Evolution of Solar Mass Stars
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- Опубліковано 16 чер 2024
- We trace the Sun's Phases of Life and detail what we know about Stellar Evolution. We watch the Sun as it finishes its Main Sequence life, becoming a Red Giant. At the end of this cycle, it will make a Planetary Nebula, and finish with a Degenerate Matter White Dwarf. I also talk about tiny stars: the Red Dwarfs. The Sun will live and die. What is the Sun's fate and the fate of stars with lower mass than the Sun?
The Sun's Phases of Life: en.wikipedia.org/wiki/Sun#Lif...
Stellar Evolution: en.wikipedia.org/wiki/Stellar...
Red Giant: en.wikipedia.org/wiki/Red_giant
White Dwarf: en.wikipedia.org/wiki/White_d...
Degenerate matter: en.wikipedia.org/wiki/Degener...
Planetary Nebula: en.wikipedia.org/wiki/Planeta...
Many Planetary Nebulae: en.wikipedia.org/wiki/List_of...
Asymptotic giant branch: en.wikipedia.org/wiki/Asympto...
Red Dwarf: en.wikipedia.org/wiki/Red_dwarf
0:00 Introduction
1:08 Life Cycles of Stars
3:52 The Evolutionary Cycle of the Sun
5:42 Leaving the Main Sequence
7:10 How will the Sun Evolve?
8:08 Before the Sun was a star...
9:54 The Sun Today
11:38 Evolution of a Sun-like Star
14:54 Hydrogen shell burning
15:12 Hydrogen core exhaustion
17:23 Climbing the Red Giant Branch
21:01 The Helium Flash
21:54 The Triple-Alpha Process
24:14 Horizontal Branch Phase: Helium Fusion
25:23 The Horizontal Branch
26:06 Now the Helium begins to run out...
27:31 Helium core exhaustion
28:41 Asymptotic Giant Branch Phase
30:53 Core-Envelope Separation
32:00 Asymptotie Giant Branch Phase Mass Loss
32:36 Old Age Brings Unsteadiness
33:22 A Nebula Arises
34:33 Planetary Nebula Phase
35:32 White Dwarf
39:33 The Final State
43:04 Small-Mass-Star Hydrogen Core burning - Наука та технологія
Please see the updated version here: ua-cam.com/play/PLyu4Fovbph6d9PJ25kXjmEDSAXQp76Mpl.html
Why does this channel only have 2000 or so subscribers? This channel is a youtube hidden gem. Subbed.
I am just not very active in pushing it around on the social media. It'd be nice for some shares around.
I've been years putting together this information through different sources and you explain it, and much more in a 47 minutes video!!! Amazing. Well, at least what is hard to learn it's hard to forget. Thanks again.
Glad it was helpful!
I really like this!
I’ve always been very interested in astronomy and this quenches my thirst for it. I only just came across your channel a couple days ago and cannot stop watching!
I thank you for taking time to make these.
Please keep it up!
I love these videos. Great use of visuals and graphics, explanations are clear and to the point yet thorough. I plan on watching all of his videos!
Your content and presentations are Top Notch!!
Nice!
(28:55) the voice says "After one hundred thousand years..." but the exhibit shows "one hundred Million years." Which is it?
Thanks for pointing it out, it's the text that's right. I made a mis--speak. I'll fix it when I redo it...
Take a binary system. 1 red dwarf, 1 K, G or F star. The red dwarf is 2-4 AUs from the big star.
Eventually the big star becomes a giant. Would the red dwarf grab enough gas from the expanding giant to change from a red dwarf to a K class star?
A fairly basic question, but when hydrogen shell fusion occurs around the degenerate helium core, will this be CNO rather than proton-proton chain process?
For the Sun, it’ll be the pp chain
@@JasonKendallAstronomer Thanks for that.
Why the core becomes smaller when its mass increases? Is that because it have become more compressed under gravity? Why the core becomes hotter when becoming smaller? Is that because its surface area have decreased, so the pressure on its surface increased?
good questions. Actually, a star's mass doesn't change, but what is uses as fuel does, and what's left as waste after the fuel is used affects its core. Yes, the core gets smaller under gravity pressure because it's not producing as much energy. So, it contracts and heats, just like any other gas. It's not about surface area, it's about the Ideal Gas Law: compress a gas, it gets hotter. However, that compression can become so extreme that it becomes degenerate. (That's where the Helium Flash comes in.). In any event, the main things are that 1) mass does not change, 2) the core converts H to He, using up particles and making it harder for H to find another H to fuse with, 3) H has to move faster to maintain fusion by heating up, 4) heating up comes from the pressure of contraction.
Jason Kendall Thanks. So stars become red giants because when their core became smaller when the nuclear reaction inside it became slower, the temperature and pressure around their core became much greater, so nuclear reaction around the core becomes very fast. Is that right?
yes. exactly. it's a feedback thing.
@@JasonKendallAstronomer Thank you for this explanation and for the fantastic videos you share with us mr. Kendall
What will happen to the outer gas giant planets when the sun becomes a red giant? Will the increased solar wind strip the outer layers off of Jupiter and maybe Saturn? Will Saturn's rings get blown away?
This is all educated guesswork, but here are some main points to consider:
You would have the outward velocity of the solar wind (which forms a "planetary nebula"), combined with the orbital velocity of the planets. The increased flux of ejected gas and plasma would slow down the planets in the prograde direction, of which their orbital height (from the sun) would definitely not be sustained by the outward push (radial-out velocity transfer) of gas. If there is enough to significantly affect the orbits of the inner planets (slowing and capturing the earth and possibly mars), then yes it can probably strip off a lot of the gas giants' atmosphere over ~600 million years. If the sun loses around 1/4 of its mass in this phase, there would be roughly 83,668.005 earth masses worth of "solar wind" to plough through in total. If you knew exactly in what direction, and in what manner, the ejecta would be emitted, then you could say with more certainty how much a certain planetary body would have to swim through over time and how that might affect the orbit.
I don't know about you, but TBH, I'm glad I know the fate of our Earth with more certainty after this introductory video. To know that the solar luminosity is only going to get hotter, and hotter, and brighter from here on out - before the Earth is consumed by hellfire - really puts a pep in my step! And to think that a majority of people might still think otherwise is a travesty.
P.S. If you find the answer to your question, please let me know!
Sir why gravity contracts core further when nuclear fusion starts in outer shell of helium inert core. now there will be a an enough thermal pressure(nuclear fusion in outer shell) which prevent the gravity from collapsing it further
Here we go…
Think about exactly what is contracting. How much there is now versus before. What is it made of. Also think about electron degeneracy pressure. Watch the rest of the series then comment back about why it does contract when you’re done reviewing the material.
@@JasonKendallAstronomer OK sir I will do see your series in order to clear my concept
Think of it as an exercise left for the student. The idea is well understood and is always puzzling for those that first encounter it.
Can I just arbitrarily decide that stars are characterized by fusion, and as such the brown dwarf is actually not a star? Because the brown dwarf really doesn't convince me that it's not just a big hot gas giant that other stuff may orbit around. It would then follow that brown dwarf solar systems be called specifically "brown dwarf systems", with no actual solar activity to justify the descriptor.
Ok, good. On with the lecture, sir.