged particles and hard radiation ejected in the approximately orthogonal direction at a large solid angle can enter the Przybylski’s star atmosphere, causing there different physical processes. As a possible source of the free neutrons could be the nuclear reactions between high-energy γ-quanta and nuclei of some atoms in the Przybylski’s star atmosphere gas. As a result, photoneutrons can be generated. Large enough neutron flux can be produced in the reactions with quite abundant element of the atmosphere gas (for example, helium). The photoneutrons produced in these reactions are rapidly thermalized and, as resonant neutrons, react with seed nuclei in the s-process. It should be also noted that together with s-process elements, the deuterium nuclei could be formed as a result of the interactions of the free resonant neutrons with the hydrogen atoms, but this issue has not yet been worked out.
Are the s-Cepheids crossing the instability strip for the first time?
(Astroprint, 2012) Andrievsky, Serhii M.; Harbuzov H. O.; Doikov, D. N.; Андрієвський, Сергій Михайлович; Андриевский, Сергей Михайлович
Using the literature data on secular period changes reported for the small-amplitude Cepheids (s-Cepheids) it is shown that these stars are not crossing the instability strip for the first time. After correction of the observed pulsational chracteristics of s-Cepheids, in the diagram ”log(dP/P)100 - log P” they become indistinguishable from usual classic Cepheids, which are supposed to have already crossed the instability strip more than (or at least) once.
Astronegative archive of Odessa observatory. Large surveys with small telescopes
(2019) Kashuba, S. V.; Bazyey, N. V.; Kashuba, V. I.; Andrievsky, Serhii M.; Андрієвський, Сергій Михайлович; Андриевский, Сергей Михайлович
Currently Observatory of I. I. Mechnikov Odessa National University owns collections of astronegatives obtained with its own instruments (about 100000 glass plates), as well as those obtained with instruments from other observatories (about 10000 plates). According to Bulgarian web-page WFPDB (wfpdb.org) Odessa collection of astroplates is second in Europe (after Sonneberg collection) and third in the world (after Harvard and Sonneberg). In this poster we describe the current condition of our collection and consider our plans for how to maintain this important astronomical heritage. We are also discussing our first steps in digitizing part of a collection in accordance with the decision of the world virtual observatory and WFPDB standards.
Coopération Franco-Ukrainienne dans dans l'étude de l'évolution chimique de Notre Galaxie
(2019) Andrievsky, Serhii M.; Андрієвський, Сергій Михайлович; Андриевский, Сергей Михайлович
Notre Galaxie comprend différentes sous-structures : disques minces et épais, renflement, halo, etc. Ces sous-structures contiennent des étoiles de types différents, en particulier de niveau de métallicité différente. Une étude de la composition chimique de ces étoiles fournit une information cruciale sur l'évolution chimique de notre système stellaire dans son ensemble. Jusqu'à présent, nous n'avions pas de solution définitive au problème de la formation de la Voie Lactée : s'agit-il d'un processus hiérarchique allant de la grande structure aux plus petites sous-structures, ou bien notre galaxie s'est-elle formée à la suite de processus de fusion impliquant des systèmes stellaires plus petits, tels que des galaxies naines et des amas globulaires ? L'étude des propriétés chimiques des étoiles de différentes sous-structures de la Voie Lactée peut éclairer cette énigme astrophysique.
Diffuse interstellar band 6202 ˚a as an indicator of organic matter in cosmos: cepheid spectra
(Одеський національний університет імені І. І. Мечникова, 2019) Andrievsky, Serhii M.; Shereta, E. P.; Khrapaty, S. V.; S. A. Korotin; Kovtyukh, Valery V.; Kashuba, V. I.; Андрієвський, Сергій Михайлович; Андриевский, Сергей Михайлович; Ковтюх, Валерій В.
We have described the method of investigation of the diffuse interstellar band (DIB) at 6202 ˚A. This DIB is seen in the spectra of cepheid stars, and it is blended with two stellar lines of Ce II (6201.773 ˚A) and Ni I (6204.6 ˚A). After removal of the blending lines of ionized cerium and neutral nickel, we can determine the equivalent widths (EW) of the DIB. This procedure can be applied for the sample of cepheids (with well known distances), which enables one to construct the map of the organic matter distribution in the Galactic disc and use these values to investigate the E(B–V)–DIB EW relation. The relation found from Cepheids matches that found in B stars. This relation can help to find the reddening for newly discovered Cepheids without extensive photometric data, and thus determine their distances. The relation between E(B–V) and the DIB EW does not yield precise reddening values. It is not a substitute for better photometric or spectroscopic methods. At best, it is indicative, but it provides some information that may not be otherwise available.
