A question about black holes

johnjohnson81 · Jul 10, 2004

Are any heaver elements created in the accreation disk around a black hole?

zavvy · Jul 10, 2004

Nobody knows for certain. It's all theory and speculation...

johnjohnson81 · Jul 11, 2004

The matter that is in the acreation has not entered the black hole yet so it can escape I think.I was wondering about the early universe and the effects of feeding blaxk holes.And i thought i read one time that a super massive feeding black hole acts like a fountin and shoots stuff through the galaxy

rogers_buck · Jul 11, 2004

The x-ray spectra might provide an answer were it possible to resolve absorption bands.

rogers_buck · Jul 11, 2004

I don't see what mechansim could exist in the disk to generate heavier elements. Perhaps fleetingly when two nuclei collide but there would be no true merging. What mechanism are you thinking about for the particle fountain other than newtonian effects? I don't believe Hawking radiation consists of any baryons.

omega_man · Jul 12, 2004

Although the matter that is in the accretion disc has not entered the black hole, it will, unless you can think of a mechanism that would propel it away at near c.

alokmohan · Jul 12, 2004

A neuclear fission like thing may occur.Nobody knows.

omega_man · Jul 12, 2004

Nuclear fission would produce lighter elements. AFAIK, nuclear fusion requires a containment (as in the gravitational compression of the Sun), whereas an accretion disc would allow dispersion.

Saiph · Jul 12, 2004

I think it is highly unlikely. 1) For heavier elements to be created,by this I'm assuming anything other than hydrogen and helium, you need two nuclei to hit hard. 2) The speeds in accretion disk are sufficient, however most nuclei are heading in the same direction, so the relative speeds are usually small. Thus you can't factor this source of velocity into the system. 3) The Tempreature is quite high, giving a high random motion...this is key. At least, near the inner edge of the accretion disk. 4) The density is not high however. So, while it is possible for two nuclei to collide and fuse, it is hiighly unlikely to do so due to the low density. So we arent' going to see much (basically none), and it's going to be obscured by the presence of heavier elements with the normal stellar source. <div class="Discussion_UserSignature"> --------------------SaiphMOD@gmail.com -------------------"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- The Tenth Doctor, "Blink" </div>

spacechump · Jul 12, 2004

I used to be a regular here, before the reset. Can you guess which one? I'll guess...steve?

redvoodoo · Jul 12, 2004

"I used to be a regular here, before the reset. Can you guess which one?" I'm guessing ricimer.

Saiph · Jul 12, 2004

You got it red. Time to change the sig, well, I'll leave it for a few more days. <div class="Discussion_UserSignature"> --------------------SaiphMOD@gmail.com -------------------"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- The Tenth Doctor, "Blink" </div>

rogers_buck · Jul 12, 2004

If the system did not satisfy the virial theorem, it would not be stable and would loose mass. A different (quantum) virial theorem precludes the nuclei from fusing for analagous reasons. No fusion, but why not mass ejection if the KE is too high?

spacechump · Jul 12, 2004

Ah ricimer! Welcome back!

Saiph · Jul 12, 2004

The system isn't "stable" it constantly feeds into the BH. I don't think it precludes fusion. Please, go into it more, that way I and others can get a better look at your insight. There is ejection of materials, via polar jets. <div class="Discussion_UserSignature"> --------------------SaiphMOD@gmail.com -------------------"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- The Tenth Doctor, "Blink" </div>

rogers_buck · Jul 12, 2004

Actually, I claim little insight. I have seen the pictures of polar mass ejection and never thought about it much. But if the KE of the system exceeds twice the gravitational PE of the system then the system would be unstable. Chucking things out at the poles, I don't know and would be interested in reading about that. I will hazard the guess that there is some dynamo at play, perhaps as a result of charged ions whipping around at relativistic velocities as they go down the tubes. Just a guess. For nucleons to merge the nuclei must be under pressure. Nuclei can collide and merge breifly (reproducing x-ray specra of a heavier element) but they have to overcome the same KE vs. PE requirement to remain stable. Ergo the need for high pressures.

Saiph · Jul 12, 2004

? The fusion reaction isn't stable, it's spurious and spontaneous. Also nearly non-existent. All you need is two particles to collide hard enough, the resulting nuclei is just as stable as if it formed in a stellar core. Now, the rate of reaction will go up with pressure, but that's because you'll have more particles nearby, and the energy released will be more likely to fuel the next collision, instead of escaping scot free. I'll tack the polar jet explaination onto the Preliminary BH FAQ request. <div class="Discussion_UserSignature"> --------------------SaiphMOD@gmail.com -------------------"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- The Tenth Doctor, "Blink" </div>

Saiph · Jul 12, 2004

considering how short of a life massive stars live, I'd actually argue we're further down the generation list than 3rd. <div class="Discussion_UserSignature"> --------------------SaiphMOD@gmail.com -------------------"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- The Tenth Doctor, "Blink" </div>

petepan · Jul 12, 2004

steve said I'm still trying to find which constellation your handle comes from www.astro.uiuc.edu/~kaler/sow/saiph.html SAIPH (Kappa Orionis). Orion's magnificence stems from the striking figure that appears like the outline of a person looking back at you. But he -- she to the Arabs -- would be little without the brilliance of his stars. Topping the list in beauty are Rigel and Betelgeuse and the three stars of the belt. They so dazzle that we pay less heed to Orion's other bright stars, Bellatrix (which ranks number 3) and Saiph (number 6, and brighter than Mintaka at the right-hand end of the Belt). As bright as it is, mid-second magnitude (2.06), Saiph scored only Bayer's Kappa designation. Even its name is borrowed. "Saiph" comes from a longer Arabic phrase that means the "sword of the giant," and originally referred to Orion's famed Sword that drops below his belt and contains the great Orion Nebula. The name was then erroneously transferred to the lower left star of Orion's seven-star figure, and it stuck. One of the hotter stars in the constellation, Saiph, with a temperature of 26,000 Kelvin (hot class B), shines with a sparkling blue-white light. At a distance of 720 light years, it pours its radiation into space at a rate 57,500 times greater than does the Sun. Though at about the same distance as Rigel, Saiph looks fainter because its much higher temperature causes the star to radiate much of its light in the invisible ultraviolet. From its spectrum -- its array of colors -- Saiph is classed as a "bright supergiant," implying that it is well along in its evolution, having entirely stopped hydrogen fusion. Confusingly, however, its luminosity and temperature place it close to the region of hydrogen-fusion stability, as if it were just in the process of developing into a supergiant. Whether true supergiant or not, it is st

Saiph · Jul 13, 2004

ditto <div class="Discussion_UserSignature"> --------------------SaiphMOD@gmail.com -------------------"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- The Tenth Doctor, "Blink" </div>

Leovinus · Jul 13, 2004

All those who have seen this happen didn't live to tell the tale. <div class="Discussion_UserSignature"> </div>

petepan · Jul 13, 2004

No worries guys, I had 5 minutes to kill so did a quick google, hey it was fun too, i learnt something!! Cheers Peter

A question about black holes

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