Formation of a Rapidly Rotating Classical Be-star in a Massive Close Binary System

This paper investigates the spin-up of a mass-accreting star in a close binary system passing through the first stage of mass exchange in the Hertzsprung gap. Inside an accreting star, angular momentum is carried by meridional circulation and shear turbulence. The circulation carries part of the angular momentum of the accreted layers to the accretor's surface. The greater the rate of arrival of angular momentum in the accretor is, the greater this part. It is assumed that this part of the angular momentum can be removed by the disk further from the accretor. If the angular momentum in the matter entering the accretor is more than half the Keplerian value, then the angular momentum obtained by the accretor during mass exchange stage does not depend on the rate of arrival of angular momentum. The accretor may have the characteristics of a Be-star immediately after the end of mass exchange.

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.

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.

New Cases of Superflares on Slowly Rotating Solar-type Stars and Large Amplitude Superflares in G-and M-type Main Sequence Stars

In our previous work,we searched for superflares on different types of stars while focusing on G-type dwarfs using entire Kepler data to study statistical properties of the occurrence rate of superflares.Using these new data,as a byproduct,we found 14 cases of superflare detection on 13 slowly rotating Sun-like stars with rotation periods of24.5–44 days.This result supports the earlier conclusion by others that the Sun may possibly undergo a surprise superflare.Moreover,we found 12 and seven new cases of detection of exceptionally large amplitude superflares on six and four main sequence stars of G-and M-type,respectively.No large-amplitude flares were detected in A,F or K main sequence stars.Here we present preliminary analysis of these cases.The superflare detection,i.e.,an estimation of flare energy,is based on a more accurate method compared to previous studies.We fit an exponential decay function to flare light curves and study the relation between e-folding decay time,τ,versus flare amplitude and flare energy.We find that for slowly rotating Sun-like stars,large values ofτcorrespond to small flare energies and small values ofτcorrespond to high flare energies considered.Similarly,τis large for small flare amplitudes andτis small for large amplitudes considered.However,there is no clear relation between these parameters for large amplitude superflares in the main sequence G-and M-type stars,as we could not establish clear functional dependence between the parameters via standard fitting algorithms.

The Neutron Star to Black Hole Mass Gap in the Frame of the Jittering Jets Explosion Mechanism(JJEM)

I build a toy model in the frame of the jittering jets explosion mechanism(JJEM)of core collapse supernovae that incorporates both the stochastically varying angular momentum component of the material that the newly born neutron star(NS)accretes and the constant angular momentum component,and show that the JJEM can account for the≃2.5–5M⊙mass gap between NSs and black holes(BHs).The random component of the angular momentum results from pre-collapse core convection fluctuations that are amplified by post-collapse instabilities.The fixed angular momentum component results from pre-collapse core rotation.For slowly rotating pre-collapse cores the stochastic angular momentum fluctuations form intermittent accretion disks(or belts)around the NS with varying angular momentum axes in all directions.The intermittent accretion disk/belt launches jets in all directions that expel the core material in all directions early on,hence leaving an NS remnant.Rapidly rotating pre-collapse cores form an accretion disk with angular momentum axis that is about the same as the pre-collapse core rotation.The NS launches jets along this axis and hence the jets avoid the equatorial plane region.Inflowing core material continues to feed the central object from the equatorial plane increasing the NS mass to form a BH.The narrow transition from slow to rapid pre-collapse core rotation,i.e.,from an efficient to inefficient jet feedback mechanism,accounts for the sparsely populated mass gap.

Main Sequence Star Super-flare Frequency based on Entire Kepler Data

We wrote and used an automated flare detection Python script to search for super-flares on main sequence stars of types A,F,G,K and M in Kepler's long-cadence data from Q0 to Q17.We studied the statistical properties of the occurrence rate of super-flares.For the G-type data set,we compared our results with the previous results of Okamoto et al.by splitting the data set into four rotational bands.We found similar power-law indices for the flare frequency distribution.Hence,we show that inclusion of a high-pass filter,sample biases,gyrochronology and completeness of flare detection is of no significance,as our results are similar to those of Okamoto et al.We estimated that a super-flare on G-type dwarfs with energy of 10^(35) erg occurs on a star once every 4360 yr.We found 4637 super-flares on 1896 G-type dwarfs.Moreover,we identified 321,1125,4538 and 5445 super-flares on 136,522,770 and 312 dwarfs of types A,F,K and M,respectively.We ascertained that the occurrence rate(dN/dE)of super-flares versus flare energy,E,shows a power-law distribution with dN/dE∝E^(-α),whereα■2.0 to 2.1 for the spectral types from F-type to M-type stars.In contrast,the obtainedα■1.3 for A-type stars suggests that the flare conditions differ from those of the other spectral-type stars.We note an increase in flare incidence rate in F-type to M-type stars and a decrease in A-type to F-type stars.

