The gravitational binding energy of the Milky Way?

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Discussion Overview

The discussion revolves around the concept of gravitational binding energy in the context of the Milky Way galaxy. Participants explore the definition, implications, and calculations related to this energy, considering both theoretical and conceptual aspects.

Discussion Character

  • Exploratory, Technical explanation, Conceptual clarification

Main Points Raised

  • Some participants question the sense of the term "gravitational binding energy" when applied to a galaxy.
  • Others clarify that gravitational binding energy refers to the energy required to overcome gravitational forces and disperse all particles of a galaxy.
  • A participant explains that the gravitational binding energy can be understood as the energy needed to move each star in the galaxy to infinity, relating it to escape velocity.
  • One participant suggests a method for calculating gravitational potential energy for stars at varying radii within the galaxy, emphasizing the need to account for the mass distribution at each step.

Areas of Agreement / Disagreement

Participants express differing views on the applicability and interpretation of gravitational binding energy in the context of galaxies, indicating that multiple competing perspectives remain without consensus.

Contextual Notes

The discussion highlights potential limitations in definitions and assumptions regarding gravitational binding energy, as well as the complexity of calculating it for a galaxy with varying mass distribution.

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Does this even make sense? Just how immense would that be?
 
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What do you mean by "gravitational binding energy"?
 
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.
 
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
 

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