On the influence of mass loss and convective overshooting on the evolution of massive stars     

A. G. Massevitch  E. I. Popova  A. V. Tutukov  L. R. Yungelson 《Astrophysics and Space Science》1979,62(2):451-463

Evolution of massive stars losing mass with the rateM H L/V C is computed (for =1,2,7). It is shown that observed mass loss rates correspond to 0.3 and, therefore, mass loss by stellar wind cannot play any significant role in the evolution of normal massive stars. However, for several types of massive stars (WR, OH/IR, X-ray sources) enhanced mass loss explains their peculiar features. Computations of evolutionary sequences of massive stars with convective overshooting taken into account (as a formal increase of the convective core) show that a significant broadening of the hydrogen-burning band in the H-R diagram may be obtained.  相似文献   

Study of physical properties of spectroscopic binary stars     

E. I. Popova  A. V. Tutukov  L. R. Yungelson 《Astrophysics and Space Science》1982,88(1):55-80

The main results of a study of a catalogue of physical parameters of 1041 spectroscopic binaries are presented. The distribution of spectroscopic binaries over all main parametersM ₁, a, e, M₁/M₂, P, and certain dependencies between some of them have been found.

1. It appears that among bright (m _v?3 ^m –5 ^m ) stars withM?1M _⊙, about 40% are apparently spectroscopic binaries with comparable masses of components.
2. The majority of spectroscopic binaries with the ratio of the large semiaxis of the orbit to the radius of the primarya/R ₁?20, have eccentricities close to zero. This is probably a consequence of the tidal circularization of orbits of close binaries by viscous friction.
3. The discovery of duplicity of double-line spectroscopic binaries is possible only if the semiamplitude of radial velocityK ₁ is almost 10 times higher than the semiamplitude of the radial velocity of a single-line spectroscopic binary of the same mass.
4. Double-line spectroscopic binaries witha/R _⊙?6(M ₁/M _⊙)^1/3,M ₁≈M ₂?1.5M _⊙ are almost almost absent, and the number of stars witha/R _⊙?6(M ₁/M _⊙)^1/3,M ₁≈1.5M _⊙ is relatively low.
5. The distribution of unevolved SB stars over the large semiaxis may be described by the expression d(N _d/N_t)≈0.2 d loga for 6(M ₁/M _⊙)^1/3?a/R _⊙?100.
6. The intial mass-function for primaries of spectroscopic binaries is the same Salpeter function dN _d≈M ₁ ^?2.35 dM ₁ for 1?M ₁/M _⊙?30.
7. It is possible to explain the observed ratio of the number of single-line spectroscopic binaries to the number of double-line binaries if one assumes that the average initial mass ratio is close to 1 and that the mass of the postmass-exchange remnant of the primary exceeds the theoretical one and/or that half of the angular momentum of the system is lost during mass-exchange.
8. The above-mentioned distributions ofM ₁ anda and assumptions on the mass of remnant and/or momentum loss also allow us to explain the observed shapes of dN/dM, dN/dq, and dN/da distributions after some selection effects are taken into account.

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Halo white dwarfs and the evolution of the galaxy     

D. S. Wiebe  A. V. Moiseev  Ya. A. Tikhonov  A. V. Tutukov  B. M. Shustov 《Astronomy Reports》2006,50(1):23-30

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Massive close binary stars and gamma-ray bursts     

A. V. Tutukov  A. M. Cherepashchuk 《Astronomy Reports》2004,48(1):39-44

We analyze the observed parameters of massive extremely close binaries containing Wolf-Rayet stars and black holes, and identify those systems whose supernova outbursts lead to the formation of rapidly rotating Kerr black holes. It is proposed that the formation of such a black hole is accompanied by a strong gamma-ray burst. Several types of observed systems satisfy the conditions necessary for the formation of a Kerr black hole: BH+WR, BH+OB, WR+O, and BH+K,M.  相似文献   

Formation of supermassive black holes due to the tidal deceleration of stellar black holes, globular clusters, and galaxies     

