Rotating Massive Strangeon Stars and X-Ray Plateau of Short GRBs

Strangeon stars,which are proposed to describe the nature of pulsar-like compact stars,have passed various observational tests.The maximum mass of a non-rotating strangeon star could be high,which implies that the remnants of binary strangeon star mergers could even be long-lived massive strangeon stars.We study rigidly rotating strangeon stars in the slowly rotating approximation,using the Lennard-Jones model for the equation of state.Rotation can significantly increase the maximum mass of strangeon stars with unchanged baryon numbers,enlarging the mass-range of long-lived strangeon stars.During spin-down after merger,the decrease of radius of the remnant will lead to the release of gravitational energy.Taking into account the efficiency of converting the gravitational energy luminosity to the observed X-ray luminosity,we find that the gravitational energy could provide an alternative energy source for the plateau emission of X-ray afterglow.The fitting results of X-ray plateau emission of some short gamma-ray bursts suggest that the magnetic dipole field strength of the remnants can be much smaller than that of expected when the plateau emission is powered only by spin-down luminosity of magnetars.

An Asymmetric Galactic Stellar Disk Traced by OB-type Stars from LAMOST DR7

Using 9943 OB-type stars from LAMOST DR7 in the solar neighborhood,we fit the vertical stellar density profile with the model including a single exponential distribution at different positions(R,Φ).The distributions of the scale heights and scale length show that the young disk traced by the OB-type stars is not axisymmetric.The scale length decreases versus the azimuthal angleΦ,i.e.,from.■kpc withΦ=-3°to■kpc withΦ=9°.Meanwhile we find signal of non-symmetry in the distribution of the scale height of the north and south of the disk plane.The scale height in the north side shows signal of flaring of the disk,while that of the south disk stays almost constant around h_(s)=130 pc.The distribution of the displaceeent of the disk plane Z_(0)also shows variance versus the azimuthal angleΦ,which displays significant differences with the warp model constrained by the Cepheid stars.We also test different values for the position of the Sun,and the distance between the Sun and the Galactic center affects the scale heights and the displacement of the disk significantly,but that does not change our conclusion that the disk is not axisymmetric.

On the Identification of N-rich Metal-poor Field Stars with Future Chinese Space Station Telescope

During the long term evolution of globular clusters(GCs), some member stars are lost to the field. The recently found nitrogen-rich(N-rich) metal-poor field stars are promising candidates of these GC escapees, since N enhancement is the fingerprint of chemically enhanced populations in GCs. In this work, we discuss the possibility of identifying N-rich metal-poor field stars with the upcoming Chinese Space Station Telescope(CSST). We focus on the main survey camera with NUV, u, g, r, i, z, y filters and slitless spectrograph with a resolution about 200.The combination of UV sensitive equipment and prominent N-related molecular lines in the UV band bodes well for the identification: the color–color diagram of(u-g) versus(g-r) is capable of separating N-rich field stars from normal halo stars, if metallicity can be estimated without using the information on u-band photometry.Besides, the synthetic spectra show that a signal-to-noise ratio of 10 is sufficient to identify N-rich field stars. In the near future, a large sample of N-rich field stars found by CSST, combined with state-of-the-art N-body simulations will be crucial to deciphering GC-Galaxy co-evolution.

Free Energy of Anisotropic Strangeon Stars

Can pulsar-like compact objects release further huge free energy besides the kinematic energy of rotation?This is actually relevant to the equation of state of cold supra-nuclear matter,which is still under hot debate.Enormous energy is surely needed to understand various observations,such asγ-ray bursts,fast radio bursts and softγ-ray repeaters.In this paper,the elastic/gravitational free energy of solid strangeon stars is revisited for strangeon stars,with two anisotropic models to calculate in general relativity.It is found that huge free energy(>10^(46)erg)could be released via starquakes,given an extremely small anisotropy((p_(t)-p_(r))/p_(r)~10^(-4),with pt/pr the tangential/radial pressure),implying that pulsar-like stars could have great potential of free energy release without extremely strong magnetic fields in the solid strangeon star model.

