Are Stars Really Formed by Black Holes?

[superweirdo]

Someone told me stars are formed by black hole, yet, I didn't believe him, are they really?

 

[star.torturer]

no

look up star birth

its from dust + hydrogen in Nebulae + gravity makes lumps which get bigger and bigger causeing the dust to heat up

when they heat up enought they start fission of hydrogen

 

[robphy]

You might get more conversation in the astrophysics forum
https://www.physicsforums.com/forumdisplay.php?f=2

 

[Thrice]

Look it up on wikipedia first.

http://en.wikipedia.org/wiki/Star

 

[chroot]

when they heat up enought they start fission of hydrogen

You mean... fusion.

- Warren

 

[star.torturer]

Yep I do Warren, thanks for pointing this out.
I also knew that it was Fusion, but I didnt proof read the post, Sorry!

 

[superweirdo]

Check this link out, that how he proved it to me.
http://www.space.com/scienceastronomy/mystery_monday_050207.html

 

[star.torturer]

thats interesting, i fully understand where hees coming from. looks like he was kinda right after all

 

[selfAdjoint]

Check this link out, that how he proved it to me.
http://www.space.com/scienceastronomy/mystery_monday_050207.html

Well that isn't the role of a black hole everybody assumed your original post was referring to. Here's a quaote from the site.

New observations portray black holes as Jekyll and Hyde characters. They can be creators as well as destroyers.

The classic view of black holes conjures images of gas and stars and even light being swallowed. That's why they're black. But when black holes feed, they create powerful high-speed jets that race at nearly light-speed into surrounding space.

Like a jolt of electricity breathing life into Frankenstein's monster, a black hole's jets can ignite star formation.

Wil van Breugel and Steve Croft of the Lawrence Livermore National Laboratory studied one of these jets slicing through a puzzling region of intense star formation known as Minkowski's Object. The jet, they say, caused a dense gas cloud to collapse and trigger the star birth.

So the star formation process currently supposed - condensation from a cloud - isn't being challenged. Rather it's proposed that a jet from a black hole triggers that process, at least in some cases.

 

[superweirdo]

But since everytime stars die, they turn into black hole and black hole gives off the stuff needed to make the stars, doesn't it make most of the stars?

 

[Labguy]

But since everytime stars die, they turn into black hole and black hole gives off the stuff needed to make the stars, doesn't it make most of the stars?

Please start at http://www.astronomynotes.com/evolutn/s2.htm" for a decent answer to your questions so far. After reviewing that, you might have some more specific questions.(?) That website has nice pictures too...

 

[vincentm]

But since everytime stars die, they turn into black hole and black hole gives off the stuff needed to make the stars, doesn't it make most of the stars?

Not all stars evolve into black holes. And black holes don't give off anything but radiation in the form of x-rays...

 

[chroot]

Only very massive stars (more than twenty-five times the mass of the Sun) have the potential to become black holes when they die. Most stars do not become black holes, becoming instead only white dwaf stars or being ripped to shreds in a supernova explosion.

- Warren

 

[SpaceTiger]

Only very massive stars (more than twenty-five times the mass of the Sun) have the potential to become black holes when they die. Most stars do not become black holes, becoming instead only white dwaf stars or being ripped to shreds in a supernova explosion.

Well, not entirely ripped to shreds. We expect intermediate mass stars (3 solar masses) to leave behind neutron stars when they die.

 

[superweirdo]

Wait a sec., supermassive stars become normal black hole then what kind of stars make up supermassive black hole. I thought that whenever a star dies, it becomes a black hole and the bigger a star is, the bigger the balck hole is.

 

[star.torturer]

'supermassive black holes' 'exist' in he center of Galaxies, where a collosal mass must have existed to pull together the stars in a galaxy.

 

[superweirdo]

But normal black holes are formed by normal stars right? And supermassive black hole are formed by supermassive stars.

 

[star.torturer]

normal black holes are formed by masive stars

supermassive black holes are formed at the creation of a Galaxy, or maybe a colision of multiple massive stars

 

[chroot]

Supermassive black holes may be of primordial origin, born long before the universe cooled enough to to allow stars to form. On the other hand, they could be simply normal black holes that have absorbed a large amount of matter after formation. The supermassive black holes suspected to exist at the centers of galaxies are almost certainly of primordial origin, and served as the "attractors" that pulled galaxies together in the early universe.

Perhaps one of our resident astronomers can expand more on the topic?

- Warren

 

[franznietzsche]

Wait a sec., supermassive stars become normal black hole then what kind of stars make up supermassive black hole. I thought that whenever a star dies, it becomes a black hole and the bigger a star is, the bigger the balck hole is.

No, only stars with a enough mass so that gravity overcomes the neutron degeneracy pressure will become black holes. We're not entirely sure what that limit is though, because accurately determining the neutron degeneracy pressure is much harder than say determining the electron degeneracy pressure (which is what keeps white dwarfs from collapsing). Its likely that you can't have a neutron star much larger than 3 solar masses (the star that formed the neutron star would of course be much larger). Supermassive black holes would be formed by matter falling into an existing black hole, cause into to grow. You can't have stars much over 100 solar masses as they slimply blast matter off with radiation driven stellar winds when they get to be that big.

 

[Garth]

Supermassive black holes may be of primordial origin, born long before the universe cooled enough to to allow stars to form. On the other hand, they could be simply normal black holes that have absorbed a large amount of matter after formation. The supermassive black holes suspected to exist at the centers of galaxies are almost certainly of primordial origin, and served as the "attractors" that pulled galaxies together in the early universe.

Perhaps one of our resident astronomers can expand more on the topic?

- Warren

It is generally thought that making primordial SMBHs is difficult to explain and those that do exist may have formed by multiple mergers.

Maybe from a swarm of BHs?

Garth

 

[SpaceTiger]

Supermassive black holes may be of primordial origin, born long before the universe cooled enough to to allow stars to form. On the other hand, they could be simply normal black holes that have absorbed a large amount of matter after formation. The supermassive black holes suspected to exist at the centers of galaxies are almost certainly of primordial origin, and served as the "attractors" that pulled galaxies together in the early universe.

Some think black holes could have formed in the early universe, perhaps during a phase transition. This "primordial black hole" hypothesis is actually pretty fringe (though not crank). It is possible that such objects acted as the seeds for supermassive black holes, but most think that SMBHs were seeded by the remnants of Population III (metal-free) stars.

As for the SMBH role in galaxy formation, they may have helped shape the bulges of spiral galaxies (we see correlations between black hole properties and bulge properties), but the primary seeds of galaxy formation were almost certainly the fluctuations put in place by inflation. I suspect that the radiative and kinetic output of AGN (accreting SMBHs) would have been more important in shaping galaxies than the graviational influence of the black holes themselves.