GIANO Y-band spectroscopy of dwarf stars: Phosphorus, sulphur, and strontium abundances
(2016) Caffau, E.; Andrievsky, Serhii M.; Korotin, Sergei A.; Origlia, L.; Oliva, E.; Sanna, N.; Ludwig, H.-G.; Bonifacio, P.; Андрієвський, Сергій Михайлович; Андриевский, Сергей Михайлович
Context. In recent years a number of poorly studied chemical elements, such as phosphorus, sulphur, and strontium, have received special attention as important tracers of the Galactic chemical evolution. Aims. By exploiting the capabilities of the infrared echelle spectrograph GIANO mounted at the Telescopio Nazionale Galileo, we acquired high resolution spectra of four Galactic dwarf stars spanning the metallicity range between about one-third and twice the solar value. We performed a detailed feasibility study about the effectiveness of the P, S, and Sr line diagnostics in the Y band between 1.03 and 1.10 μm. Methods. Accurate chemical abundances have been derived using one-dimensional model atmospheres computed in local thermodynamic equilibrium (LTE).We computed the line formation assuming LTE for P, while we performed non-LTE analysis to derive S and Sr abundances. Results. We were able to derive phosphorus abundance for three stars and an upper limit for one star, while we obtained the abundance of sulphur and strontium for all of the stars. We find [P/Fe] and [S/Fe] abundance ratios consistent with solar-scaled or slightly depleted values, while the [Sr/Fe] abundance ratios are more scattered (by ±0.2 dex) around the solar-scaled value. This is fully consistent with previous studies using both optical and infrared spectroscopy. Conclusions. We verified that high-resolution, Y-band spectroscopy as provided by GIANO is a powerful tool to study the chemical evolution of P, S, and Sr in dwarf stars.
Investigation of diffuse interstellar bands of organic molecules in the spectra of cepheid stars
(Одеський національний університет імені І. І. Мечникова, 2015) Kashuba, S. V.; Andrievsky, Serhii M.; Chekhonadskikh, F. A.; Korotin, S. A.; Kovtyukh, Valery V.; Luck, R. E.; Андрієвський, Сергій Михайлович; Андриевский, Сергей Михайлович
We describe an effective method of investigation of the Diffuse Interstellar Bands (DIBs) in the spectra of Cepheid stars. DIBs are believed to originate from the absorption of such carriers as polycyclic aromatic hydrocarbons in the interstellar gaseous clouds located between an observer and the stars whose spectra were recorded. We performed a detailed consideration of the DIB at 6613 A in our sample of spectra for more than 250 stars. The quantitative characteristics of the DIB absorption features will be studied in connection with the interstellar absorption data, and after that, they will be used in the mapping of the Galactic disc.
Ionisation loss and shock excitation of 44/20 Са I and 44/20 Са II atoms in cold remnants of type II supernovae
(Одеський національний університет імені І. І. Мечникова, 2017) Doikov, D. N.; Andrievsky, Serhii M.; Андрієвський, Сергій Михайлович; Андриевский, Сергей Михайлович
The light emission (“glow”) of cold dusty plasma of the remnant of SN1987A was confirmed by the Hubble Space Telescope observations on 7th January, 1995. In particular, Ca I and Ca II lines were recorded and identified in the spectrum of the supernova’s envelope. The period of complete hydrogen recombination in the remnant is 800 days. Thus, it is only radioactive decay that could be a primary source of the plasma light emission at the moment of observation. This paper describes the conditions of shock excitation and recombination of 44/20 Ca resulted from the decay of radioactive 44/20 Ti travelling in the remnant’s cold dust. The overionisation in the remnant resulted from the motion of the 44/20 Ca recoil nucleus, as well as its impact on the spectrum formation, was studied. It has been shown that the calcium lines are formed by the 44/20 Ca II ion in the inner layers of the remnant. We have reached the conclusion that the Ca I/Ca II lines strength ratio corresponds to the isotopic abundance ratio [44/20 Ca] /[44/20 Ca ] in type II supernova remnants.