Period–Luminosity Relationship forδScuti Stars Revisited

The Gaia DR3 parallax approach was used to estimate the absolute parameters of 2375δScuti stars from the ASAS catalog.The selected stars have a variety of observational characteristics,with a higher than 80%probability of beingδScuti stars.We have displayed all the stars in the Hertzsprung-Russell diagram along with theδScuti instability strip,the Zero Age Main Sequence and the Terminal Age Main Sequence.Then,we determined which fundamental and overtone modes each star belongs to using pulsation constant(Q)calculations.In addition,we evaluated the parameters in the Q calculation equation using three machine learning methods,which showed that surface gravity and temperature have the greatest effect on its calculation.The Period-Luminosity(P-L)relationship of theδScuti stars was also revisited.Eventually,using least squares linear regression,we made four linear fits for fundamental and overtone modes and updated their relationships.

Variable Stars in the 50BiN Open Cluster Survey.Ⅲ.NGC 884

Open clusters are the basic building blocks that serve as a laboratory for the study of young stellar populations in the Milky Way.Variable stars in open clusters provide a unique way to accurately probe the internal structure,temporal and dynamical evolutionary stages of individual stars and the host cluster.The most powerful tool for such studies is time-domain photometric observations.This paper follows the route of our previous work,concentrating on a photometric search for variable stars in NGC 884.The target cluster is the companion of NGC869,forming the well-known double cluster system that is gravitationally bound.From the observation run in 2016 November,a total of 9247 B-band CCD images and 8218Ⅴ-band CCD images were obtained.We detected a total of 15 stars with variability in visual brightness,including five Be stars,three eclipsing binaries,and seven of unknown types.Two new variable stars were discovered in this work.We also compared the variable star content of NGC 884 with its companion NGC 869.

Life Origin in the Milky Way Galaxy: III. Spatial Distribution of Overheated Stars in the Solar Neighborhood

A concept of ensemble averaged stellar reactors is developed to study the dynamics of processes occurring in stars, allocated in the ~200 pc solar neighborhood. According to the effective temperature value, four stellar classes are identified, for which the correlation coefficients and standard deviation are counted. The theory of the buoyancy terrestial elements is generalized to stellar systems. It was suggested that stars are over-heated due to the shift parameters of the nuclear processes occurring inside the stars, which leads to the synthesis of transuranium elements until the achievement of a critical nuclear mass and star explosion. The heavy transuranium elements sink downward and are concentrated in the stellar depth layers. The physical explanation of the existence of the critical Chandrasekhar star limit has been offered. Based on the spatial analysis of overheated stars, it was suggested that the withdrawal of the stellar reactor from the equilibrium state is a consequence of extragalactic compression inside the galaxy arm due to the arm spirality (not to be confused with the spirality of the galaxy itself).

On the Surface Helium Abundance of B-type Hot Subdwarf Stars from the WD+MS Channel of Type Ia Supernovae

The origin of intermediate helium (He)-rich hot subdwarfs is still unclear.Previous studies have suggested that some surviving Type Ia supernovae (SNe Ia) companions from the white dwarf+main-sequence (WD+MS)channel may contribute to the intermediate He-rich hot subdwarfs.However,previous studies ignored the impact of atomic diffusion on the post-explosion evolution of surviving companion stars of SNe Ia,leading to the aspect that they could not explain the observed surface He abundance of intermediate He-rich hot subdwarfs.In this work,by taking the atomic diffusion and stellar wind into account,we trace the surviving companions of SNe Ia from the WD+MS channel using the one-dimensional stellar evolution code MESA until they evolve into hot subdwarfs.We find that the surface He-abundances of our surviving companion models during their core He-burning phases are in a range of-1■log(N_(He) N_(H))■0,which are consistent with those observed in intermediate He-rich hot subdwarfs.This seems to further support the notion that it is possible for surviving companions of SNe Ia in the WD+MS channel to form some intermediate He-rich hot subdwarfs.

Revise Thermal Winds of Remnant Neutron Stars in Gamma-Ray Bursts

It seems that the wealth of information revealed by the multi-messenger observations of the binary neutron star(NS)merger event,GW170817/GRB 170817A/kilonova AT2017gfo,places irreconcilable constraints to models of the prompt emission of this gamma-ray burst(GRB).The observed time delay between the merger of the two NSs and the trigger of the GRB and the thermal tail of the prompt emission can hardly be reproduced by these models simultaneously.We argue that the merger remnant should be an NS(last for,at least,a large fraction of 1 s),and that the difficulty can be alleviated by the delayed formation of the accretion disk due to the absorption of high-energy neutrinos emitted by the NS and the delayed emergence of effective viscosity in the disk.Further,we extend the consideration of the effect of the energy deposition of neutrinos emitted from the NS.If the NS is the central object of a GRB with a distance and duration similar to that of GRB 170817A,thermal emission of the thermal bubble inflated by the NS after the termination of accretion may be detectable.If our scenario is verified,it would be of interest to investigate the cooling of nascent NSs.

