2016年6月10日 · I had always thought that the core of a main-sequence star is defined as the part hot enough for nuclear fusion. Some dictionaries seem to agree with this. However, many books say that protostars and pre-main-sequence stars also have cores, though they are not undergoing hydrogen fusion. So what exactly is the definition of a stellar core?

2023年8月23日 · This is because the core has become electron degenerate, halting the contraction before nuclear fusion is significant and the core just cools thereafter. From this plot you can see that the core temperature of the lowest mass star will be about $10^{6.5}\simeq 3\times 10^6$ K at just above $0.07M_\odot$ .

2024年7月7日 · You find quite a nice summary in the lecture notes by Onno Pols in figure 10.1: There you see the tracks of stars of different masses in the HR diagramme (left) and the track of the very same stars in the core temperature-core density diagrammes with zero-age main sequence denoted by the dotted lines (the dashed in the rhs diagramme show ...

2024年8月4日 · Definition of stellar core? 3. Core collapse supernova vs Neutron Star. 8.

2021年2月12日 · Core temperature: Internally, the core temperatures are dependent on the mass of the star. In our sun, energy is delivered via the proton-proton chain mechanism, which occurs up to about 20 MKelvins, whereas more massive stars can use the Carbon-Nitrogen-Oxygen cycle - which happens from about 15 MKelvins upwards.

The collapse of the stellar core has actually 5 steps, and only the first is well known. 1. exotherm fusion. The first is the fusion of the nuclei until iron/nickel. Also the normal life of the star belongs here. 2. endotherm fusion. While the iron-nickel core is inert on the Wikipedia, it is true only in "normal" circumstances.

Using Hurley's 2000 paper on Single Stellar Evolution, I have graphed the core mass of a star at three stages as a function of metallicity, Z, for a chosen ZAMS mass: at the beginning of the HG (MS), at the end of the Hertzprung-Gap (HG), and at …

Why does fusing iron in a stellar core use more energy than it releases? It doesn't, at least not in the alpha ladder. The alpha ladder starts with the carbon-12 produced by the triple alpha process.

$\begingroup$ yes it is somewhat accurate on main sequence stars, but the sample i used contains stars of various sizes and phases including some extremes, so the formula was accurate for 3 of the values but the rest was quite off: -1,03% 120,39% 45,02% 90,89% 39,04% 232,13% 520,95% 67,30% 98,27% 166,37% 4,37% 3,52% 667,13% 52,90% 51,45% 204,66% 128,23% …

Contrary to common myth, the addition of alpha particles to iron-peak nuclei is exothermic. However, in the nickel/iron core of a massive star, there are no free alpha particles, they must be broken off a nickel/iron nucleus and then fused with another nickel/iron nucleus to …