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DISK accretion ONTO MAGNETIC NEUTRON STARS

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南京大学学报(自然科学) 1995年第1期 178-179页

作者： Li Xiangdong Wang Zhenru(Department of Astronomy, Nanjing University, 210093, Nanjing, PRC)

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关键词： X-ary pulsars accretion

Wave Propagation in accretion Disks with Self-Gravity

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Chinese Physics Letters 2001年第2期18卷 301-303页

作者：刘晓慈杨兰田吴少平丁世学 Department of Physics and Institute of AstrophysicsHuazhong Normal UniversityWuhan 430079 Department of Physics Hainan Normal CollegeHaikou 571158 Department of Physics Xiangfan Normal CollegeXiangfan 441053

We extend the research by Lubow and Pringle of axisymmetric waves in accretion disks to the case where self-gravity of disks should be considered.We derive and analyse the dispersion relations with the effect of self-gravity.Results show that self-gravity extends the forbidden region of the wave propagation:for high frequency p-modes,self-gravity makes the wavelength shorter and the group velocity larger;for low frequency g-modes,the effect is opposite.

关键词： accretion effect shorter

SUBDUCTION AND accretion TECTONICS OF HIMALAYAN AND KARAKORAM TERRANES AND THEIR PALAEOGEOLOGIC CONFIGURATION

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地学前缘 2000年第S1期7卷 86-87页

作者： Anshu K. Sinha (Birbal Sahni Institute of Palaeobotany,Under Department of Science & Technology, Government of India,Lucknow 226007, India)

he 2500km long Indus\|Tsangpo Suture has been recognized as one of the best examples of continent to continent collisional Suture Zone. It has come into existence as a result of subduction followed by continental collision (55～60Ma) between Indian (Sinha, 1989, 1997; Sinha et al., 1999) and Eurasian plates. While considering the recent palaeogeographic reconstruction of Pangea during late Palaeozoic it appears that a southern belt of Asian microcontinents stretching from Iran and Afghanistan through southern Tibet to western Thailand, Malaysia and Sumatra, comprise several continental blocks and numerous fragments that have coalesced since the Mid\|Palaeozoic along with the closure of Tethys. The origin, migration, assembly and timing of accretion of all these blocks to their present geotectonic position is not well known and there is no Permo—Triassic crust left in the present day Indian Ocean. The oldest ocean crust adjacent to the west African and Antarctic margin is of early or middle Cretaceous age (approximately 140～100Ma) (Searle, 1991). The Karakoram\|Hindukush microplate in the west and the Qiangtang\|Lhasa block in the central and eastern segment of South Asia margin are among those blocks already welded with Asian plates around 120～130Ma ago, before the collision of India (55～60Ma) with the collage of plates forming Peri\|Gondwanian microcontinents. But the reconstruction of palaeogeographic configuration remain incomplete due to paucity of authentic geologic information available from Karakoram, Pamir and Western Tibet. Prior to our discovery no early Permian plant remains and palynomorphs were ever reported from Karakoram terrane. Our discovery of Early Permian remains and late Asselian (about 280～275Ma) palynomorphs provides crucial clue regarding the palaeogeographic reconstruction of the Karakoram\|Himalayan block in the Permian time.

关键词： collisional suture zone Karakoram subduction accretion

Luminosity Limit of Super-Eddington accretion onto Black Holes

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Chinese Physics Letters 1999年第6期16卷 467-468页

作者：王建民 Department of Astronomy Beijing Normal UniversityBeijing 100875 Chinese Academy of Sciences-Peking University Joint Beijing Astrophysical Center Beijing 100871

The luminosity limit is derived for the super-Eddington accretion by obtaining the self-similar solution.The maximum luminosity is about 4.0×10^(37) erg/s(M/M_(⊙))or so(significantly less than the Eddington luminosity)due to photon trapping although the accretion rate is super-Eddington.The radiation spectrum is found to be universal as F_(v) α v^(-1).