Isolated clusters of PF catalogue
(Astroprint, 2012) Panko, Olena O.; Andrievsky, Serhii M.; Андрієвський, Сергій Михайлович; Андриевский, Сергей Михайлович; Панько, Елена Алексеевна; Панько, Олена Олексіївна
The properties of isolated galaxy clusters are discussed. The clusters were found among 1746 PF clusters inclusive 50 and more galaxies in structure field. For 19 clusters with distances to the nearest neighbour larger than 68.5 h-1 Mpc we assigned the morphological types of these clusters according to Abell and Bauts & Morgan. The existence of preferential planes and angular momenta of isolated clusters was assumed. We connect evolution of isolated clusters with common large-scale characteristics.
Monitoring of space objects using Odessa Observatory network of telescope
(2019) Andrievsky, Serhii M.; Bazyey, N. V.; Zhukov, V. V.; Koshkin, Nikolay I.; Kashuba, V. I.; Kashuba, S. V.; Gorbanev, Yuriy M.; Sukhov, P. P.; Podlesnyak, S. V.; Udovichenko, S. N.; Keir, L. E.; Андрієвський, Сергій Михайлович; Андриевский, Сергей Михайлович; Кошкін, Микола Іванович; Кошкин, Николай Иванович; Горбаньов, Юрій Михайлович; Горбанёв, Юрий Михайлович
In this paper we are presenting optical telescopes of Astronomical Observatory of I. I. Mechnikov Odessa National University. We are describing technical characteristics and scientific program for each telescope. Here we also present a description of the tools with which the unique collections of astroplates were obtained under the program “The Sky Service”. Odessa Observatory (46°.28 N, 30°.45 E, altitude 64 m, observation code 086) it has several observational stations. Among them: Mayaki (46.39° N, 30°.27 E, altitude 25 m, observation code 583) and Kryzhanovka (46°.37 N, 30°.48 E, altitude 40 m, observation code A85). Both stations have a good geographical location, as well as good astroclimate (up to 200 clear nights or part of the night). Telescopes are equipped with modern CCDs and photometric light detectors. Odessa Observatory has its own mechanical and optical workshops that are used for construction the new telescopes and manufacture and repair other astronomical equipment.
Photometric and spectroscopic analysis of Comet 29P/Schwassmann-Wachmann 1 activity
(2016-02) Ivanova, Oleksandra V.; Luk'yanyk, Igor V.; Kiselev, Nikolay N.; Afanasiev, Viktor L.; Picazzio, Enos; Cavichia, Oscar; Almeida, Amaury A. de; Andrievsky, Serhii M.; Андрієвський, Сергій Михайлович; Андриевский, Сергей Михайлович
We carried out photometric and spectroscopic observations of comet 29P/Schwassmann-Wachmann 1 at the 6-m BTA telescope (SAO RAS, Russia) and the 1.6-m telescope of the National Laboratory for Astrophysics (LNA, Brazil) on February 20, 2012, and on May 31, 2011, respectively. The spectra revealed the presence of CO+ and N2+ emissions in the cometary coma at a distance of 5.25 AU from the Sun. The ratio [N2+]/[CO+] within the projected slit is 0.013. The images obtained through BVR filters showed a bright, dust coma, indicating a high level of activity. We estimated a colour index and a colour excess for the comet. The parameter Afρ, which is used as an indicator of a cometary activity, was measured to be 2584±50 cm in the reference optical aperture of ρ=104 km. The dust production constituted 33 kg/s and 9.3·103 kg/s, it was obtained using different methods. We also investigated the morphology of the comet using image enhancement techniques and found two jets in the coma.
