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

In summary, all stars in their life cycle (t) emit energy (E) that follow a bell shape curve. The curve is symmetrical always, but the energy emitted depends on the time?, frequency as a function of time?.
  • #1
kinchit bihani
9
1
TL;DR Summary
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?
 
Astronomy news on Phys.org
  • #2
What is the energy a function of? Time?, frequency as a function of time?
 
  • #3
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?
 
  • #4
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.
 
  • #5
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.
 
  • Like
Likes Vanadium 50
  • #6
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.
 
  • #7
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.
 
  • #8
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.
 
  • #9
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.
 
  • Like
Likes sophiecentaur
  • #10
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.
 
  • Like
Likes sophiecentaur

1. What is the life cycle of a star?

The life cycle of a star begins with the formation of a protostar from a cloud of gas and dust. As the protostar continues to gather mass, it eventually reaches a point where nuclear fusion begins and it becomes a main sequence star. The star will then continue to burn hydrogen for millions or billions of years before running out of fuel and evolving into a red giant, followed by a white dwarf, neutron star, or black hole.

2. How does a star's mass affect its life cycle?

A star's mass plays a crucial role in determining its life cycle. A more massive star will have a shorter lifespan because it burns through its fuel at a faster rate. It will also undergo more dramatic changes, such as becoming a red supergiant before collapsing into a supernova. On the other hand, a lower mass star will have a longer lifespan and will eventually evolve into a white dwarf without going through a supernova phase.

3. What is the bell-shaped energy emission curve of a star?

The bell-shaped energy emission curve of a star is a graph that shows the amount of energy emitted by a star at different wavelengths. It is called a bell curve because it has a peak at the most common wavelength of light emitted by the star, and the curve tapers off on either side. This curve is used to classify stars into different spectral types, such as O, B, A, F, G, K, and M.

4. How does a star's temperature affect its energy emission curve?

A star's temperature is directly related to its energy emission curve. Hotter stars emit more energy at shorter wavelengths, which is why they appear bluer in color. Cooler stars emit more energy at longer wavelengths, making them appear redder. This relationship is known as Wien's law and is used to determine the temperature of a star based on its peak wavelength of emission.

5. Can a star's energy emission curve change over time?

Yes, a star's energy emission curve can change over time as it goes through different stages of its life cycle. For example, a main sequence star will have a different energy emission curve compared to a red giant or a white dwarf. The curve can also be affected by external factors such as interactions with other stars or the presence of a companion star. However, the overall shape of the curve will still follow the bell-shaped pattern.

Similar threads

  • Astronomy and Astrophysics
Replies
3
Views
1K
  • Astronomy and Astrophysics
Replies
11
Views
582
  • Astronomy and Astrophysics
Replies
21
Views
1K
  • Astronomy and Astrophysics
2
Replies
49
Views
2K
Replies
8
Views
2K
  • Astronomy and Astrophysics
Replies
3
Views
2K
Replies
3
Views
371
  • Special and General Relativity
Replies
11
Views
426
  • Astronomy and Astrophysics
Replies
5
Views
3K
Replies
1
Views
955
Back
Top