Can nebula theory be Right?

[anise_prakash]

Nebula theory which explains the formation of solar system states that hole of our solar system come from a nebula. Do u think the nebula theory was right?<br /><br />Another theory states that due to gravitation hydrogen in the empty space combine and form the sun and sun forms the planets.<br /><br />Another one states some million years ago a star crosses our sun with a high gravity. It makes our sun to rise up and form the planets.<br /><br />I have lot of confusion.Do anybody give me a clear answer?

 

[qso1]

I think the "hydrogen in the empty space combine and form the sun and sun forms the planets" is the closest to the actual theory of planet formation. The sun is formed from the collecting of gases and dust that become massive enough to ignite and sustain fusion. The remaining dust and gas orbiting the sun coalesces to form planets and other objects.<br /><br />Nebula are usually the remnants of a star that went supernova, the Crab Nebula for example, is believed to be the remains of a star that exploded and was recorded by the Chinese in the year 1054. There are nebula's that are considered to be star birth regions such as the Eagle nebula or the great nebula in Orion. These nebula contain more than enough dust and gas to form stars. <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>

 

[robnissen]

There does not appear to be any way to know where the Sun was born. But, current theory is that it was born with several (numerous?) sister suns and was eventually gravitationally booted out to its current lonely outpost.

 

[kyle_baron]

According to The Night Sky Observers Guide, the sun was most likely born in a nebula which includes stars from Ursa Major (the dipper part of the Big Dipper) and the Hyades, open cluster in Taurus. The exact location is not possible, because all the stars in the birth nebula have left the nursery. <div class="Discussion_UserSignature"> <p><font size="4"><strong></strong></font></p> </div>

 

[doubletruncation]

Hi anise_prakash,<br /><br />I think the first two scenarios, "Nebula theory" and the "gravitational collapse of hydrogen" are essentially the same thing, and this theory is the one that is the most promising. I think part of the confusion may be because there are many different things called "nebulae." In general, a nebula is some diffuse region (as opposed to a compact ball of gas like a star) that is blocking the light from background stars, that is scattering the light from other stars or that is glowing. This is usually the result of some over-density of gas/dust or the presence of some particularly bright star near the gas that's heating it up. The cartoon picture for how stars form is that some overdense region of gas/dust collapses into a star while a disk forms around the star and the planets form in the disk. This collapsing cloud is called the nebula. The collapsing gas/dust is dense enough that it blocks out background stars and scatters light from foreground stars. So you should be able to see nebulae associated with stars that are forming. And in fact that seems to be the case. When you look at areas with the youngest stars they seem to be associated with giant molecular clouds (massive regions of dust/gas). The orion nebula is an example of this. The youngest stars also typically have disks whereas older stars do not, as expected from this theory. As others have mentioned, stars tend to form in groups and we suspect that the sun was no different - there is evidence that there was a large amount of unstable Al26 early in the history of the solar system - this stuff decays away incredibly rapidly and is only produced (so far as we know) in Supernovae, so it seems that there was perhaps a supernova that went off very close to the Sun early in the history of the solar system (and may in fact have induced the collapse of the gas/dust cloud that formed the sun).<br /><br />One of the facts that seems to point strongly toward the "nebula" hypothesis f <div class="Discussion_UserSignature"> </div>