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。

Early Phases of Star Formation: Testing Chemical Tools

Star-forming processes strongly influence the ISM chemistry.Nowadays,many high-quality databases are available at millimeter wavelengths.Using them,it is possible to carry out studies that review and deepen previous results.If these studies involve large samples of sources,it is preferred to use direct tools to study the molecular gas.With the aim of testing these tools such as the use of the HCN/HNC ratio as a thermometer,and the use of H^(13)CO^(+),HC_(3)N,N_(2)H^(+) and C_(2)H as "chemical clocks," we present a molecular line study toward 55 sources representing massive young stellar objects at different evolutionary stages:infrared dark clouds(IRDCs),highmass protostellar objects(HMPOs),hot molecular cores(HMCs) and ultracompact H II regions.We found that the use of the HCN/HNC ratio as a universal thermometer in the ISM should be taken with care because the HCN optical depth is a big issue that can affect the method.Hence,this tool should be utilized only after a careful analysis of the HCN spectrum,checking that no line,neither the main nor the hyperfine ones,presents absorption features.We point out that the analysis of the emission of H^(13)CO^(+),HC_(3)N,N_(2)H^(+) and C_(2)H could be useful to trace and distinguish regions among IRDCs,HMPOs and HMCs.The molecular line widths of these four species increase from the IRDC to the HMC stage,which can be a consequence of the gas dynamics related to the starforming processes taking place in the molecular clumps.Our results not only contribute with more statistics,acting as a probe of such chemical tools,useful to obtain information in large samples of sources,but also complement previous works through the analysis of other types of sources.

Starlinger新版RecoSTAR回收产线即将亮相CHINAPLAS 2024

来自奥地利的史太林格回收技术公司(Starlinger Recycling Technology)将在CHINAPLAS 2024国际橡塑展展示其recoSTAR动态回收生产线解决方案。该方案可用于加工消费后塑料,如聚乙烯、聚丙烯和聚苯乙烯等。采用高真空脱气或减少气味等特殊技术来生产高质量再生粒料,这些回收料可再次用于包装加工。recoSTAR回收生产线可处理潮湿和吸湿材料、重度印刷薄膜和高度污染塑料,其专门开发的C-VAC脱气模块可有效地去除气体,防止空气卷入回收粒料内。本次展示的新型recoSTAR PET art机器概念建立在史太林格公司超过15年的制造聚对苯二甲酸乙二醇酯(PET)瓶到瓶回收生产线的基础上,旨在将机械PET回收提升到一个新水平。

Possible Habitats for NH_(3),NH_(2)D,H^(13)CN,HC^(15)N,SO,and C^(18)O in the Initial Conditions of High-mass Star Formation

The initial condition of high-mass star formation is a complex area of study because of the high densities(n_(H_(2))>106cm^(-3))and low temperatures(T_(dust)<18 K)involved.Under such conditions,many molecules become depleted from the gas phase by freezing out onto dust grains.However,the N-bearing and deuterated species could remain gaseous under these extreme conditions,suggesting that they may serve as ideal tracers.In this paper,using the Plateau de Bure Interferometer and Very Large Array observations at 1.3 mm,3.5 mm,and 1.3 cm,we investigate the possible habitats for NH_(3),NH_(2)D,H^(13)CN,HC^(15)N,SO,and C^(18)O in eight massive precluster and protocluster clumps G18.17,G18.21,G23.97N,G23.98,G23.44,G23.97S,G25.38,and G25.71.We found that the NH3cores are in good agreement with the 3.5 mm peak emission,but the NH_(3)is much more extended than the 3.5 mm emission structure.The SO distributions agree well with the 3.5 mm peaks for the evolved star formation stage,but we did not detect any SO emission in the four earliest star formation sources.C^(18)O is a poor tracer in conditions of the cold(■18 K)and dense(■10^(4)cm^(-3))cores,e.g.,the prestellar cores.We also found that the NH_(2)D cores are mainly located in the temperature range of 13.0-20.0 K,and the NH_(2)D lines may be strongly depleted above 20 K.

