Neutron stars that can be observed are very hot and typically have a surface temperature of around 600,000 K. The most massive neutron star detected so far, PSR J0952–0607, is estimated to be 2.35 ☐.17 M ☉. It continues collapsing to form a black hole. If the remnant star has a mass exceeding the Tolman–Oppenheimer–Volkoff limit of around two M ☉, the combination of degeneracy pressure and nuclear forces is insufficient to support the neutron star. However, this is not by itself sufficient to hold up an object beyond 0.7 M ☉ and repulsive nuclear forces play a larger role in supporting more massive neutron stars. Neutron stars are partially supported against further collapse by neutron degeneracy pressure, just as white dwarfs are supported against collapse by electron degeneracy pressure. Most of the basic models for these objects imply that they are composed almost entirely of neutrons the electrons and protons present in normal matter combine to produce neutrons at the conditions in a neutron star. Once formed, neutron stars no longer actively generate heat and cool over time however, they may still evolve further through collision or accretion. They result from the supernova explosion of a massive star, combined with gravitational collapse, that compresses the core past white dwarf star density to that of atomic nuclei. Neutron stars have a radius on the order of 10 kilometres (6 mi) and a mass of about 1.4 M ☉. Except for black holes, neutron stars are the smallest and densest currently-known class of stellar objects. I'm not sure what the time scales for this process are.Radiation from the rapidly spinning pulsar PSR B1509-58 makes nearby gas emit X-rays (gold) and illuminates the rest of the nebula, here seen in infrared (blue and red).Ī neutron star is the collapsed core of a massive supergiant star, which had a total mass of between 10 and 25 solar masses ( M ☉), possibly more if the star was especially metal-rich. you treat the electromagnetic field as quantum-mechanical - then the usual non-relativistic electron eigenstates are no longer exact eigenstates of the full relativistic Hamiltonian, and so electrons can undergo spontaneous emission or absorption of photons and change energy levels. I think that what anna v's getting at is that if you include relativistic corrections from QED - i.e. Second of all, I don't understand her claim that superpositions of different energy levels aren't allowed - if this were true, then nothing would ever change with time! \psi_$) energy difference even in the completely non-relativistic limit. It's worth doing this in a bit more detail. However, the relative phase of the two evolves over time, so at some point the $p$ signs will switch over, and the $1s$ blob will be pushed in the other direction. In essence, this is because the $2p$ wavefunction has two lobes with opposite sign, so adding it to the $1s$ blob will tend to shift it towards the positive-sign lobe of the $p$ peanut. If you have a hydrogen atom that is completely isolated from the environment, and which has been prepared in a pure quantum state given by a superposition of the $1s$ and $2p$ states, then yes, the charge density of the electron (defined as the electron charge times the probability density, $e|\psi(\mathbf r)|^2$) will oscillate in time. In this specific instance you are correct.
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