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Merging strangeon stars Ⅱ:the ejecta and light curves

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research in Astronomy and astrophysics 2021年第10期21卷 86-96页

作者： Xiao-Yu Lai Cheng-Jun Xia) Yun-Wei Yu Ren-Xin Xu Department of Physics and Astronomy Hubei University of EducationWuhan 430205China research Center for Astronomy Hubei University of EducationWuhan 430205China School of Information Science and Engineering NingboTech UniversityNingbo 315100China institute of astrophysics Central China Normal UniversityWuhan 430079China School of Physics Peking UniversityBeijing 100871China kavli institute for Astronomy and astrophysics Peking UniversityBeijing 100871China

The state of supranuclear matter in compact stars remains puzzling,and it is argued that pulsars could be strangeon *** consequences of merging double strangeon stars are worth exploring,especially in the new era of multi-messenger *** develop the"strangeon kilonova"scenario proposed in Paper I,we make a qualitative description about the evolution of ejecta and light curves for merging double strangeon *** the hot environment of the merger,the strangeon nuggets ejected by tidal disruption and hydrodynamical squeezing would suffer from evaporation,in which process particles,such as strangeons,neutrons and protons,are *** into account both the evaporation of strangeon nuggets and the decay of strangeons,most of the strangeon nuggets would turn into neutrons and protons,within dozens of milliseconds after being *** evaporation rates of different particles depend on temperature,and we find that the ejecta could end up with two components,with high and low opacity *** high opacity component would be in the directions around the equatorial plane,and the low opacity component would be in a broad range of angular *** bolometric light curves show that the spin-down power of the long-lived remnant would account for the whole emission of kilonova AT2017gfo associated with GW170817,if the total ejected mass 10^(-3)M⊙.The detailed picture of merging double strangeon stars is expected to be tested by future numerical simulations.

关键词： dense matter equation of state pulsars:general

On the metallicity gradients of the Galactic disk as revealed by LSS-GAC red clump stars

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research in Astronomy and astrophysics 2015年第8期15卷 1240-1263页

作者： Yang Huang Xiao-Wei Liu Hua-Wei Zhang Hai-Bo Yuan Mao-Sheng Xiang Bing-Qiu Chen Juan-Juan Ren Ning-Chen Sun Chun Wang Yong Zhang Yong-Hui Hou Yue-Fei Wang Ming Yang Department of Astronomy Peking University kavli institute for Astronomy and astrophysics Peking University Nanjing institute of Astronomical Optics & Technology National Astronomical ObservatoriesChinese Academy of Sciences Key Laboratory of Optical Astronomy National Astronomical ObservatoriesChinese Academy of Sciences

Using a sample of over 70 000 red clump（RC） stars with 5%–10% distance accuracy selected from the LAMOST Spectroscopic Survey of the Galactic Anti-center（LSS-GAC）, we study the radial and vertical gradients of the Galactic disk（s） mainly in the anti-center direction, covering a significant volume of the disk in the range of projected Galactocentric radius 7 ≤ RGC ≤ 14 kpc and height from the Galactic midplane 0 ≤ ｜Z ｜ ≤ 3 kpc. Our analysis shows that both the radial and vertical metallicity gradients are negative across much of the volume of the disk that is probed, and they exhibit significant spatial variations. Near the solar circle（7 ≤ RGC ≤ 11.5 kpc）, the radial gradient has a moderately steep, negative slope of-0.08 dex kpc-1near the midplane（｜Z ｜〈 0.1 kpc）, and the slope flattens with increasing ｜Z ｜. In the outer disk（11.5 〈 RGC ≤ 14 kpc）, the radial gradients have an essentially constant, much less steep slope of-0.01 dex kpc-1at all heights above the plane, suggesting that the outer disk may have experienced an evolutionary path different from that of the inner disk. The vertical gradients are found to flatten largely with increasing RGC. However, the vertical gradient of the lower disk（0 ≤ ｜Z ｜ ≤ 1 kpc）is found to flatten with RGC quicker than that of the upper disk（1 〈｜Z ｜ ≤ 3 kpc）.Our results should provide strong constraints on the theory of disk formation and evolution, as well as the underlying physical processes that shape the disk（e.g. gas flows,radial migration, and internal and external perturbations）.

