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Therefore, as the body accumulates matter at a given fixed density (in this example, 997 kg/m 3, the density of water), its Schwarzschild radius will increase more quickly than its physical radius. When a body of this density has grown to around 136 million solar masses (1.36 × 10 8 M ☉), its physical radius would be overtaken by its ...
Estimates from an IAU question-and-answer press release from 2006, giving 800 km radius and 0.5 × 10 21 kg mass as cut-offs that normally would be enough for hydrostatic equilibrium, while stating that observation would be needed to determine the status of borderline cases. [50]
Approximate specific stiffness for various materials. No attempt is made to correct for materials whose stiffness varies with their density. Material Young's modulus Density (g/cm 3) Young's modulus per density; specific stiffness (10 6 m 2 s −2) Young's modulus per density squared (10 3 m 5 kg −1 s −2) Young's modulus per density cubed ...
Using the number density as a function of spatial coordinates, the total number of objects N in the entire volume V can be calculated as = (,,), where dV = dx dy dz is a volume element. If each object possesses the same mass m 0 , the total mass m of all the objects in the volume V can be expressed as m = ∭ V m 0 n ( x , y , z ) d V ...
The total mass is divergent, but it is often useful to take the edge of the halo to be the virial radius, R vir, which is related to the "concentration parameter", c, and scale radius via = (Alternatively, one can define a radius at which the average density within this radius is times the critical or mean density of the universe, resulting in ...
A special type of area density is called column density (also columnar mass density or simply column density), denoted ρ A or σ. It is the mass of substance per unit area integrated along a path; [ 1 ] It is obtained integrating volumetric density ρ {\displaystyle \rho } over a column: [ 2 ] σ = ∫ ρ d s . {\displaystyle \sigma =\int \rho ...
For example, if a TNO is incorrectly assumed to have a mass of 3.59 × 10 20 kg based on a radius of 350 km with a density of 2 g/cm 3 but is later discovered to have a radius of only 175 km with a density of 0.5 g/cm 3, its true mass would be only 1.12 × 10 19 kg.
Finally, by the virial theorem, the total kinetic energy is equal to half the gravitational potential energy E G, so if the average nuclei mass is m n, then the average kinetic energy per nucleus satisfies: = = where the temperature T is averaged over the star and C is a factor of order one related to the stellar structure and can be estimated ...