arXiv subjects

A. V. Tutukov

Publications and source records attributed to A. V. Tutukov.

At least 19 recordsLinked to original sources

arXiv2026

Stellar Wind of Components of Detached Binary Systems

The paper is devoted to the consideration of the role of the donor stellar wind in the matter exchange between the components of detached binary systems. A classification of close binary systems with interacting components is proposed. A list of potential donors and accretors of such systems, including X-ray binary and symbiotic stars, is given. Analytical tasks have been completed to evaluate the conditions and efficiency of interaction through the stellar wind, a criterion was found for maintaining the self-induced stellar wind of X-ray binaries, and a condition for the formation of an accretion disk during accretion of stellar wind matter by a compact accretor. Three-dimensional gas dynamic models of component interaction are constructed for the five initial velocities of the stellar wind using the example of Sco X-1 type systems. The simulation results are illustrated by pictures of streamlines, temperature distribution, and wind gas densities in the orbital and frontal planes. Model focusing of the donor wind flow by the accretor is confirmed by the observed phase X-ray light curve of Vela X-1.

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arXiv2023

The evolution of relative frequencies of ONe and CO SNe Ia

In this population synthesis work we study a variety of possible origin channels of supernovae type Ia (SNe Ia) Among them mergers of carbon-oxygen (CO) and oxygen-neon (ONe) white dwarfs (WDs) under the influence of gravitational waves are considered as the primary channel of SNe Ia formation. We estimated frequencies of mergers of WDs with different chemical compositions and distributions of masses of merging WDs. We computed the dependence of the ratio of merger frequencies of ONe and CO WDs as primaries in corresponding binaries on time. The scatter of masses of considered sources (up to the factor $1.5-2$) of SNe Ia is important and should be carefully studied with other sophisticated methods from theoretical point of view. Our ``game of parameters'' potentially explains the increased dimming of SNe Ia in the redshift range $z\approx 0.5-1$ by the changes in the ratio of ONe and CO WDs, i.e., to describe the observed accelerated expansion of the Universe in terms of the evolution of properties of SNe Ia instead of cosmological explanations. This example shows the extreme importance of theoretical studies of problems concerning SNe Ia, because evolutionary scenario and parameter games in nature potentially lead to confusions in their empirical standardization and, therefore, they can influence on cosmological conclusions.

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arXiv2022

Population synthesis of AX J1745.6-2901 X-ray nova type binaries with rapidly decreasing orbital periods

The neutron star low mass X-ray binary (LMXB) AX J1745.6-2901 was detected an anomalously fast decrease of orbital period. The decreasing rate of orbital period exceeds the contribution of all processes extracting angular momentum from the binary star in standard model. Using SCENARIO MACHINE code we conducted a population synthesis study of X-ray novae with neutron stars to investigate a possible formation and evolution of such binaries. Such close LMXBs should experience a preceding common envelope stage, in which the magnetic fields of the low mass main-sequence donor stars can be dramatically amplified. Our calculations show that the magnetic stellar wind of the optical companion can efficiently extract angular momentum from the binary systems, and produce the observed orbital-period derivatives of AX J1745.6-2901 and black hole LMXBs. The estimated values of the required magnetic field induction are following: $B_\textrm{d}\approx 400$ G (AX~J1745.6-2901), $B_\textrm{d}\approx 1500$ G (KV UMa), $B_\textrm{d}\approx 400$ G (A0620-00), $B_\textrm{d}\approx 1800$ G (Nova Muscae). We successfully reproduced the current observational abundance of such anomalous neutron star X-ray novae, and computed the appropriate value of the parameter of magnetic braking $λ_\textrm{MSW}$ ($0.8-0.6$ for Roche lobe filling stars and $0.4-0.15$ for binaries with partial Roche lobe filling).

