# Tag Info

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The resolution is much smaller than the granulation pattern. i.e. The granules are well resolved and are of order 500-1000 km in diameter, not 50 km. The sunspot is of order the diameter of the Earth. Granulation is caused by convective cells rising and falling just below the photosphere. The size of the convective cells is given by some small multiple of ...

2

According to Wikipedia The Chandrasekhar limit is the maximum mass of a stable white dwarf star. The limit was first published by Wilhelm Anderson and E. C. Stoner, and was named after Subrahmanyan Chandrasekhar, the Indian-American astrophysicist who improved upon the accuracy of the calculation in 1930, at the age of 19. White dwarfs with masses greater ...

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Above the Chandrashekhar limit you would obtain a neutron star: https://en.wikipedia.org/wiki/Tolman%E2%80%93Oppenheimer%E2%80%93Volkoff_limit Also see: https://en.wikipedia.org/wiki/Chandrasekhar_limit

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A "collision course" is a very fuzzy concept: if you are "barely going to hit" you are on a collision course but don't need a lot of deflection. However, let's assume for a moment a stationary earth, a meteorite of mass $m$ at distance $D$, heading for earth of radius $R$ with velocity $v$. The equations you need are conservation of angular momentum and ...

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Here are the systems I found: 6: ADS 9731 Beta Tucanae Gamma Velorum Kappa Tauri Mu Sagittarii 7: AR Cassiopeiae Nu Scorpii ... no physical multiple stars of greater multiplicity yet found.

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The first definition of $\mu=GM$ is the standard definition of the SGP. The second one comes from the velocity of a circular orbit. If you have an object in a circular orbit of radius $r$ and velocity $v$ around a body of mass $M$, then the velocity is given by $$v=\sqrt{\frac{GM}{r}}$$ From this you can see that $rv^2=GM$ for circularly orbiting objects. ...

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The sun gets its energy from the pp-chain. The first step is the two protons forming the diproton (Helium-2): $$\,^1_1H+\,^1_1H\to\,^2_2He+\gamma$$ where the $\gamma$ is the photon (of energy about half an MeV). This quickly $\beta^+$-decays into a deuterium by converting a proton into a neutron: $$\,^2_2He\to\,^2_1D+e^++\nu_e$$ where $e^+$ is the ...

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This has a three-part answer. The first part concerns large-scale, quasi-static electric fields. The nice thing about electric fields is that one can always do a simple galilean transformation to a frame where this quasi-static electric field does not exist. So that is the first part (not very satisfactory, but true and practical). The second part ...

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The ejecta of a supernova does indeed move at a fraction of the speed of light (somewhere around the 10% mark). However, it does not remain at this speed forever. As the supernova ejecta expands outwards, it creates a shell of material that is actually gathering up particles in the ambient medium (typical interstellar densities are around 1 particle per ...

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what is the energy of a photon? how much has that energy changed after interacting with the electron? what is the formula for the kinetic ennergy of an electron? if the electron was not moving, and all of the change of the photon energy changed th eelectron's kinetic energy, then what is the speed of the electron? divide the answer from 4. by c.

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Temperature changes using thermodynamic means occur asymptotically. That means cooling through volume expansion is limited. Currently, the lowest temperature reached by humans is 1.0 × 10-10 Kevlins. The star would have to eject gas at near the speed of light to reach that temperature. A super massive black hole would produce an event horizon with lower ...

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I love theoretical physics, I am not capable of the math, but here's a neat comparison. This is one of many proposed solutions to the mean free path of a photon produced in the core of the sun, this one says 4000 years to travel to emission surface...pretty wild drunken walk indeed! This is due to the assumed density of the core and various assumed layers ...

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This is a very late response, but there is no accepted answer as of yet, and none of the answer quite hit the mark. Regarding the magical collision hypothesis, that smacks of being rather non-scientific. Scientists as well as Missourians are wont to say, "Show me!" Other than the fact that Venus's rotation is anomalous, what, exactly, is the evidence for ...

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When observing supernovae, often the bulk of the material is optically thick, so we only see the surface layers. These are moving at some speed $v_\mathrm{surf}$. When modeling supernovae, the very simplistic model everyone loves to use is that of homologous expansion of a uniformly dense (density $\rho$) sphere. That is, velocity of the material increases ...

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Everything in the universe is bathed in the glow of the cosmic microwave background, and this has a temperature of about 2.7K. By this temperature I mean a black body at 2.7K in equilibrium with the CMB would neither heat up nor cool down. So we expect large objects to have a temperature of at least 2.7K because if they were cooler the CMB would heat them ...

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The gravitational binding energy is the sum of the gravitational potential energy, $\Omega$, and the total internal kinetic energy, $U$. If you calculate $\Omega + U$ for a star governed solely by ideal ultra-relativistic electron degeneracy pressure, the net binding energy is zero. This corresponds to the "traditional" Chandrasekhar limit for infinite ...

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The universe now is expanding but its momentum will end and it will stop expanding and a reverse action will occur due to the force of gravitation . It is then when all the universe will shift gear backwards . Thus reversing the motion of the constellations , their stars and their planets . No body knows the speed of the expansion of universe or when it will ...

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