Probing the Internal Physics of Neutron Stars through the Observed Braking Indices and Magnetic Tilt Angles of Several Young Pulsars

The braking indices of pulsars may contain important information about the internal physics of neutron stars(NSs),such as neutron superfluidity and internal magnetic fields.As a subsequent paper of Cheng et al.,we perform the same analysis as that done in the previous paper to other young pulsars with a steady braking index,n.Combining the timing data of these pulsars with the theory of magnetic field decay,and using their measured magnetic tilt angles,we can set constraints on the number of precession cycles,ξ,which represents the interactions between superfluid neutrons and other particles in the NS interior.For the pulsars considered in this paper,the results show thatξis within the range of a few×10~3 to a few×10~6.Interestingly,for the Crab and Vela pulsars,the constraints onξobtained with our method are generally consistent with that derived from modeling of the glitch rise behaviors of the two pulsars.Furthermore,we find that the internal magnetic fields of pulsar with n<3 may be dominated by the toroidal components.Our results may not only help to understand the interactions between the superfluid neutrons and other particles in the interior of NSs but also be important for the study of continuous gravitational waves from pulsars.

The EOSs and the Blatant Discrepancy in Modelling Massive Neutron Stars: Origin and a Possible Solution Method

Exploring the state of ultra-cold supranuclear dense matter that makes up the cores of massive neutron stars is one of the greatest unresolved problems in modern physics. In this letter, we show that when the interiors of pulsars are made of compressible and dissipative normal matter, the commonly used solution procedures combined with the known EOSs yield widely scattered solutions and poorly determined radii. A remarkable agreement emerges, however, if pulsars harbour cores that are made of incompressible entropy-free superfluids (SuSu-matter) embedded in flat spacetimes. Such supranuclear dense matter should condensate to form false vacua as predicated by non-perterbative QCD vacuum. The solutions here are found to be physically consistent and mathematically elegant, irrespective of the object’s mass. Based thereon, we conclude that the true masses of massive NSs may differ significantly from those revealed by direct observation.

Probing into the Possible Range of the U Bosonic Coupling Constants in Neutron Stars Containing Hyperons

The range of the U bosonic coupling constants in neutron star matter is a very interesting but still unsolved problem which has multifaceted influences in nuclear physics,particle physics,astrophysics and cosmology.The combination of the theoretical numerical simulation and the recent observations provides a very good opportunity to solve this problem.In the present work,the range of the U bosonic coupling constants is inferred based on the three relations of the mass–radius,mass-frequency and mass-tidal deformability in neutron stars containing hyperons using the GM1,TM1 and NL3 parameter sets under the two flavor symmetries of SU(6)and SU(3)in the framework of the relativistic mean field theory.Combined with observations from PSRs J1614-2230,J0348+0432,J2215-5135,J0952-0607,J0740+6620,J0030-0451,J1748-2446ad,XTE J1739-285,GW170817 and GW190814 events,our numerical results show that the U bosonic coupling constants may tend to be within the range from 0 to 20 GeV^(-2)in neutron star containing hyperons.Moreover,the numerical results of the three relations obtained by the SU(3)symmetry are better in accordance with observation data than those obtained by the SU(6)symmetry.The results will help us to improve the strict constraints of the equation of state for neutron stars containing hyperons.