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arXiv2020

A comprehensive analysis of NGC 2158 in Gaia era: photometric parameters, apex and orbit

We present an investigation of NGC 2158 using Gaia-DR2 data. We identified 800 most likely cluster members with membership probability higher than 90%. The mean proper motions of this object are determined as (mu_{x}=-0.203 \pm 0.003, mu_{y}=-1.99 \pm 0.004) mas yr^{-1}. The limiting radius, log(age), and distance of the cluster are obtained as 23.5 arcmin, 9.38 \pm 0.04 Gyr and 4.69 \pm 0.22 kpc, respectively. The overall mass function slope (0.93 \pm 0.14) is flatter than the Salpeter value (1.35) within the mass range 1.17-1.44 M_\odot. This cluster also shows the mass-segregation effect and our study demonstrates that NGC 2158 is a dynamically relaxed open cluster. Using the AD-diagram, the apex coordinates of the cluster are obtained in different ways and examined using (μ_{U},μ_{T}) diagram. The best value of apex coordinates is determined as A=87.24^\circ \pm 1.60^\circ, D=-36.61^\circ \pm 5.30 ^\circ. We also determined the orbit of the cluster and found that NGC 2158 moves almost in the Solar antapex direction. The resulting spatial velocity of NGC 2158 is 51 km s^{-1}. A significant oscillations along the Z-coordinate up to 529~pc is detected. Various scenarios regarding the origin of this cluster are also discussed.

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arXiv2020

Evolution of a Viscous Protoplanetary Disk with Convectively Unstable Regions. II. Accretion Regimes and Long-Term Dynamics

In this article, we proceed to study convection as a possible factor of episodic accretion in protoplanetary disks. Within the model presented in Article~I, the accretion history is analyzed at different rates and areas of matter inflow from the envelope onto the disk. It is shown that the burst-like regime occurs in a wide range of parameters. The long-term evolution of the disk is also modeled, including the decreasing-with-time matter inflow from the envelope. It is demonstrated that the disk becomes convectively unstable and maintains burst-like accretion onto the star for several million years. Meanwhile, the instability expands to an area of several tens of astronomical units and gradually decreases with time. It is also shown that at early stages in the disk evolution, conditions arise for gravitational instability in the outer parts of the disk and for dust evaporation in the convectively unstable inner regions. The general conclusion of the study is that convection can serve as one of the mechanisms of episodic accretion in protostellar disks, but this conclusion needs to be verified using more consistent hydrodynamic models.

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arXiv2019

Evolution of a Viscous Protoplanetary Disk with Convectively Unstable Regions

The role of convection in the gas-dust accretion disk around a young star is studied. The evolution of a Keplerian disk is modeled using the Pringle equation, which describes the time variations of the surface density under the action of turbulent viscosity. The distributions of the density and temperature in the polar directions are computed simultaneously in the approximation that the disk is hydrostatically stable. The computations of the vertical structure of the disk take into account heating by stellar radiation, interstellar radiation, and viscous heating. The main factor governing evolution of the disk in this model is the dependence of the viscosity coefficient on the radius of the disk. The computations of this coefficient take into account the background viscosity providing the continuous accretion of the gas and the convective viscosity, which depends on the parameters of the convection at a given radius. The results of computations of the global evolution and morphology of the disk obtained in this approach are presented. It is shown that, in the adopted model, the accretion has burst-like character: after the inner part of the disk ( R < 3 AU) is filled with matter, this material is relatively fast discharged onto the star, after which the process is repeated. Our results may be useful for explaining the activity of young FU Ori and EX Lup objects. It is concluded that convection may be one of the mechanisms responsible for the non-steady pattern of accretion in protostellar disks.

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arXiv2018

Spin of LIGO/VIRGO merging black holes as the result of binary evolution

Recently discovered bursts of gravitational waves provide a good opportunity to verify the current view on the evolution of close binary stars. Modern population synthesis computer programs help to study this evolution from two main sequence stars up to the formation of compact remnants. To calculate the evolution of predecessors of black hole (BH) mergers we used the `Scenario Machine' code. The scenario modelling allowed to describe the evolution of systems for which the final stage is a BH+BH merger and showed the plausibility of modern evolutionary scenarios for binary stars and population synthesis models based on it. We discuss possible values of spins in BH mergers, and give arguments in favour of different values of spins of BH components in BH mergers (low spin + low spin, low spin + high spin, high spin + high spin). We predict that $\geq 50\%$ BH mergers originated through isolated binary evolution should possess spins of both BHs close to zero (low spin + low spin). Up to $\approx$10\% of BH mergers are able to consist of two BHs with spins close to one (high spin + high spin), predecessors of such binaries could be sources of two gamma ray bursts. The BH with the spin close to one could be formed as the result of the merger of two BHs formed via the collapse of a fast rotating star accompanied with a long gamma ray burst and/or a gravitational wave burst with smaller power in comparison with the merger of two BH remnants of binary components.