基于STAR-CCM+仿真软件的双体船水动力性能分析

以某双体船为研究对象,基于STAR-CCM+仿真软件,按网格无关性验证和时间步长无关性验证的要求,对双船体船静水阻力进行数值方法验证,证明数值计算结果的准确性。对不同片体间距、不同片体形态和不同斜向航行角度等工况进行数值计算,分析双体船水动力性能。计算结果表明:在双体船直航时,在片体间距比为0.2、弗劳德数为0.4的工况条件下,与同一航速的其他工况条件相比静水具有明显的骤升现象,且总阻力系数达最大值14.56×10-3;在片体外旋转2°时,与其他旋转角度相比阻力值最小。研究发现,无论是在直航还是斜向航行的情况下,双体船的总阻力系数均呈现先升后降的趋势,说明该船型在处于高速航行状态时具有一定的优越性。

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).

ACE-Star循证护理模型在甲状腺癌患者术后康复护理中的应用效果

目的探讨ACE-Star循证护理模型在甲状腺癌患者术后康复护理中的应用效果。方法采用简单随机抽样法选择2021年1月至2023年4月安徽省阜阳市肿瘤医院收治的100例甲状腺癌患者作为研究对象,采用随机数字表法将其分为对照组和观察组,各50例。对照组实施常规护理模式,观察组实施ACE-Star循证护理模型,观察比较两组术后次日、术后12周的颈部运动度情况。结果术后12周,两组颈部运动度均高于术后次日,且观察组高于对照组(P<0.05)。结论ACE-Star循证护理模型能加快改善甲状腺癌患者术后的颈部运动功能,对改善预后有重要意义。

Formation and Destiny of White Dwarf and Be Star Binaries

The binary systems consisting of a Be star and a white dwarf(Be WDs) are very interesting.They can originate from the binaries composed of a Be star and a subdwarf O or B star(Besd OBs),and they can merge into red giants via luminous red nova or can evolve into double WD potentially detected by the LISA mission.Using the method of population synthesis,we investigate the formation and the destiny of Be WDs,and discuss the effects of the metallicity(Z) and the common envelope evolution parameters.We find that Besd OBs are significant progenitors of Be WDs.About 30%(Z = 0.0001)-50%(Z = 0.02) of Be WDs come from Besd OBs.About 60%(Z = 0.0001)-70%(Z = 0.02) of Be WDs turn into red giants via a merger between a WD and a non-degenerated star.About 30%(Z = 0.0001)-40%(Z = 0.02) of Be WDs evolve into double WDs which are potential gravitational waves of the LISA mission at a frequency band between about 3 × 10^(-3)and 3 × 10^(-2)Hz.The common envelope evolution parameter introduces an uncertainty with a factor of about 1.3 on Be WD populations in our simulations.

Photometric Properties and Stellar Parameters of the Rapidly Rotating Magnetic Early-B Star HD 345439

We first present the multicolor photometry results of the rapidly rotating magnetic star HD 345439 using the Nanshan One-meter Wide-field Telescope.From the photometric observations,we derive a rotational period of 0.7699±0.0014 day.The light curves of HD 345439 are dominated by the double asymmetric S-wave feature that arises from the magnetic clouds.Pulsating behaviors are not observed in Sector 41 of the Transiting Exoplanet Survey Satellite.No evidence is found of the occurrence of centrifugal breakout events neither in the residual flux nor in the systematic variations at the extremum of the light curve.Based on the hypothesis of the Rigidly Rotating Magnetosphere model,we restrict the magnetic obliquity angleβand the rotational inclination angle i so that they satisfy the approximate relationβ+i≈105°.The color excess,extinction,and luminosity are determined to be E_((B-V))=0.745±0.016 mag,A_(V)=2.31±0.05 mag,and log(L/L_(⊙))=3.82±0.1 dex,respectively.Furthermore,we derive the effective temperature as T_(eff)=22±1 kK and the surface gravity as log g=4.00±0.22.The mass M=-7.24_(-1.24)^(+1.75)M_(⊙),radius R=4.44_(-1.93)^(+2.68)R_(⊙),and age τ_(age)=23.62_(-21.97)^(+4.24) Myr are estimated from the Hertzsprung-Russell diagram.