骨科机器人联合Starr骨盆复位架治疗Tile C型骨盆环骨折

目的:探讨骨科机器人联合Starr骨盆复位架治疗Tile C型骨盆环骨折的临床疗效。方法:2019年10月至2021年5月采用机器人联合Starr骨盆复位架治疗14例Tile C型骨盆环骨折患者,男9例,女5例;年龄33~69岁。14例患者均为新鲜闭合骨折且不合并股骨、胫腓骨骨折等损伤。入院后4~7 d完成手术,术中在可透视碳素床,通过Starr骨盆复位架牵引复位骨盆环,联合骨科机器人治疗C型骨盆环骨折。观察手术时间、出血量、单枚螺钉置入透视次数、骨折复位质量、患肢功能及并发症等。采用Matta评分标准进行放射学复位评价,末次随访采用Majeed骨盆功能评分系统进行临床疗效评价。结果:14例患者均顺利完成手术,手术时间84~141 min,手术出血量20~50 ml,单枚螺钉置入透视次数4~9次。14例患者均获得随访,随访时间12~24个月。术后所有骨折获得骨性愈合,愈合时间3~7个月,未发现内固定断裂、螺钉松动、感染、神经损伤等并发症。依据Matta影像学复位评估标准:优9例,良4例,可1例。末次随访采用Majeed骨盆功能评分系统:优10例,良4例。结论:机器人联合Starr骨盆复位架治疗C型骨盆环新鲜骨折操作简单、缩短了手术和麻醉时间、并发症少,降低了手术风险,实现了骨盆骨折的微创治疗。但对于陈旧性骨折,因骨折复位困难,该技术并不适用。对于螺钉进钉点区域粉碎的骨折,通道螺钉置入困难,建议采用其他方式固定。对于伴有骨盆外伤史或骨盆发育异常者,术前需仔细评估有无经皮螺钉通道,避免损伤神经、血管。

Bayesian inference of the crust–core transition density via the neutron-star radius and neutron-skin thickness data

In this work,we perform a Bayesian inference of the crust-core transition density ρ_(t) of neutron stars based on the neutron-star radius and neutron-skin thickness data using a thermodynamical method.Uniform and Gaussian distributions for the ρ_(t) prior were adopted in the Bayesian approach.It has a larger probability of having values higher than 0.1 fm^(−3) for ρ_(t) as the uniform prior and neutron-star radius data were used.This was found to be controlled by the curvature K_(sym) of the nuclear symmetry energy.This phenomenon did not occur if K_(sym) was not extremely negative,namely,K_(sym)>−200 MeV.The value ofρ_(t) obtained was 0.075_(−0.01)^(+0.005) fm^(−3) at a confidence level of 68%when both the neutron-star radius and neutron-skin thickness data were considered.Strong anti-correlations were observed between ρ_(t),slope L,and curvature of the nuclear symmetry energy.The dependence of the three L-K_(sym) correlations predicted in the literature on crust-core density and pressure was quantitatively investigated.The most probable value of 0.08 fm^(−3) for ρ_(t) was obtained from the L-K_(sym) relationship proposed by Holt et al.while larger values were preferred for the other two relationships.

STAR基因与东湖杂交奶绵羊繁殖性状的关联分析

本实验旨在探究类固醇激素合成急性调节蛋白(Steroidogenic Acute Regulatory Protein,STAR)基因多态性与东湖杂一代奶绵羊发情鉴定评分、产羔数的相关性,鉴定出影响绵羊繁殖性能的关键性位点。本研究以339只东湖杂一代奶绵羊为研究对象,采用竞争性等位基因特异性PCR(KASP)技术对STAR基因的g.31959747T>C、g.31959875A>C2个位点进行基因分型,并利用GLM模型对SNP位点与发情鉴定评分和产羔数进行关联分析。结果表明,g.31959747T>C与奶绵羊发情鉴定评分呈极显著相关,TT型的发情表现更优,但与产羔数差异不显著;g.31959875A>C与发情评分和产羔数均无显著关系;聚合基因型与繁殖性状的关联分析结果表明,TCAC型个体在发情评分、平均产羔数方面均较低。综上,STAR基因g.31959747T>C位点是影响奶绵羊发情评分的关键性位点,可根据育种目标将g.31959747T>C位点作为提高奶绵羊同期发情效果的分子标记,同时将TCAC聚合基因型及时淘汰。本研究结果可为奶绵羊繁殖性状的选育提供参考。