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arXiv2017

Timing of AB And eclipses

This study aims timing the eclipses of the short period low mass binary star AB And. The times of minima are taken from the literature and from our observations in October 2013 (22 times of minima) and in August 2014 (23 times of minima). We find and discuss an inaccuracy in the determination of the types of minima in the previous investigation by \citet{li2014}. We study the secular evolution of the central binary's orbital period and the possibility of the existence of third and fourth companions in the system.

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arXiv2017

Wolf-Rayet stars, black holes and the first detected gravitational wave source

The recently discovered burst of gravitational waves GW150914 provides a good new chance to verify the current view on the evolution of close binary stars. Modern population synthesis codes help to study this evolution from two main sequence stars up to the formation of two final remnant degenerate dwarfs, neutron stars or black holes [Massevich 1988]. To study the evolution of the GW150914 predecessor we use the "Scenario Machine" code presented by [Lipunov 1996]. The scenario modelling conducted in this study allowed to describe the evolution of systems for which the final stage is a massive BH+BH merger. We find that the initial mass of the primary component can be $100÷140 M_{\odot}$ and the initial separation of the components can be $50÷350 R_{\odot}$. Our calculations show the plausibility of modern evolutionary scenarios for binary stars and the population synthesis modelling based on it.

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arXiv2016

Light equation in eclipsing binary CV Boo: third body candidate in elliptical orbit

A short period eclipsing binary star CV Boo is tested for the possible existence of additional bodies in the system with a help of the light equation method. We use data on the moments of minima from the literature as well as from our observations during 2014 May--July. A variation of the CV Boo's orbital period is found with a period of $\approx 75$ d. This variation can be explained by the influence of a third star with a mass of $\approx 0.4M_{\odot}$ in an eccentric orbit with $e\approx 0.9$. A possibility that the orbital period changes on long time scales is discussed. The suggested tertiary companion is near the chaotic zone around the central binary, so CV Boo represents an interesting example to test its dynamical evolution. A list of 14 minima moments of the binary obtained from our observations is presented.

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arXiv2015

An Exo-Jupiter Candidate in the Eclipsing Binary FL Lyr

Light curves of the eclipsing binary FL Lyr acquired by the Kepler space telescope are analyzed. Eclipse timing measurements for FL Lyr testify to the presence of a third body in the system. Preliminary estimates of its mass and orbital period are > 4M_Jupiter and > 7 yrs. The times of primary minimum in the light curve of FL Lyr during the operation of the Kepler mission are presented.

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arXiv2015

Timing of eclipsing binary V0873 Per: a third body candidate

We analyse a set of moments of minima of eclipsing variable V0873 Per. V0873 Per is a short period low mass binary star. Data about moments of minima of V0873 Per were taken from literature and our observations during 2013-2014. Our aim is to test the system on existence of new bodies using timing of minima of eclipses. We found the periodical variation of orbital period of V0873 Per. This variation can be explained by the gravitational influence of a third companion on the central binary star. The mass of third body candidate is $\approx 0.2 M_{\odot}$, its orbital period is $\approx 300$ days. The paper also includes a table with moments of minima calculated from our observations which can be used in future investigations of V0873 Per.

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arXiv2011

Type Ia Supernovae: Non-standard Candles of the Universe

We analyze the influence of the evolution of light absorption by gray dust in the host galaxies of type Ia supernovae (SNe Ia) and the evolution of the mean combined mass of close-binary carbon-oxygen white dwarfs merging due to gravitational waves (SNe Ia precursors) on the interpretation of Hubble diagrams for SNe Ia. A significant increase in the mean SNe Ia energy due to the higher combined masses of merging dwarfs should be observable at redshifts z > 2. The observed relation between the distance moduli and redshifts of SNe Ia can be interpreted not only as evidence for accelerated expansion of the Universe, but also as indicating time variations of the gray-dust absorption of light from these supernovae in various types of host galaxies, observational selection effects, and the decrease in mean combined masses of merging degenerate dwarfs.

