Chandrasekhar limit....sort of

  • I
  • Thread starter MarkL
  • Start date
In summary, white dwarfs are able to resist gravitational collapse because of electron degeneracy pressure. This pressure prevents electrons from expanding radially through the space between ions. It is not gravity that prevents this, but rather electromagnetism. If electrons were to migrate outwards, the inner part would acquire a positive charge and the outer part a negative charge, creating a strong restoring force that brings back neutrality. There may be slight variations in local net charge with depth, but it is uncertain. Ultimately, the pressure from electrons is enough to support the mass of a star and prevent it from collapsing.
  • #1
MarkL
34
2
From Wikipedia : White dwarfs resist gravitational collapse primarily through electron degeneracy pressure

What prevents electrons from expanding radially through the space between the ions (carbon, say)?
 
Astronomy news on Phys.org
  • #2
Gravity?
 
  • #3
No, electromagnetism I think. If electrons were to migrate outwards the inner part would acquire a positive charge and the outer part a negative charge, which would rapidly become a very strong restoring force bringing back neutrality.

It is possible that you might find that there is a slight variation in local net charge with depth as various different effects push or pull slightly differently on different particles. I don't know for certain. You won't get a pure nucleon core withan electron atmosphere, though.
 
  • Like
Likes ohwilleke and Drakkith
  • #4
bring back...or expand till
 
  • #5
Huh?
 
  • #6
the answer above was: "restoring force bringing back neutrality"
Does this mean,
bring back (to neutrality) = zero electron expansion or prevents electron expansion
or
expand till (neutrality) = electrons expand till force equals fermi pressure = some electron expansion
 
  • #7
MarkL said:
the answer above was: "restoring force bringing back neutrality"
Does this mean,
bring back (to neutrality) = zero electron expansion or prevents electron expansion
or
expand till (neutrality) = electrons expand till force equals fermi pressure = some electron expansion
As my last paragraph said:
Ibix said:
It is possible that you might find that there is a slight variation in local net charge with depth as various different effects push or pull slightly differently on different particles. I don't know for certain.
I'm not sure what question you are asking that isn't answered by that.
 
  • #8
Your last paragraph would never influence an electron with enough pressure to support the mass of a star.
Your first paragraph, however, is spot on and intuitive.
And I'm good...thanks for your response.
 

Related to Chandrasekhar limit....sort of

What is the Chandrasekhar limit?

The Chandrasekhar limit is the maximum mass that a white dwarf star can have before it undergoes a catastrophic collapse into a neutron star or black hole.

Who discovered the Chandrasekhar limit?

The Chandrasekhar limit is named after Indian astrophysicist Subrahmanyan Chandrasekhar, who first proposed the concept in the 1930s.

What is the significance of the Chandrasekhar limit?

The Chandrasekhar limit plays a crucial role in understanding the evolution and fate of stars. It also has implications in fields such as cosmology and nuclear physics.

How is the Chandrasekhar limit calculated?

The Chandrasekhar limit is calculated using a combination of theoretical models and observations of white dwarf stars. It is estimated to be around 1.4 times the mass of the Sun.

Can the Chandrasekhar limit be exceeded?

No, the Chandrasekhar limit is a fundamental physical limit and cannot be exceeded. If a white dwarf star were to exceed this limit, it would lead to a supernova explosion.

Similar threads

Replies
1
Views
2K
  • Astronomy and Astrophysics
Replies
3
Views
1K
  • Astronomy and Astrophysics
3
Replies
77
Views
7K
  • Astronomy and Astrophysics
Replies
2
Views
2K
  • Astronomy and Astrophysics
Replies
1
Views
987
  • Astronomy and Astrophysics
Replies
2
Views
1K
  • Astronomy and Astrophysics
Replies
1
Views
822
  • Astronomy and Astrophysics
2
Replies
49
Views
2K
Replies
5
Views
986
  • Astronomy and Astrophysics
Replies
9
Views
2K
Back
Top