Some evolutionary aspects of the binary stellar systems containing neutron star
(Astroprint, 2012) Ulyanov, Oleg O.; Andrievsky, Serhii M.; Gopka, Vera F.; Shavrina, Angelina V.; Андрієвський, Сергій Михайлович; Андриевский, Сергей Михайлович
The obvious lack of the binary stellar systems that contain neutron stars (NS) is observed at present. Partly it is caused by the fact that it is very di cult to detect neutron star in a binary system if this relativistic component does not manifest itself as a radio pulsar. Among 1879 pulsars that are listed in the ATNF pulsar catalogue, only 141 pulsars are known to be the companions in binary systems. Only 81 objects having median mass estimation of more than 0.2 M⊙ constitute the binary systems with pulsars. Nevertheless, such systems should be much more numerous and their investigation is of the great interest because thier structure and evolution can certainly help in our understanding of many unique properties that are seen in some stars.
Some statistical picture of magnetic CP stars evolution
(Astroprint, 2010-07) Gopka, Vera F.; Ulyanov, O. M.; Andrievsky, Serhii M.; Shavrina, Angelina V.; Yushchenko, V. A.; Андрієвський, Сергій Михайлович; Андриевский, Сергей Михайлович
We discuss some statistical results on the evolution of magnetic CP stars in the framework of the supposition about their binary nature.
Spherical primary mirror in telescopes with complex (multi-element) optical designs
(Одеський національний університет імені І. І. Мечникова, 2021) Podlesnyak, S. V.; Fashchevsky, N. N.; Bondarenko, Yu. N.; Andrievsky, Serhii M.; Андрієвський, Сергій Михайлович; Андриевский, Сергей Михайлович
An optical design for telescope with spherical primary mirror, planoidal surface and two-lens corrector is discussed. The spherical mirror has an aperture ratio 1/2.69. After reflection from the spherical mirror, the wave front falls on a planoidal surface and “forms” the reflected wave front from a virtual mirror with e2 = 1.576. After passing the two-lens corrector, the light is collected in the focal plane. A dot diagram in the focal plane shows that all three-order aberrations are successfully corrected. The effective field of view is 2 degrees. The aperture ratio is 1/2.28.
Systematic investigation of chemical abundances derived using IR spectra obtained with GIANO
(2019) Caffau, E.; Bonifacio, P.; Oliva, E.; Korotin, S.; Capitanio, L.; Andrievsky, Serhii M.; Collet, R.; Sbordone, L.; Duffau, S.; Sanna, N.; Tozzi, A.; Origlia, L.; Ryde, N.; Ludwig, H.-G.; Андрієвський, Сергій Михайлович; Андриевский, Сергей Михайлович
ontext. Detailed chemical abundances of Galactic stars are needed in order to improve our knowledge of the formation and evolution of our galaxy, the Milky Way. Aims. We took advantage of the GIANO archive spectra to select a sample of Galactic disc stars in order to derive their chemical inventory and to compare the abundances we derived from these infrared spectra to the chemical pattern derived from optical spectra. Methods. We analysed high-quality spectra of 40 stars observed with GIANO. We derived the stellar parameters from the photometry and the Gaia data-release 2 (DR2) parallax; the chemical abundances were derived with the code MyGIsFOS. For a subsample of stars we compared the chemical pattern derived from the GIANO spectra with the abundances derived from optical spectra. We derived P abundances for all 40 stars, increasing the number of Galactic stars for which phosphorus abundance is known. Results. We could derive abundances of 14 elements, 8 of which are also derived from optical spectra. The comparison of the abun-dances derived from infrared and optical spectra is very good. The chemical pattern of these stars is the one expected for Galactic disc stars and is in agreement with the results from the literature. Conclusions. GIANO is providing the astronomical community with an extremely useful instrument, able to produce spectra with high resolution and a wide wavelength range in the infrared.
The abundances of heavy elements in red supergiants of Magellanic Clouds
(Astroprint, 2013) Gopka, Vera F.; Yushchenko, A. V.; Kovtyukh, Valery V.; Shavrina, Angelina V.; Yushchenko, V. A.; Vasilyeva, S. V.; Pavlenko, Y.; Andrievsky, Serhii M.; Андрієвський, Сергій Михайлович; Андриевский, Сергей Михайлович
ABSTRACT. The spectra of Magellanic Clouds (MC) supergiants PMMR 23, PMMR 144 and RM 1- 667 with resolving power R=30,000 and signal to noise ratio near 100 obtained at 3.6 meter telescope in Chile were analysed. We present a report on the detailed investigation of MC supergiants, with spesial attention to the thorium abundance in these stars. The abundance patterns of three supergiants show that r-process elements are clearly detected in the atmospheres of investigated stars, but the abundances of s-processes elements can vary from star to star.