关键词： Galaxy: abundances—Galaxy: disk—Galaxy: evolution—Galaxy: formation—techniques: spectroscopic

Asymptotic Magnitude Bode Plots of Fractional-Order Transfer Functions

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IEEE/CAA Journal of Automatica Sinica 2019年第4期6卷 1019-1026页

作者： Ameya Anil Kesarkar Selvaganesan Narayanasamy IEEE the space Applications Centre (SAC) Indian Space Research Organization (ISRO)AhmedabadGujaratIndia the Department of Avionics Indian Institute of Space Science and Technology (IIST)ThiruvananthapuramKeralaIndia

Development of asymptotic magnitude Bode plots for integer-order transfer functions is a well-established topic in the control ***,construction of such plots for the fractional-order transfer functions has not received much attention in the existing *** the present paper,we investigate in this direction and derive the procedures for sketching asymptotic magnitude Bode plots for some of the popular fractional-order controllers such as PI^α,[PI]^α,PD^β,[PD]^β,and PI^αD^β.In addition,we deduce these plots for general fractional commensurate-order transfer functions as *** applications of this work,we illustrate 1)the analysis of the designed fractional-control loop and 2)the identification of fractional-order transfer function from a given plot.

关键词： Asymptotic magnitude Bode commensurateorder fractional-order

spacecraft motion analysis about rapid rotating small body

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Journal of Harbin institute of Technology(New Series) 2003年第4期10卷 363-366页

作者：史雪岩崔祜涛崔平远栾恩杰 Deep space Exploration research Center Harbin Institute of Technology China National space Adminstration

The orbital dynamics equation of a spacecraft around an irregular sphere small body is established based on the small body’s gravitational potential approximated with a tri-axial ellipsoid. According to the Jacobi integral constant, the spacecraft zero-velocity curves in the vicinity of the small body is described and feasible motion region is analyzed. The limited condition and the periapsis radius corresponding to different eccentricity against impact surface are presented. The stability of direct and retrograde equator orbits is analyzed based on the perturbation solutions of mean orbit elements.

关键词： spacecraft orbital dynamics small body

Design of MGA trajectories for main belt asteroid

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Journal of Harbin institute of Technology(New Series) 2003年第4期10卷 443-446页

作者：崔祜涛乔栋崔平远栾恩杰 Deep space Exploration research Center Harbin Institute of Technology China National space Administration

Asteroid exploration is one of the most sophisticated missions currently being investigated. Gravity-assist trajectories have proven valuable in interplanetary missions such as the Pioneer, Voyager and Galileo. In this paper, we design interplanetary trajectory for main belt asteroid exploration mission with the Mars gravity-assist (MGA) using “pork chop” plots and patched-conic theory and give some initial valuable trajectory parameters on main belt asteroid exploration mission with MGA.

关键词： Design trajectory Gravity assist trajectory Rendezvous with asteroid

Jet precession in neutrino-cooled disks for gamma-ray bursts:The effects of the mass and spin of a black hole

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Chinese Physics B 2012年第6期21卷 608-611页

作者：刘彤薛力 Department of Physics and institute of Theoretical Physics and astrophysics Xiamen University

We present a model of jet precession driven by a neutrino-cooled disk around a spinning black hole to explain the quasi-periodic features observed in some gamma-ray burst light curves. The different orientations of the rotational axes between the outer part of a neutrino-cooled disk and a black hole result in precessions of the central black hole and the inner part of the disk. Hence, the jet arising from the neutrino annihilation above the inner disk is driven to precession. We find that the period of precession is positively correlated with the mass as well as the spin of a black hole.

