Physical process of tidal synchronization and orbital circularization in rotating binaries

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成果归属作者:

王靖洲

成果归属机构:

理学院

作者

Li, Z ; Song, HF ; Peng, WG ; Wang, JZ ; Zhan, Q

单位

Guizhou Univ, Coll Phys, Guiyang 550025, Guizhou, Peoples R China;Univ Geneva, Dept Astron, CH-1290 Geneva, Switzerland;Kaili Univ, Sch Phys & Elect Engn, Kaili 556011, Peoples R China;Chinese Acad Sci, Key Lab Struct & Evolut Celestial Objects, Kunming 650011, Yunnan, Peoples R China

关键词

close binaries; evolution; rotation; tide

摘要

The tide is a very important physical factor which can significantly affect the structure and evolution of stars. The physical factors which can affect tidal synchronization and orbital circularization are explored in this paper. For stars with radiative envelopes, radiative damping mechanism is required to explain the observed synchronization and circularization of close binaries. A star can experience a range of oscillations that arise from, and are driven by, the tidal field: the dynamical tides. The dynamical tide is the dynamical response to the tidal force exerted by the companion; it takes into account the elastic properties of the star, and the possibilities of resonances with its free modes of oscillation. The dissipation mechanism acting on this kind of tide is the deviation from adiabaticity of the forced oscillation, due to the radiative damping. Several physical factors can have an influence on the process of radiative damping which is scaled with thermal timescale. These physical factors include stellar mass, initial velocity, orbital period, metallicity, overshooting, etc. According to the equations for angular momentum transfer and chemical elements diffusion, we can obtain how these physical factors affect the evolution of rotating binaries and the mixing of chemical elements in two rotating components. The results indicates that the binaries with massive stars, smaller initial spin velocities, smaller overshooting parameters, and shorter orbital periods can attain the equilibrium speed and orbital circularization early. At synchronous states, the tidal torque is zero and stellar winds continue to brake the star. Therefore, two components cannot keep the synchronous state for a long time. At the equilibrium state, the tidal torque is counteracted by wind torques. Therefore, the equilibrium speed is less than the synchronous one. The system with smaller initial spin velocities reaches the equilibrium speed and orbital circularization early because angular momentum transformation between spin and the orbit can shorten the orbital distance and increase the tidal torques. Nitrogen enrichment in binaries is weaker than the one in single stars due to tidal braking. The results reveal that the system with massive components, higher metallicities, larger overshooting parameters, and shorter orbital periods can display high nitrogen enrichment. Stellar radius is small in the star with lower mass, lower metallicities, slower spin speeds and larger overshooting parameters whereas the star with lower metallicities have higher surface effective temperature. Rapid rotating stars evolve towards low temperature and luminosity in the HR diagram.

基金

National Natural Science Foundation of China [11463002, 11863003]; Science and Technology Foundation of Guizhou Province, China [LKK(2013)020]; Open Foundation of the Key Laboratory for the Structure and Evolution of Celestial Objects, Chinese Academy of Science [OP201405]

语种

中文

来源

ACTA PHYSICA SINICA,2018(19):.

收录

SCI(E)

出版日期

2018-10-05

提交日期

2018-12-06

引用参考

Li, Z; Song, HF; Peng, WG; Wang, JZ; Zhan, Q. Physical process of tidal synchronization and orbital circularization in rotating binaries[J]. ACTA PHYSICA SINICA,2018(19):.

  • dc.title
  • Physical process of tidal synchronization and orbital circularization in rotating binaries
  • dc.contributor.author
  • Li, Z; Song, HF; Peng, WG; Wang, JZ; Zhan, Q
  • dc.contributor.affiliation
  • Guizhou Univ, Coll Phys, Guiyang 550025, Guizhou, Peoples R China;Univ Geneva, Dept Astron, CH-1290 Geneva, Switzerland;Kaili Univ, Sch Phys & Elect Engn, Kaili 556011, Peoples R China;Chinese Acad Sci, Key Lab Struct & Evolut Celestial Objects, Kunming 650011, Yunnan, Peoples R China
  • dc.publisher
  • ACTA PHYSICA SINICA
  • dc.identifier.year
  • 2018
  • dc.identifier.issue
  • 19
  • dc.identifier.volume
  • 67
  • dc.date.issued
  • 2018-10-05
  • dc.language.iso
  • 中文
  • dc.contributor.major
  • 物理学
  • dc.subject
  • close binaries; evolution; rotation; tide
  • dc.description.abstract
  • The tide is a very important physical factor which can significantly affect the structure and evolution of stars. The physical factors which can affect tidal synchronization and orbital circularization are explored in this paper. For stars with radiative envelopes, radiative damping mechanism is required to explain the observed synchronization and circularization of close binaries. A star can experience a range of oscillations that arise from, and are driven by, the tidal field: the dynamical tides. The dynamical tide is the dynamical response to the tidal force exerted by the companion; it takes into account the elastic properties of the star, and the possibilities of resonances with its free modes of oscillation. The dissipation mechanism acting on this kind of tide is the deviation from adiabaticity of the forced oscillation, due to the radiative damping. Several physical factors can have an influence on the process of radiative damping which is scaled with thermal timescale. These physical factors include stellar mass, initial velocity, orbital period, metallicity, overshooting, etc. According to the equations for angular momentum transfer and chemical elements diffusion, we can obtain how these physical factors affect the evolution of rotating binaries and the mixing of chemical elements in two rotating components. The results indicates that the binaries with massive stars, smaller initial spin velocities, smaller overshooting parameters, and shorter orbital periods can attain the equilibrium speed and orbital circularization early. At synchronous states, the tidal torque is zero and stellar winds continue to brake the star. Therefore, two components cannot keep the synchronous state for a long time. At the equilibrium state, the tidal torque is counteracted by wind torques. Therefore, the equilibrium speed is less than the synchronous one. The system with smaller initial spin velocities reaches the equilibrium speed and orbital circularization early because angular momentum transformation between spin and the orbit can shorten the orbital distance and increase the tidal torques. Nitrogen enrichment in binaries is weaker than the one in single stars due to tidal braking. The results reveal that the system with massive components, higher metallicities, larger overshooting parameters, and shorter orbital periods can display high nitrogen enrichment. Stellar radius is small in the star with lower mass, lower metallicities, slower spin speeds and larger overshooting parameters whereas the star with lower metallicities have higher surface effective temperature. Rapid rotating stars evolve towards low temperature and luminosity in the HR diagram.
  • dc.description.sponsorship
  • National Natural Science Foundation of China [11463002, 11863003]; Science and Technology Foundation of Guizhou Province, China [LKK(2013)020]; Open Foundation of the Key Laboratory for the Structure and Evolution of Celestial Objects, Chinese Academy of Science [OP201405]
  • dc.identifier.issn
  • 1000-3290
  • dc.description.indexed
  • SCI(E)
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