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How are stars formed?

  1. Aug 16, 2007 #1
    hi there,
    i plan on becoming an astrophysicist/astronomer/cosmologist and recentley started looking for basic information into astronomy which i should know.
    i was wlndering if i am right about how stars are formed. i will try to put down how i understand:
    in the universe gas clouds could nebulas form and over millions of years gets big enough, approximatley 10billion kilometres wide, to start contracting which will eventually become a star. as the gas clouds contracting the tempreture is very hot and on the average star is 150 000 000 degrees. C. This process also takes long because the most energy and heat is within the centre of the star and takes millions of years to reach the surface where it could be converted to light, etc. energy.
    once the star is large enough and tempreture is high enough the forces cause balance with the gravity causing the gases to contract which then slows and stops the contracting process.
    the tempretures stay high because of mini explosions in the star.

    i know i have many faults in here, so please correct them.

    also holw is gravity formed? and i read somthing about hydrogen turning into helium?
    Thankyou for all help.
  2. jcsd
  3. Aug 16, 2007 #2


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    The first generations of stars were formed from the hydrogen created in the big bang. Something happened to compress the clouds of hydrogen together into galaxies, then smaller regions of the clouds got compressed into stars.
    Many of these early stars were more massive and so reacted faster and used up all their fuel and exploded ito supernova very quickly ( few 100 Myr), this created the higher elements which make up current stars like our sun and the planets.

    To make a star a gas cloud contracts under gravity and the centre heats up, when it is hot enough hydrogen begins to fuse into helium in a nuclear reaction, this creates the energy that makes the sun shine - it also pushes out the rest of the gas in the star which is being pulled into the centre by gravity, this is what makes a star stable. When the fuel runs out and there is nothing to push out the outer parts of the star it collapses in on itself and can form a black hole.

    Gravity isn't formed it happens whenever you have mass.
  4. Aug 16, 2007 #3
    If only we had known how gravity *was* formed.... :p
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