关键词： accretion accretion disks black hole physics gamma rays bursts

Impulsive orbit control for spacecraft around asteroid

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Journal of Harbin institute of Technology(New Series) 2003年第4期10卷 349-352页

作者：崔祜涛崔平远栾恩杰 Deep space Exploration research Center Harbin Institute of Technology China National space Administration

An impulse feedback control law to change the mean orbit elements of spacecraft around asteroid is presented. First, the mean orbit elements are transferred to the osculating orbit elements at the burning time. Then, the feedback control law based on Gauss’s perturbation equations of motion is given. And the impulse control for targeting from the higher circulation orbit to the specified periapsis is developed. Finally, the numerical simulation is performed and the simulation results show that the presented impulse control law is effective.

关键词： Impulse feedback control Mean orbit elements orbit transfer

Gap formation in a self-gravitating disk and the associated migration of the embedded giant planet

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research in Astronomy and astrophysics 2014年第4期14卷 433-455页

作者： Hui Zhang Hui-Gen Liu Ji-Lin Zhou Robert A.Wittenmyer School of Astronomy and space Science & Key Laboratory of Modern Astronomy and astrophysics in Ministry of Education Nanjing University Department of astrophysics School of Physics University of New South Wales

We present the results of our recent study on the interactions between a giant planet and a self-gravitating gas disk. We investigate how the disk＇s self-gravity affects the gap formation process and the migration of the giant planet. Two series of 1-D and 2-D hydrodynamic simulations are performed. We select several surface densities and focus on the gravitationally stable region. To obtain more reliable gravity torques exerted on the planet, a refined treatment of the disk＇s gravity is adopted in the vicinity of the planet. Our results indicate that the net effect of the disk＇s self- gravity on the gap formation process depends on the surface density of the disk. We notice that there are two critical values, ∑I and ∑n. When the surface density of the disk is lower than the first one,∑0 〈 ∑I, the effect of self-gravity suppresses the formation of a gap. When ∑0 〉 ∑I, the self-gravity of the gas tends to benefit the gap formation process and enlarges the width/depth of the gap. According to our 1-D and 2-D simulations, we estimate the first critical surface density to be ∑I ≈ 0.8 MMSN. This effect increases until the surface density reaches the second critical value ∑n- When ∑0 〉 ∑n, the gravitational turbulence in the disk becomes dominant and the gap formation process is suppressed again. Our 2-D simulations show that this critical surface density is around 3.5 MMSN. We also study the associated orbital evolution of a giant planet. Under the effect of the disk＇s self-gravity, the migration rate of the giant planet increases when the disk is dominated by gravitational turbulence. We show that the migration timescale correlates with the effective viscosity and can be up to 104 yr.

关键词： planets and satellites: formation -- planetary systems: formation --planetary systems: protoplanetary disks

Extending the correlation of L_R-L_X to gamma-ray bursts

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research in Astronomy and astrophysics 2015年第5期15卷 617-622页

作者： Jing L Jing-Wen Xing Yuan-Chuan Zou Wei-Hua Lei Qing-Wen Wu Ding-Xiong Wang GXU-NAOC Center for astrophysics and space Sciences Department of PhysicsGuangxi University Guangxi Key Laboratory for Relativistic astrophysics School of Physics Huazhong University of Science and Technology

The well-known correlation between radio luminosity （LR） and X-ray luminosity （Lx）, LR/LX 10^-5, holds for a variety of objects, such as active galactic nuclei, Galactic black holes, solar flares and cool stars. Here we extend the relation to gamma-ray bursts （GRBs） and find that the GRBs also obey a similar LR - LX relation, with a slightly different slope of LR ∝ LX^1.1. This relation implies that the explosions that occur on different scales may have a common underlying origin.

关键词： gamma-ray bursts general -- quasars general -- stars black holes