The CEMP star SDSSJ0222–0313: the first evidence of proton ingestion in very low-metallicity AGB stars?
(2019) Caffau, E.; Monaco, L.; Bonifacio, P.; Korotin, S.; Andrievsky, Serhii M.; Cristallo, S.; Spite, M.; Spite, F.; Sbordone, L.; François, P.; Cescutti, G.; Salvadori, S.; Андрієвський, Сергій Михайлович; Андриевский, Сергей Михайлович
Context. Carbon-enhanced metal-poor (CEMP) stars are common objects in the metal-poor regime. The lower the metallicity we look at, the larger the fraction of CEMP stars with respect to metal-poor stars with no enhancement in carbon. The chemical pattern of CEMP stars is diversified, strongly suggesting a different origin of the C enhancement in the different types of CEMP stars. Aims. We selected a CEMP star, SDSS J0222–0313, with a known high carbon abundance and, from a low-resolution analysis, a strong enhancement in neutron-capture elements of the first peak (Sr and Y) and of the second peak (Ba). The peculiarity of this object is a greater overabundance (with respect to iron) of the first s-process peak than the second s-process peak. Methods. We analysed a high-resolution spectrum obtained with the Mike spectrograph at the Clay Magellan 6.5m telescope in order to derive the detailed chemical composition of this star. Results. We confirmed the chemical pattern we expected; we derived abundances for a total of 18 elements and significant upper limits. Conclusions. We conclude that this star is a carbon-enhanced metal-poor star enriched in elements produced by s-process (CEMP-s), whose enhancement in heavy elements is due to mass transfer from the more evolved companion in its asymptotic giant branch (AGB) phase. The abundances imply that the evolved companion had a low main sequence mass and it suggests that it experienced a proton ingestion episode at the beginning of its AGB phase.
The Gaia RVS benchmark stars I. Chemical inventory of the first sample of evolved stars and its Rb NLTE investigation
(2021) Caffau, E.; Bonifacio, P.; Korotin, S. A.; François, P.; Lallement, R; Matas Pinto, A. M.; Di Matteo, P.; Steffen, M.; Mucciarelli, A.; Katz, D.; Haywood, M.; Chemin, L.; Sartoretti, P.; Sbordone, L.; Andrievsky, Serhii M.; Андрієвський, Сергій Михайлович; Андриевский, Сергей Михайлович; Kovtyukh, V. V.; Spite, M.; Spite, F.; Panuzzo, P.; Royer, F.; Thévenin, F.; Ludwig, H.-G.; Marchal, O.; Plum, G.
Context. The Radial Velocity Spectrometer (RVS) on board the Gaia satellite is not provided with a wavelength calibration lamp. It uses its observations of stars with known radial velocity to derive the dispersion relation. To derive an accurate radial velocity calibration, a precise knowledge of the line spread function (LSF) of the RVS is necessary. Good-quality ground-based observations in the wavelength range of the RVS are highly desired to determine the LSF. Aims. Several radial velocity standard stars are available to the Gaia community. The highest possible number of calibrators will surely allow us to improve the accuracy of the radial velocity. Because the LSF may vary across the focal plane of the RVS, a large number of high-quality spectra for the LSF calibration may allow us to better sample the properties of the focal plane. Methods. We selected a sample of stars to be observed with UVES at the Very Large Telescope, in a setting including the wavelength range of RVS, that are bright enough to allow obtaining high-quality spectra in a short time. We also selected stars that lack chemical investigation in order to increase the sample of bright, close by stars with a complete chemical inventory. Results. We here present the chemical analysis of the first sample of 80 evolved stars. The quality of the spectra is very good, therefore we were able to derive abundances for 20 elements. The metallicity range spanned by the sample is about 1 dex, from slightly metalpoor to solar metallicity.We derived the Rb abundance for all stars and investigated departures from local thermodynamical equilibrium (NLTE) in the formation of its lines. Conclusions. The sample of spectra is of good quality, which is useful for a Gaia radial velocity calibration. The Rb NLTE effects in this stellar parameters range are small but sometimes non-negligible, especially for spectra of this good quality.

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