The life cycle of a star and the bell shaped energy emission curve

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Discussion Overview

The discussion revolves around the energy emission patterns of stars throughout their life cycles, specifically questioning whether these emissions follow a bell-shaped curve. Participants explore the implications of this shape in relation to stellar evolution, the Hertzsprung-Russell Diagram, and broader cosmic phenomena.

Discussion Character

  • Debate/contested
  • Exploratory
  • Conceptual clarification
  • Technical explanation

Main Points Raised

  • Some participants question whether all stars emit energy that follows a bell-shaped curve, suggesting that this may not be universally applicable.
  • There is a proposal that while individual stars may not exhibit a perfect bell shape, a large dataset of stars could approximate a normal distribution.
  • One participant mentions the Hertzsprung-Russell Diagram as a useful tool for understanding stellar evolution, noting that it does not represent a bell shape.
  • Another participant argues that the concept of a bell-shaped curve could be extended to other cosmic phenomena, such as the life cycles of black holes and the expansion of the universe, although this idea is met with skepticism.
  • Concerns are raised about the validity of personal theories and the lack of empirical evidence supporting the claims made about bell-shaped curves in stellar luminosity profiles.
  • Some participants express frustration with the vagueness of the arguments presented, questioning the reasoning behind the proposed connections to broader cosmic trends.

Areas of Agreement / Disagreement

Participants do not reach a consensus on whether the energy emissions of stars follow a bell-shaped curve. There are competing views regarding the applicability of this concept to individual stars versus larger datasets, as well as its relevance to other cosmic phenomena.

Contextual Notes

Some participants highlight the need for clearer definitions and empirical evidence when discussing the shape of energy emission curves. There are unresolved questions regarding the exact nature of a "bell shape" and its implications for stellar luminosity profiles.

Who May Find This Useful

This discussion may be of interest to those studying stellar evolution, cosmology, or the mathematical modeling of physical phenomena in astrophysics.

kinchit bihani
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TL;DR
Do all stars in their life cycle (t) emit energy (E) that follow a bell shape curve?
Do all stars in their life cycle (t) emit energy (E) that follow a bell shape curve? If yes, is the curve symmetrical always? How is this related to nuclear and thermal time scale?
 
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What is the energy a function of? Time?, frequency as a function of time?
 
kinchit bihani said:
Do all stars in their life cycle (t) emit energy (E) that follow a bell shape curve?
No! Where did you get the idea that they do?
 
Energy generated (y) by a star plotted over its lifetime (x).
My basic understanding comes from looking at the process of stellar evolution. How their luminosity increases with time before they run out of fuel.
 
Why don't you try making such a plot for a star like the sun? The http://mesa.sourceforge.net/index.html has code for stellar evolution. The "Evolve a 1 Msun star" link under "code capabilities" has the luminosity of the sun throughout it's life calculated. It does increase at the beginning of its life and decrease at the end, but there are many bumps and wiggles along the way. If this is what you call "bell shaped" then maybe your statement is correct.
 
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Given that every star starts and ends at L = 0 and has L > 0 in between there is a certain amount of bell-shapedness. But I don't think this triviality is what the OP has in mind.
 
I find the Hertzprung-Russel Diagram useful for understanding stellar evolution and measurements that determine where a star appears on the diagram as it ages. Not a bell shape yet quite beautiful:

1586048554790.png


Some common stars in the Milky Way galaxy charted on an H-R diagram. Note Sol at 1 solar luminosity and above G2 with other yellow stars.
 
Thank you all for your replies.
It is possible that the shape of the curve for one star is not an exact bell-shape. However, if the same curve is plotted for a large data set of stars, it might approach a normal distribution.

There is a broader point that I have in mind. Is the bell-shaped curve applicable more widely in the universe? In the birth and death of black holes (which grow and then shrink), galaxies or other celestial objects and also growth of human bodies too?

If that is the case, the universe which is the sum total of all its observable parts, should follow the bell-shaped curve too. In its current expansion phase the universe will continue till it reaches its peak and then began to de-accelerate. And since the rate of the expansion phase is not linear (in a bell shape), it can explain why the rate of the expansion of the universe (Hubble constant) should not be constant too.
 
kinchit bihani said:
It is possible that the shape of the curve for one star is not an exact bell-shape. However, if the same curve is plotted for a large data set of stars, it might approach a normal distribution.
No. Why would it? There is no reason to expect it to.

kinchit bihani said:
If that is the case, the universe which is the sum total of all its observable parts, should follow the bell-shaped curve too. In its current expansion phase the universe will continue till it reaches its peak and then began to de-accelerate. And since the rate of the expansion phase is not linear (in a bell shape), it can explain why the rate of the expansion of the universe (Hubble constant) should not be constant too.
To be perfectly frank, this just sounds like word salad to me. There is no tangible reasoning here. This is starting to sound like a personal theory to me (and note that personal theories are not allowed here).

Current cosmological models have no issues in predicting a changing Hubble rate. The Hubble rate is constant only if the Universe accelerates.
 
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kinchit bihani said:
It is possible that the shape of the curve for one star is not an exact bell-shape
What would the exact bell shape be? You've already been asked that question but you seem to have ignored it. Are you just invoking the Central Limit Theorem?
 
  • #11
I agree with Orodruin that this sounds like a personal theory.

Since it apparently makes a prediction of stellar luminosity profiles, the fact that you immediately declared that it was still OK with ensembles of profiles with no evidence means you aren't doing science with this personal theory.

And no, that's not bell-curved wither, except in the trivial instance that it starts and ends up at zero and is non-zero in the middle.
 
  • #12
Since the thread is devolving into personal speculation, it’s best to close it for now.

Thank you all for participating here.
 
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