Accretion Induced Collapse

  • Thread starter ibysaiyan
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Hi all,
I recently came across one of the proposed mechanisms by which black hole could be formed as stated above.Can someone please explain me what is it all about? Also what's their relationship with type IA supernovae? I always thought that, a black hole is formed only when a main sequence star of enough mass goes onto become a neutron star which collapses into a supernova leaving a BH...
Thank you!
EDIT:It's like 5 am almost, I better get some sleep.
 

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  • #2
marcus
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Wikipedia probably has stuff about different ways BH can form. Accretion sounds quite reasonable. Maybe you can find a source where that way of getting a BH has been studied.

There must be several ways. two neutron stars could collide and merge and if there was then enough mass. I don't know the precise figure, two or three solar masses.

I could use some sleep too.

One thing you said, about supernovae, I wanted to reply to. Core collapse SN don't always result in BH. In fact the typical end product is a neutron star.

And Type Ia SN may not leave anything behind, where the star that exploded used to be.

Do you know about the Chandrasekhar Limit? about 1.4 solar masses.
Maybe when you are rested you could get some Wikipedia links?

The point is that hydrogen fuses to helium and helium fuses to Carbon and Oxygen and stuff like that, if the star has enough mass to force it to fuse.

But if the star does not have enough mass to force C and N and O to fuse then you wind up with a cooling ball of those elements! And that is a potential BOMB!

C, N, O can fuse into heavier elements, releasing energy. You can have a C-bomb or an O-bomb. All you need is to accrete some more mass onto it until you reach the Chandra collapse threshold.

This can happen in a binary system where the cooling dwarf has a big partner that is blowing off outer layers and some of that extra material falls down and accretes on the dwarf. Until it reaches 1.4 solar and explodes like a C-bomb.

You probably know this already but I'm telling you just in case. Thats why it can turn out there is nothing left of the star that explodes---in that special Type Ia case.

This is a sudden FUSION reaction. It is not like the usual "core collapse" supernova.

In the core collapse type the energy is provided by stuff FALLING towards the center. Gravitational energy. The stuff is mostly iron and iron will not fuse, it is not fuel. So all the available energy is the gravity energy of falling. Part gets blown away and part stays as a remnant.
====================
that's a quick and dirty treatment of common kinds of supernova

but I didn't answer your question. Can a BH form by accretion? Sure, I would think so. Any way you can imagine, to get the necessary mass together.

It is easiest for me to imagine if I think of the mass as neutron matter already.
Then whatever you dump on it will get converted to neutron matter and stay compact. and once it builds up to 2 or 3 solar masses (some threshold like that) it will collapse to hole.

I'd really appreciate it if someone would give us some links to online sources about various ways BH can form including this accretion way. I've had it for the night and don't want to hunt.
 
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Thank you very much.I found your post to be quite informative.I guess now it's all about linking everything together with the little help of the Big-G (google)
If anyone else has more information on this mechanism,your input will be wholeheartedly welcomed.
ibysaiyan
 
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Anyone ?
 
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Oh I have found out a source on these,a good one.
So from what I can make of it, it's related to the conversion of white dwarf into a Neutron star and that there is a binary system.Such that matter is accretes from the companion star until one of the stars reach the Chandrasekhar limit?
http://www.mpa-garching.mpg.de/lectures/ADSEM/WS0910_Wawoczny.pdfGrr [Broken] can Someone please make it more simple to understand.I will read it once more.
 
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