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超新星是某些恒星演化到末期时灾变性的爆发,是宇宙中已知的最猛烈的爆发现象之一。爆发结果或是将恒星物质完全抛散,成为超新星遗迹,或是抛射掉大部分质量,核心遗留下的物质坍缩为中子星或黑洞。在爆炸瞬间以及在爆炸后观测到的现象涉及到多种物理机制,例如中微子和引力波发射、燃烧传播及爆炸核合成、放射性衰变等。 相似文献
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在近期的Nature杂志中有4篇论文提出,某些大质量的恒星在塌缩成黑洞之前仅发射γ射线,而不发射其他物质.天体物理学家们认为,比太阳重8倍以上的恒星在塌缩成黑洞之前,在壮观的超新星爆炸中“死亡”. 相似文献
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恒星结构和演化理论是研究恒星内部的物理过程、结构和恒星如何演化的科学、文章介绍了恒星结构和演化模型的计算方法,恒星在赫罗图中的分布规律,恒星的形成和早期演化特性,质量不同的各类恒星从主序开始的演化进程,恒星演化的晚期阶段的产物;白矮星、超新星和中子星。 相似文献
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根据恒星化学的数学模型,宇宙的第一颗恒星比我们以前想象的要小得多。通过星系演化仿真模拟,被称为星族Ⅲ(Popu-lationⅢ)的第一颗恒星比太阳大100倍。不过这样的恒星,其出生和死亡的过程都短促而激烈,而且不产生钡这样的重元素,这样的重元素能够在星族Ⅱ中发现,星族Ⅱ由星族Ⅲ的灰烬演化形成。美国康涅狄格州纽黑文耶鲁天文学与天体物理学中心(YaleCenterforAstronomyandAstrophysic)的詹森·唐林生(JasonTumlinson)指出,平均质量为太阳质量10~40倍的星族Ⅲ恒星,能够产生今天仍存在的、长寿命的第二代恒星中可观测的化学成分。 相似文献
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一、导致恒星不稳定坍缩的主要物理因素一颗恒星的演化史本质上就是它内部核心区域的热核(燃烧)演化史.一个质量较大的恒星在其演化的一生中将先后经历氢燃烧,氦燃烧,碳燃烧,氖燃烧,氧燃烧以及硅燃烧等热核燃烧阶段.不同质量的恒星经历它所有可能的热核演化之后,通常都要出现较为剧烈的演变.对于质量较低(例如M<8M)的恒星,要经历以前述剧烈热脉冲为特征的AGB星阶段,其核心逐渐收缩为白矮星,而星幔和包层则被向外抛射并膨胀成为行星状星云.大质量恒星(M>8M)则要经历更为剧烈的演变过程,例如像Ⅱ型超新星那样的极其猛烈的爆发. 相似文献
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文章简要叙述了有关大质量恒星形成的理论以及相关观测证据。目前大质量恒星形成的理论主要有两种,即吸积说和并合说.吸积说认为,大质量星可能与小质量星形成于相似的过程;并合说主张大质量星可能是由小质量年轻星碰撞合并而成.解决这两种理论争论的关键在于在大质量星附近能否观测到吸积盘的存在,最新的观测表明大质量星更有可能是通过吸积增加自身的质量,但最终解决这一问题可能还需要更多的观测证据。文章还提出了一些本领域尚未解决的问题,为感兴趣的研究者提供参考。 相似文献
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随着引力波探测以及对中子星质量与半径的高精度测量,中子星作为超新星爆发的剩余产物正吸引着相关领域的高度关注。在中子星的内核部分,诸如超子之类的奇异自由度有可能会出现从而形成超子星。本工作在相对论平均场模型框架下研究由核子与轻子构成的中子星以及包含超子的超子星。采用目前常用的非线性相对论平均场以及密度依赖的相对论平均场参数研究了超子对超子星质量、半径、潮汐形变等性质的影响。最后讨论了介子与超子的耦合常数对超子星性质的影响,发现当矢量介子与超子耦合系数较强时,利用现有的相对论平均场模型参数可以获得大质量的超子星。 相似文献
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We show that self-annihilating weakly interacting massive particle (WIMP) dark matter accreted onto neutron stars may provide a mechanism to seed compact objects with long-lived lumps of strange quark matter, or strangelets, for WIMP masses above a few GeV. This effect may trigger a conversion of most of the star into a strange star. We use an energy estimate for the long-lived strangelet based on the Fermi-gas model combined with the MIT bag model to set a new limit on the possible values of the WIMP mass that can be especially relevant for subdominant species of massive neutralinos. 相似文献
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辐射压是影响大质量恒星结构和演化不可忽视的重要物理因素. 根据辐射压对非同步转动的洛希势函数的影响, 数值计算了洛希瓣的大小和3个拉格朗日点的位置和相应的势函数, 并与同步转动的洛希模型计算的结果做了对比. 结果发现: 辐射压可以整体地减小大质量恒星表面的重力加速度, 而转动离心力能最大减少赤道附近的重力加速度. 辐射压和非同步转动均可以明显地改变洛希瓣的大小和3个拉格朗日点的位置和势函数, 影响双星系统物质交换的时间. 因此, 研究辐射压, 非同步转动等物理因素对大质量双星系统洛希势函数的影响, 对密近双星的演化具有重要意义.