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arXiv2011

Supernovae type Ia: non-standard candles of the Universe

We analyze the influence of the evolution of light absorbtion by grey dust in SNe Ia host galaxies and the influence of the evolution of average total mass of coalescing double carbon-oxygen white dwarfs (progenitors of SNe Ia) under the influence of gravitational radiation on the interpretation of Hubble diagrams of SNe Ia. Significant increase in the average energy of SNe Ia due to increase in the total mass of merging dwarfs can be observed at red shift z> 2. The observed dependence of the distance modulus from the red shift in observations of SNe Ia can be explained not only by the assumption about accelerated expansion of the Universe, but also by the evolution of the absorbtion of light by grey dust in various types of host galaxies of SNe Ia, by the effects of observational selection and by the decrease in the average mass of coalescing degenerate dwarfs.

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arXiv2009

A Mechanism for the Oxygen and Iron Bimodal Radial Distribution Formation in the Disc of our Galaxy

Recently it has been proposed that there are two types of SN Ia progenitors -- short-lived and long-lived. On the basis of this idea, we develope a theory of a unified mechanism for the formation of the bimodal radial distribution of iron and oxygen in the Galactic disc. The underlying cause for the formation of the fine structure of the radial abundance pattern is the influence of spiral arms, specifically, the combined effect of the corotation resonance and turbulent diffusion. From our modelling we conclude that to explain the bimodal radial distributions simultaneously for oxygen and iron and to obtain approximately equal total iron output from different types of supernovae, the mean ejected iron mass per supernova event should be the same as quoted in literature if maximum mass of stars, that eject heavy elements, is $50 M_{\odot}$. For the upper mass limit of $70 M_{\odot}$ the production of iron by a supernova II explosion should be increased by about 1.5 times.

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arXiv2009

Merging of Components in Close Binaries: Type Ia Supernovae, Massive White Dwarfs, and Ap stars

The "Scenario Machine" (a computer code designed for studies of the evolution of close binaries) was used to carry out a population synthesis for a wide range of merging astrophysical objects: main-sequence stars with main-sequence stars; white dwarfs with white dwarfs, neutron stars, and black holes; neutron stars with neutron stars and black holes; and black holes with black holes.We calculate the rates of such events, and plot the mass distributions for merging white dwarfs and main-sequence stars. It is shown that Type Ia supernovae can be used as standard candles only after approximately one billion years of evolution of galaxies. In the course of this evolution, the average energy of Type Ia supernovae should decrease by roughly 10%; the maximum and minimum energies of Type Ia supernovae may differ by no less than by a factor of 1.5. This circumstance should be taken into account in estimations of parameters of acceleration of the Universe. According to theoretical estimates, the most massive - as a rule, magnetic - white dwarfs probably originate from mergers of white dwarfs of lower mass. At least some magnetic Ap and Bp stars may form in mergers of low-mass main sequence stars (<1.5 mass of the Sun) with convective envelopes.

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arXiv2008

Long Gamma-Ray Bursts and the Morphology of their Host Galaxies

We present the results of population syntheses for binary stars carried out using the ``Scenario Machine'' code with the aim of analyzing events that may result in long gamma-ray bursts. We show that the observed distribution of morphological types of the host galaxies of long gamma-ray bursts can be explained in a model in which long gamma-ray bursts result from the core collapse of massive Wolf-Rayet stars in close binaries. The dependence of the burst rate on galaxy type is associated with an increase in the rate of stellar-wind mass-loss with increasing stellar metallicity. The separation of binary components at the end of their evolution increases with the stellar-wind rate, resulting in a reduction of the number of binaries that produce gamma-bursts.

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arXiv2006

Collapse of rotating stars in the Universe and the cosmic gamma ray bursts

We analyze here late evolutionary stages of massive (with initial mass higher than 8 masses of the Sun) close binary stars. Our purposes are to study possible mechanisms of gamma ray bursts (GRBs) origin. We suppose in this paper that GRB phenomenon require formation of massive (approx. 1 M_sun) compact (approx. 10 km) accretion disks around Kerr black holes and neutron stars. Such Kerr black holes are products of collapse of Wolf-Rayet stars in extremely close binaries and merging of neutron stars with black holes and neutron stars with neutron stars in close binary systems. Required accretion disks also can be formed around neutron stars which were formed during collapse of accreting oxygen-neon white dwarfs. We have estimated frequencies of events which lead to a rotational collapse concerned with formation of rapidly rotating relativistic objects in the Galaxy. We made our calculations using the "Scenario Machine".

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