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A Star's Life, (Full Explanation)

  1. Mar 11, 2009 #1
    Can someone explain all the known paths a star can take from its birth to its death?
    This is what I know so far. Please correct me or add things where they need to be in the list

    1) Hydrogen gas, clumps together by gravity.

    2) Hydrogen atoms bump against each other and these collisions cause a rise in temperature.

    3) The temperature of the gas gets very high. Also the pressure gets high too from gravity
    a) Electrons are excited by the increase in pressure and temperature, collisions with lesser energtic electrons causes a change in energy, thus light is emitted.
    (Need explanation) for other reasons why light is emitted.
    b) A proto-star is created. A star is in the development stage.
    c) If a star is not born, it turns into a brown dwarf.

    4) A critical temperature and pressure needs to be reached. (Need explanation)
    a) (Need explanation) Why does Hydrogen nuclei fuse exactly? I will provide a reason of what I think in part 4b.
    b) Fusion occurs when the force of gravity overcomes the electromagnetic force of the nuclei. Then the two nuclei come close enough for the strong force to take over.
    Somehow the mass of the the two nuclei is reduced, the change in mass = energy output. (Need explanation)

    5) Fusion occurs between two nuclei, energy is released, other nuclei start to fuse. Chain
    reaction occurs. A star is born.

    6) Depending on the initial amount of hydrogen gas, the star's life will be different.
    a) If the star's mass is low, then it will live for billions or maybe trillions of years. (Need explanation)
    b) If the star's mass is high, then it will live for millions of years. (Need explanation)

    6a) This star will fuse hydrogen nuclei an neutrons into a helium atom. (Need explanation) for where neutrons come from.
    I) Fusion rate decreases over time, less and less hydrogen nuclei. Graivty increases.
    II) The force of gravity exceeds the outwards force caused by fusion energy. Net force is inwards. The inwards force increaes at a certain rate.
    III) As the inwards force increases the outer most layer of helium and if there is some hydrogen gas expand. Star turns into a red giant.
    IV) Eventually hydrogen and helium gas that were far enough away from the center of the star escape. Class 1 Supernova.
    V) The rest of gas, mainly helium now are subjected to a strong gravatational force.
    VI) (Need explanation) Somehow less massive stars can't fuse helium.
    VII) Star somehow turns into a white dwarf, white dwarfs don't collapse because of electron repulsion. (Need explanation)
    VIII) Something happens and the white dwarf ceases to exit anymore. (Need explanation)

    6b) This star will fuse hydrogen nuclei and neutrons into a helium atom. This star is massive so, it will be able to fuse helium and more.
    I) The star's internal structure is analogous to an onion because of different elements with different masses.
    II) The star fuses more and more nuclei, and different elements are made within the star. The most massive elements are in the center, iron and the lightest element are near the surface, hydrogen.
    III) Iron nuclei don't fuse because it is not energy benefitial (Need explanation).
    IV) The iron core becomes non fusable and more and more iron is created from the fusion of the other elements.
    V) The iron core collapses and becomes very dense, because of gravity? (Need explanation)
    VI) The other layers of elements are released from the sudden collapes of the iron core. Class 2 Supernova.
    VIII) The iron core becomes compressed, and the electrons that are around somehow fuse with the protons in the iron.(Need explanation) The star becomes a neutron star.
    IX) A neutron star somehow becomes a blackhole, (Need explanation)

    7) So in the end, you end up with white dwarfs, neutron stars, and black holes. (Need explanation) to what happends to the white dwarf, neutron star or black hole.
    a) White dwarfs somehow cease to exist
    b) neutron stars somehow disappear
    c) Black holes decay from Hawking radiation

    8) Stars may have partners, binary stars. There are different possibilites.
    a) If two neutron stars orbit each other, they create gravatiational feilds. Light is emitted, and if light is directed towards earth, we see this light as pulses, we call this pulsars. Once the neutron stars collide, they explode, another super nova?
    b) If two white dwarfs orbit each other, they create ... (Need explanation)
    c) If a white dwarf orbits a neutron star, the white dwarf would collide into the neutron star because it is more massive.... another super nova?
    d) When a white dwarf or neutron star collides into other stars, depending on the masses of the celestrial bodies, a super nova occurs...?
    e) What other possibilites are out there?

    9) Explosions from stars release differnt elements, and during a supernova, higer elements are created (Need explanation)

    10) This concludes the life of a star.
  2. jcsd
  3. Mar 11, 2009 #2
    I might suggest breaking up your questions into separate topics. You are asking approximately 15 questions about stellar life. The proper way to answer your question is to write you a book on the subject. Break up the questions, and it will be easier to solve your riddles.

  4. Mar 11, 2009 #3
    I am not asking one person to answer my long set of questions. I was expecting one person to tackle one question at a time. And I was expecting different people to answer different parts of my questions. Now I realize, since the post is so long, I think people just don't want to read it.
  5. Mar 11, 2009 #4


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    Staff Emeritus
    Science Advisor
    Gold Member

    You should look into the Hertzsprung-Russell diagram, which shows the entire gamut of possible stars. As stars age, they move from place to place on the diagram. As a result, you can draw a curve, a "track," on the H-R diagram representing any specific star's life.

    Many different tracks have been computed and can be visualized on the diagram.

    The number of possible tracks is technically infinite -- even very small variations in initial mass can result in significantly different tracks on the H-R diagram. In practice, though, stars generally move along a relatively small number of well-understood categories of tracks, and that's probably the answer you're looking for. The exact number of such categories is not known, because stellar evolution is not completely understood at this time.


    - Warren
  6. Mar 12, 2009 #5
    Thanks alot. Sorry for the long post.
  7. Mar 12, 2009 #6
    Last edited by a moderator: May 4, 2017
  8. Mar 12, 2009 #7


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    Staff: Mentor

    One should be able to find a text in astronomy and astrophysics, which discusses the evolution of stars, e.g. Introduction to Modern Astrophysics, An (2nd Edition) by Bradley W. Carroll and Dale A. Ostlie, or more specifically An Introduction to Modern Stellar Astrophysics by Bradley W. Carroll and Dale A. Ostlie.

    There are many texts, which are devoted to stellar evolution (type "Stellar Evolution",books into Google or go to any bookseller website and search on "Stellar Evolution")

    Principles of stellar evolution and nucleosynthesis By Donald D. Clayton

    There are class notes on-line - http://cass.ucsd.edu/public/tutorial/StevI.html


  9. Mar 12, 2009 #8
    Even if a person did tackle this in one shot, it will be far too much explanation where you could just easily read it on a book dealing with the topic. People are going to read the post, just they aren't going to tackle one question at a time. There are different types of of a stars, not just one type of star, which have their their unique cycle of life and characteristics.
  10. Mar 12, 2009 #9
    Thanks a lot Everyone!!!
  11. Mar 13, 2009 #10
    I agree with these replies. It is unfortunate that the explanations to your post can easily span more than an entire course worth of material. Books are fantastic places to get this information. However, like other people here have suggested, you should focus on one question at a time. It will help keep you focused.

    On another note, I am a huge fan of stellar structure and evolution.
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