关键词:
恒星结构与演化
转动
辐射压 相似文献
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The equilibria of plasma in a dipolar magnetic field under the gravitational influence of a massive body (a star or black hole) and a self gravitating plasma are considered. Analytical solutions are found that can be useful for understanding the physics of plasma flows in accretion disks and star formation. 相似文献
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《Comptes Rendus Physique》2012,13(1):5-13
Herschel is a spatial submillimetre observatory with spectroscopic and imaging capabilities covering the range from 55 to 671 μm (0.44 to 5.5 THz) partly explored for the first time here. With a primary mirror of 3.5 m, it is presently the largest telescope launched. Its primary targets are the cold dust, the light hydrides, with a special focus on H2O, and a few species of high interest like C+ and O2 in both our Galaxy and other galaxies. Its main focus is on star formation in all its possible aspects including cosmological metal enrichment evolution, statistics on prestellar cores or chemistry of protostar outflow terminal shocks to name only a few. We will describe the telescope and its three instruments, a selection of general results and we will focus on one typical case in greater detail, the observation of water in massive star forming regions. Herschel was launched in May 2009 and should function 3.5 years. 相似文献
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In analogy with spontaneous magnetization of ferromagnets below the Curie temperature, a neutron star (NS), with a compactness above a certain critical value, may undergo spontaneous scalarization and exhibit an interior nontrivial scalar configuration. Consequently, the exterior spacetime is changed, and an external scalar field appears, which subsequently triggers a scalarization of its companion. The dynamical interplay produces a gravitational scalar counterpart of tensor gravitational waves. In this paper, we resort to scalar–tensor theory and demonstrate that the gravitational scalar counterpart from a double neutron star (DNS) and a neutron star–white dwarf (NS-WD) system become massive. We report that (1) a gravitational scalar background field, arising from convergence of external scalar fields, plays the role of gravitational scalar counterpart in scalarized DNS binary, and the appearance of a mass-dimensional constant in a Higgs-like gravitational scalar potential is responsible for a massive gravitational scalar counterpart with a mass of the order of the Planck scale; (2) a dipolar gravitational scalar radiated field, resulting from differing binding energies of NS and WD, plays the role of a gravitational scalar counterpart in scalarized orbital shrinking NS-WDs, which oscillates around a local and scalar-energy-density-dependent minimum of the gravitational scalar potential and obtains a mass of the order of about \(10^{-21}\,{\text {eV/c}}^2\). 相似文献
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A protoneutron star is formed immediately after the gravitational collapse of the core of a massive star. At birth, the hot and high density matter in such a star contains a large number of neutrinos trapped during collapse. Trapped neutrinos generally inhibit the presence of exotic matter — hyperons, a kaon condensate, or quarks. However, as the neutrinos diffuse out in about 10–15 s, the threshold for the appearance of strangeness is reduced; hence, the composition and the structure of the star can change significantly. The effect of exotic, negatively-charged, strangeness-bearing components is always to soften the equation of state, and the possibility exists that the star collapses to a black hole at this time. This could explain why no neutron star has yet been seen in the remnant of supernova SN1987A, even though one certainly existed when neutrinos were detected on Feb. 23, 1987. With new generation neutrino detectors it is feasible to test different theoretical scenarios observationally. 相似文献
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In Newtonian physics, higher temperature leads to higher thermal pressure, which provides stronger support against the gravitational contraction of stars. However, in the temperature range of tens of MeV involved in the evolution of a proto-neutron star or a higher massive neutron star, the effects of temperature are richer. We showed that, for a high temperature neutron star (HTNS) constructed with a realistic equation of state (EOS), the HTNS may expand or contract during cooling, the central density may increase or decrease, the quasi-normal mode oscillation frequencies may increase or decrease, and in particular, (i) independent of the EOS, for a HTNS of a given mass, there exists a maximum temperature \(T_{max}\) that it could ever attend at birth (with the value of \(T_{max}\) different for different EOS), and (ii) for the Hempel EOS and the Shen EOS, there is a range of mass that the HTNS may gravitationally collapse after a period of radiative cooling; however, for the Lattimer–Swesty EOS and Banik EOS, no delayed collapse is possible. Our study, which describes the cooling of HTNSs with simple quasi-stationary TOV sequences, provides an understanding of the effects of the thermal energy/pressure at high temperature, and a demonstration that different EOSs can lead to qualitatively different evolution paths. 相似文献
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We study the hadron-quark phase transition in the interior of neutron stars, and examine the influence of the nuclear equation of state on the phase transition and neutron star properties. The relativistic mean field theory with several parameter sets is used to construct the nuclear equation of state, while the 相似文献