日本沼虾StAR基因克隆及其低氧胁迫下表达分析

为了研究类固醇激素合成急性调节蛋白(steroidogenic acute regulatory protein, StAR)在日本沼虾应答低氧胁迫过程中所发挥的作用,实验应用c DNA末端快速扩增(RACE)PCR技术克隆了日本沼虾StAR全长cDNA序列,并利用在线软件对其序列特征进行生物信息学分析,采用半定量RT-PCR方法分析StAR在日本沼虾不同组织的分布情况,采用实时荧光定量PCR(qRT-PCR)与免疫印迹(Western blot)技术对其在不同低氧胁迫阶段中的表达规律进行检测,观察低氧胁迫下精巢组织中StAR蛋白免疫组化定位。结果显示,日本沼虾StAR其cDNA全长3 361 bp (NCBI登录号:MW263908),包括5′-UTR 323 bp,3′-UTR 2 129 bp,开放阅读框909 bp,编码302个氨基酸。氨基酸序列比对及系统进化分析结果显示,日本沼虾StAR基因与三疣梭子蟹等甲壳动物StAR聚类一支,具有最近的亲缘关系。半定量RT-PCR检测结果显示,StAR在日本沼虾不同组织中均有表达,其表达量在肝胰腺和心脏组织中最低,在精巢组织中表达处于较高水平。使用qRT-PCR技术检测日本沼虾精巢中StAR在低氧胁迫下时空表达情况,结果表明,与对照组相比,低氧处理组精巢中StAR基因表达量在1~48 h均显著上调,而在低氧处理组96 h显著降低。此外,本实验对StAR进行了原核表达及抗血清制备,采用Western blot检测StAR蛋白表达丰度基本与基因表达模式相似,免疫组化结果显示,StAR蛋白在精细胞与间质细胞中均有表达。综上所述,长期低氧胁迫显著降低了StAR基因的转录表达水平,并且该基因可能在类固醇合成路径及精子发生过程中均发挥重要作用。本研究结果为进一步解析日本沼虾类固醇激素合成分子机制奠定基础。

STAR基因在不同发育期绵羊睾丸和附睾中的表达与组织分布

为探讨STAR基因在发育的绵羊睾丸和附睾中的表达模式及潜在功能,该研究采集3月龄、 1周岁和3周岁藏绵羊睾丸和附睾(头、体和尾)组织样本,利用实时荧光定量PCR、蛋白免疫印迹和免疫组织荧光染色法检测STAR基因的表达及其编码蛋白的细胞定位。结果发现,随着年龄的增加,在藏绵羊睾丸和附睾(附睾头除外)中STAR基因在转录水平的表达总体呈下降趋势,而在蛋白质水平的表达呈上调趋势。STAR蛋白主要存在于藏绵羊睾丸间质细胞和附睾假复层纤毛上皮主细胞。鉴于间质细胞和主细胞的主要生物学功能是分泌睾酮和分泌促进精子成熟所需的蛋白质,由此推测,STAR基因可能主要在睾丸间质细胞和附睾主细胞的发育和功能维持中发挥作用,进而促进雄激素的合成和精子的成熟。

Influence of strong magnetic field on β decay in the crusts of neutron stars

β decay in the strong magnetic field of the crusts of neutron stars is analysed by an improved method. The reactions ^67Ni（β-）^67Cu and ^62Mn（β-）^62Fe are investigated as examples. The results show that a weak magnetic field has little effect on β decay but a strong magnetic field （B 〉 10^12G） increases β decay rates obviously. The conclusion derived may be crucial to the research of late evolution of neutron stars and nucleosynthesis in r-process.

R-mode instability of strange stars and observations of neutron stars in LMXBs

Using a realistic equation of state （EOS） of strange quark matter, namely, the modified bag model, and considering the constraints on the parameters of EOS by the observational mass limit of neutron stars, we investigate the r-mode instability window of strange stars, and find the same result as in the brief study of Haskell, Degenaar and Ho in 2012 that these instability windows are not consistent with the spin frequency and temperature observations of neutron stars in low mass X-ray binaries.

Long-term evolution and gravitational wave radiation of neutron stars with differential rotation induced by r-modes

In a second-order r-mode theory, Sa and Tome found that the r-mode oscillation in neutron stars （NSs） could induce stellar differential rotation, which naturally leads to a saturated state of the oscillation. Based on a consideration of the coupling of the r-modes and the stellar spin and thermal evolution, we carefully investigate the influences of the differential rotation on the long-term evolution of isolated NSs and NSs in low-mass X-ray binaries, where the viscous damping of the r-modes and its resultant effects are taken into account. The numerical results show that, for both kinds of NSs, the differential rotation can significantly prolong the duration of the r-modes. As a result, the stars can keep nearly a constant temperature and constant angular velocity for over a thousand years. Moreover, the persistent radiation of a quasi-monochromatic gravitational wave would also be predicted due to the long-term steady r-mode oscillation and stellar rotation. This increases the detectability of gravitational waves from both young isolated and old accreting NSs.