关键词： accretion solution luminosity

Radiation and Vertical Structure of Slim accretion Disk

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Chinese Physics Letters 1999年第7期16卷 544-546页

作者：王建民卢方军周又元 Department of Astronomy Beijing Normal UniversityBeijing 100875 CAS-PKU Joint Beijing Astrophysical Center Peking UniversityBeijing 100871 Laboratory for High Energy Astrophysics Institute of High Energy PhysicsChinese Academy of SciencesBeijing 100039 Center for Astrophysics University of Science and Technology of ChinaHefei 230026

The vertical structure of the disk should be specified in order to compare the theoretical model with the observed spectrum of active galactic nuclei.AH the existing calculations of vertical structure of the accretion disk were based on the standard model.In this paper the vertical structure of the slim disk is calculated,which may be suitable for wider ranges of parameters.The spectrum for higher accretion rate tends to the universal form Fv oc z/-1 and the universal cutoff energy,which is consistent with the self^similar solution for the case with a super-Eddington accretion rate.

关键词： accretion parameters. galactic

Deceleration Effect of Magnetic Field on Black Hole accretion Disks

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Chinese Physics Letters 2000年第2期17卷 148-150页

作者：汪定雄 Department of Physics Huazhong University of Science and TechnologyWuhan 430074

The deceleration effect of magnetic field near the horizon of a spinning black hole (BH) of accretion disk is investigated in the Blandford-Znajek (BZ) process. It is shown that rates of change with respect to time for both the angular velocities of BH horizon and accreting particles at the inner edge of an accretion disk are reduced in the BZ process, behaving with non-monotonous evolution characteristics. This result implies that the magnetic field near the BH horizon has & deceleration effect not only on the spinning BH but also on the surrounding accretion disk.

关键词： horizon accretion process.

State Transitions of Black Hole accretion Flows

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Chinese Physics Letters 2001年第9期18卷 1294-1296页

作者：卢炬甫潘刘彬 Department of Physics Xiamen UniversityXiamen 361005 Center for Astrophysics University of Science and Technology of ChinaHefei 230026

We show that the thermal instability-triggered transition from the state of the Shakura-Sunyaev disc to the state of the advection-dominated accretion flow is possible for black hole accretion flows composed of two-te... 详细信息

关键词： accretion dominated Transition

Entropy Change of Black Holes in Disk-accretion

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Chinese Physics Letters 1999年第6期16卷 464-466页

作者：汪定雄戴廖仲 Department of Physics Huazhong University of Science and TechnologyWuhan 430074

Entropy change of central black holes of accretion disks(including thin and thick disks)is investigated by considering both accretion and the Blandford-Znajek(BZ)process in detail.It is shown that the contribution of the BZ process to the rate of change of black hole entropy is always less than that arising from accretion process in the case of thin disks,while the former may be greater than the latter for a fast-spinning black hole surrounded by a thick disk.In addition the non-monotonic characteristics of the rate of change of black hole entropy in the BZ process are discussed.

关键词： thick accretion black

Axisymmetric Waves in Isothermal accretion Discs with Vertical Self-Gravity

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Communications in Theoretical Physics 2001年第12期36卷 743-748页

作者： LIU Xiao-Ci YANG Lan-Tian WU Shao-Ping DING Shi-Xue Department of Physics Hainan Normal College Haikou 571158 Hainan Province Chinat Department of Physics and Institute of Astrophysics Huazhong Normal University Wuhan 430079 China Department of Physics and Institute of Astrophysics Huazhong Normal University Wuhan 430079 China Department of Physics and Institute of Astrophysics Huazhong Normal University Wuhan 430079 China Department of Physics and Institute of Astrophysics Huazhong Normal University Wuhan 430079 China Department of Physics Xiangfan Normal College Xiangfan 441053 Hubei Province China

We extend the research of axisymmetric waves in accretion discs with three-dimensional structure to the case that vertical self-gravity of the discs is included. We derive and analyze the dispersion relation and solve the eigenfunctions numerically. The following results have been reached: vertical self-gravity expands the forbidden region of the wave propagation. As the influence of the vertical self-gravity increases, the group velocities of the waves get smaller and the vertical nodes of the wave shrink to the middle plane of the disc.

关键词： accretion, accretion discs, hydrodynamics, waves