Gravity at the Core of the Sun: How Strong is it?

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Discussion Overview

The discussion revolves around the strength of gravity at the core of the Sun, exploring how it compares to the gravity experienced at the surface. Participants consider the implications of the Sun's varying density and the Shell Theorem in their reasoning.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant notes that gravity at the surface of the Sun is approximately 28g and questions how strong it would be closer to or within the core.
  • Another participant references the Shell Theorem, stating that only the mass inside a sphere contributes to the gravitational force felt at the surface, implying that gravity decreases as one moves closer to the core.
  • In response, a participant challenges the reasoning by asking if the increased density has been considered, suggesting that density affects gravitational calculations.
  • A later reply asserts that the reasoning remains valid despite the increased density, providing an example where within 0.1 of the solar radius, the mass is significantly less than expected under constant density assumptions, leading to a gravitational acceleration of 7.7 times that at the surface.
  • Another participant mentions that gravitational acceleration is stronger than at the surface over most of the Sun's radius, drawing a parallel to similar effects observed on Earth.
  • One participant acknowledges a previous error in their reasoning and expresses regret for deleting an earlier post.

Areas of Agreement / Disagreement

Participants express differing views on how gravity behaves as one approaches the core of the Sun, with some asserting that gravity decreases while others argue that increased density leads to stronger gravitational acceleration. The discussion remains unresolved regarding the exact nature of gravity within the Sun's core.

Contextual Notes

Participants note the importance of considering the Sun's varying density and the implications of the Shell Theorem, but there are unresolved assumptions regarding how these factors interact with gravitational strength.

Kingpin1880
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I'm not 100% sure if this question has been asked/answered or not but I was curious about this subject and I fear I'm not knowledgeable enough to figure out this question for myself. I know that the gravity at the surface of the sun is roughly 28g, but as gravity gets more intense the closer to the centre of mass of the celestial body in question; how strong would gravity be closer to / within the core?
I'll be happy with a rough estimate if it's a bigger question than I think it is; I fell out of love with the study of science after high school, but I still think it a fascinating subject.
(here's hoping I didn't sound pretentious... also; not sure what "prefix" to use so sorry if this question's in the wrong place)
 
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Kingpin1880 said:
I'm not 100% sure if this question has been asked/answered or not but I was curious about this subject and I fear I'm not knowledgeable enough to figure out this question for myself. I know that the gravity at the surface of the sun is roughly 28g, but as gravity gets more intense the closer to the centre of mass of the celestial body in question; how strong would gravity be closer to / within the core?
I'll be happy with a rough estimate if it's a bigger question than I think it is; I fell out of love with the study of science after high school, but I still think it a fascinating subject.
(here's hoping I didn't sound pretentious... also; not sure what "prefix" to use so sorry if this question's in the wrong place)

Edit - This post needs to be prefaced with the fact that it does not take the Sun's varying density into account.

There is a famous result (called the Shell Theorem) which says amongst other things, that only the mass inside a sphere contributes to the force of gravity felt at the surface of that sphere.

So as you move closer to the core of the sun, this imaginary sphere is getting smaller, containing less and less mass and thus the force of gravity is decreasing.

Due to the spherical symmetry of the setup, the attractive forces from outside the sphere, when added up cancel each other exactly.

Another result of the shell theorem is that a spherically symmetric mass behaves as if it were a point mass located at it's center of mass. This is convenient when you are outside the volume of the mass, but is obviously not applicable when inside the object.

https://en.wikipedia.org/wiki/Shell_theorem
 
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BOAS said:
So as you move closer to the core of the sun, this imaginary sphere is getting smaller, containing less and less mass and thus the force of gravity is decreasing.

Did you consider the increased density?
 
BOAS said:
Yes - This does not change my reasoning.
It should. The mass decreases, but radius goes down as well.
As an example, within 0.1 of the solar radius, we have 0.077 of the mass (where a constant density would just give 0.001). That leads to a gravitational acceleration of 0.077/0.12 = 7.7 times the surface gravity.
Data source

I attached a graph (x-axis is radius, y-axis is g relative to g at the surface). Over most of the sun's radius, gravitational acceleration is stronger than at the surface.

The same effect, just weaker, is present in Earth as well. As you go down through the outer mantle, gravitational acceleration increases.
 

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mfb said:
It should. The mass decreases, but radius goes down as well.
As an example, within 0.1 of the solar radius, we have 0.077 of the mass (where a constant density would just give 0.001). That leads to a gravitational acceleration of 0.077/0.12 = 7.7 times the surface gravity.
Data source

I attached a graph (x-axis is radius, y-axis is g relative to g at the surface). Over most of the sun's radius, gravitational acceleration is stronger than at the surface.

The same effect, just weaker, is present in Earth as well. As you go down through the outer mantle, gravitational acceleration increases.

Yes, I realized my error. Sorry for deleting that post - I was hoping I was fast enough.
 

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