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Asked by WebsA1 to Dave, Ed, Guido, Hugh, Stef on 16 Mar 2015.
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Dave Bond answered on 16 Mar 2015:
Stars form inside relatively dense concentrations of interstellar gas and dust known as molecular clouds. This is the stuff left over from the big bang, for example dust has gravity, so one bit of dust pulls in another bit. The gravity increases a little as there is more mass. Slowly the cloud forms. As gravity gets very strong the cloud in effect implodes and the gravitational forces get very large. Temperature increases as all the atoms are very close at these temperatures, gases become molecular meaning that atoms bind together.
Nuclear fusion occures and a star is made.Nuclear fusion is a nuclear reaction in which two or more atomic nuclei collide at a very high speed and join to form a new type of atomic nucleus. During this process, some of the matter of the fusing nuclei is converted to photons (energy).
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Mariastefania De Vido answered on 16 Mar 2015:
Hi!
Stars are formed from the so-called “interstellar medium”, which is a gas cloud (mostly made of hydrogen molecules (H2)) that is found in the space between stars in a galaxy. At some point, if perturbed by the gravitational field of a nearby star, this cloud can start collapsing on itself . More and more gas and dust progressively gather around the central region, which keeps increasing in mass, causing the cloud to collapse under its own gravitational force. This compression leads to an increase in temperature. After a few million years, a “protostar” is formed. A protostar is a gaseous object which keeps growing in mass by attracting the surrounding gas and collapsing on itself, thus getting hotter and hotter. When the central region of the star reaches a temperature of about 10 millions of degrees, hydrogen atoms start fusing together forming helium through a process called “nuclear fusion”. Fusion releases a huge amount of energy which stops the contraction: a star is formed.
As a result of the fusion process, the star produces a strong particle flux (the so-called “stellar wind”) which sweeps away the remaining gas around it, thus stopping the growing process.Stef
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Ed Rial answered on 16 Mar 2015:
Hi Webs
It looks like this has been answered! The only thing I have to add it’s that the size of stars varies from smaller than our sun, to stars over 1500 times bigger than the Sun! That’s out to beyond the orbit of Jupiter!
Sometimes the collapsing gas cloud will form not one but two stars. These are called binary systems . If Jupiter was just 15 times bigger it would be a star too, and there probably wouldn’t be life on Earth!
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Hugh Harvey answered on 19 Mar 2015:
They go on X factor and get judged by Simon Cowell, and then if they are good enough they make it the TV shows, and then if the public vote for them they become a star.
Oh wait…. wrong kind of star…
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