Toefeline Posted January 5, 2015 Share Posted January 5, 2015 ... a protostar turns into a star when the temperature in the core is about 10 million Kelvin, this I understand. I also understand that a protostar is rotating because of the momentum of the particles falling towards the centre. This rotation is, if I understand it right the reason for the gasses around the star to be blown away. But how is it then possible that different sized stars form? Why is the ignition not always at the same point/mass???Thanks for Your help!Anke Link to comment Share on other sites More sharing options...
michael.h.f.wilkinson Posted January 5, 2015 Share Posted January 5, 2015 Stars do not start out with the same mass, there are different sizes of protostars. The precise temperature and pressure at which the star really ignites may vary, as will the final stable configuration. Heavy stars stabilize at higher internal temperatures and pressures than smaller ones, and consequently burn up their fuel a lot faster. The material blown away when the star ignites is more due to radiation pressure than rotation, as I gather Link to comment Share on other sites More sharing options...
ronin Posted January 5, 2015 Share Posted January 5, 2015 Since stars form from gas clouds I would expect that the temperature of the cloud would be a factor.A cloud at 10K is likely to form smaller stars then one at 8K (K = Kelvin not 1000) The gasses are moving slower at 8K and so I suppose the chance of a greater amount of mass and gravitational attraction before the temperature hits ignition point.The stuff blown off is by radiation pressure from the new star, although the heavier stuff is likely to have started and remainded in orbit around the protostar. I just wouldn't expect a pebble /rock to have been effected by the radiation pressure to a great deal but it would have been influenced by the gravity of the star. Link to comment Share on other sites More sharing options...
michael.h.f.wilkinson Posted January 5, 2015 Share Posted January 5, 2015 I think the size of the stars depends heavily on the initial "clumpiness" rather than the initial temperature. Besides, once a couple of really large stars (like O-B stars) start up, they tend to blow away the remaining gas from the region, so any nearby stars will be deprived of material to grow larger. Link to comment Share on other sites More sharing options...
ollypenrice Posted January 5, 2015 Share Posted January 5, 2015 ... a protostar turns into a star when the temperature in the core is about 10 million Kelvin, this I understand. I also understand that a protostar is rotating because of the angular momentum of the particles falling towards the centre. This rotation is, if I understand it right the reason for the gasses around the star to be blown away. But how is it then possible that different sized stars form? Why is the ignition not always at the same point/mass???Thanks for Your help!AnkeI'm far from being an astrophysicist but I added angular on the basis of my understanding.The part I changed to red I don't understand, or rather this is not my understanding. Could the experts advise?Olly Link to comment Share on other sites More sharing options...
Toefeline Posted January 6, 2015 Author Share Posted January 6, 2015 Thank you for your answers.My question remains ... when a new star forms it is formed in a nebula, and I understand of cause, that if there is more matte in the nebula, a bigger star can form. But still ... particles in the nebula - mostly hydrogen - is attracted by gravitational forces from an area in the gas that has by chance a higher density. The particles "fall" into the core and potential energy turns into kinetic energy, hence the temperature is rising. The "star" starts spinning because of the momentum of the particles "falling" towards the centre (does this by the way mean, that stars turn in different direction, counterclockwise and clockwise???). The temperature raises and the pressure increases ... so far so good. The protostar is visible (if not shield by the nebula) because of thermal radiation. And now, at one point, and that is, when I understand it right, the star ignites, because the temperature in the core and the pressure allows fusion. This happens, when I understand it right, when the critical temp. of about 10 million K is reached. BUT, and here my question, WHY DOES THIS HAPPEN AT DIFFERENT POINTS ??? Do we not need the same temperature and pressure for ignition of all stars? Why can some accumulate a bigger mass before this ignition happens?PLEASE ANYONE OUT THERE UNDERSTANDING THIS PROBLEM AND HAVING SOME THOUGHTS ???? Link to comment Share on other sites More sharing options...
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