A. V. Tutukov 《Astronomy Reports》2005,49(1):13-23

The formation and evolution of supermassive (10²?10¹⁰ M _⊙) black holes (SMBHs) in the dense cores of globular clusters and galaxies is investigated. The raw material for the construction of the SMBHs is stellar black holes produced during the evolution of massive (25?150M _⊙) stars. The first SMBHs, with masses of ～1000M _⊙, arise in the centers of the densest and most massive globular clusters. Current scenarios for the formation of SMBHs in the cores of globular clusters are analyzed. The dynamical deceleration of the most massive and slowly moving stellar-mass (< 100M _⊙) black holes, accompanied by the radiation of gravitational waves in late stages, is a probable scenario for the formation of SMBHs in the most massive and densest globular clusters. The dynamical friction of the most massive globular clusters close to the dense cores of their galaxies, with the formation of close binary black holes due to the radiation of gravitational waves, leads to the formation of SMBHs with masses ? 10³ M _⊙ in these regions. The stars of these galaxies form galactic bulges, providing a possible explanation for the correlation between the masses of the bulge and of the central SMBHs. The deceleration of the most massive galaxies in the central regions of the most massive and dense clusters of galaxies could lead to the appearance of the most massive (to 10¹⁰ M _⊙) SMBHs in the cores of cD galaxies. A side product of this cascade scenario for the formation of massive galaxies with SMBHs in their cores is the appearance of stars with high spatial velocities (> 300 km/s). The velocities of neutron stars and stellar-mass black holes can reach ～10⁵ km/s.  相似文献   

Destruction of a Star during the Evolution of a Star + Supermassive Black Hole System     

Fedorova  A. V.  Tutukov  A. V. 《Astronomy Reports》2021,65(2):95-109

Astronomy Reports - Stars located closely to supermassive black holes (SMBHs) can, under certain conditions, form close binary systems with the SMBHs, in which the star may fill the Roche lobe and...  相似文献   

Destruction of Galaxies as a Cause of the Appearance of Stellar Streams     

Tutukov  A. V.  Vereshchagin  S. V.  Sizova  M. D. 《Astronomy Reports》2021,65(11):1085-1101

Astronomy Reports - The interaction of galaxies in clusters with the intergalactic gaseous medium and other galaxies is considered. The causes for the appearance of gaseous and stellar...  相似文献   

The radial gradient of heavy-element abundances in disk galaxies     

D. S. Wiebe  A. V. Tutukov  B. M. Shustov 《Astronomy Reports》2001,45(11):854-860

Various origins for the formation of the heavy-element abundance gradients observed in nearly all disk galaxies are analyzed in the framework of evolutionary models. In an isolated galaxy, there is a radial gradient of the abundance of heavy elements only early in its evolution (the first several billion years), which subsequently practically disappears. The gradients of chemical compositions of young objects and the interstellar gas require that typical disk galaxies be open systems (i.e., that they eject some heavy elements into circumgalactic space and/or accrete intergalactic gas) and that the rates of both processes be dependent on galactocentric distance.  相似文献   

Evolution of stars with high metallicities     

A. V. Tutukov  A. V. Fedorova 《Astronomy Reports》2001,45(11):882-887

We have calculated evolutionary tracks for stars with high abundances of heavy elements. An abundance increase from the solar level (～0.02) to 0.1 (for ΔY/ΔZ=0–2.4), which corresponds to the central regions of the disk components of giant galaxies, shifts the main sequence towards lower effective temperatures; however, it does not appreciably affect either the luminosity of the stars or their lifetime on the main sequence. Increasing the heavy-element abundance to 0.2 for ΔY/ΔZ=2.4 shifts the main sequence towards higher effective temperatures, appreciably increases the luminosity of the stars, and substantially accelerates their evolution.  相似文献   

Question of the origin and stage of evolution of the symbiotic stars     

A. V. Tutukov  L. R. Yungel'son 《Astrophysics》1976,12(3):342-348

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