The gravitational binding energy of the Milky Way?

[Researcher X]

Does this even make sense? Just how immense would that be?

 

[mathman]

What do you mean by "gravitational binding energy"?

 

[Researcher X]

That concept doesn't make sense in the case of a galaxy? It's the amount of energy needed to liberate all the particles of a body beyond the ability of gravity to pull them back together.

Basically, how much energy would it take to "blow it up" or pick it apart piece by piece.

 

[mgb_phys]

Gravitational binding energy of a galaxy is simply the energy needed to move each particle (star) in it to infinity - is equivalent of escape velocity.

For each small element of radius simply find the mass inside that radius, then the gravitational potential energy of a star at that radius is just = G m_star m_galaxy /R
You have to then recalculate the remaining mass of the galaxy at each step