Researchers suggest collapsar accretion disks might be source of heaviest elements

neutron star
Credit: CC0 Public Domain

A trio of researchers at Columbia University is suggesting that collapsar accretion disks might be the major source of the heaviest elements. In their paper published in the journal Nature, Daniel Siegel, Jennifer Barnes and Brian Metzger describe their study of the accretion disks that form as neutron stars collapse into black holes, and what they found.

Space scientists believe that the lightest elements, helium, hydrogen and lithium, originated just after the Big Bang. They also believe that heavier elements such as iron were created in the centers of stars. But such as uranium and gold have remained a mystery—until now, there has been no plausible explanation for their origin. In this new effort, the researchers suggest that such elements were created in accretion disks formed when neutron stars collapse into black holes.

Prior research has suggested that the heaviest elements were created by what is known as the "r-process," in which a chain reaction results in atomic nuclei absorbing neutrons. Astrophysicists had theorized that two neutron stars colliding would likely give way to the conditions necessary for the r-process to occur, creating some of the heaviest elements. Two years ago, the team credited with observing the first gravity waves reported the effects of two neutron stars colliding. Subsequent study of the event showed that it was likely that the r-process had occurred, giving strong credence to the theory. But there was still one problem. The collision of neutron stars is a rare event—too rare to account for the amount of the heaviest elements that exist today. That led the researchers to consider other neutron star activities—such as their gravitational collapse.

Prior research had shown that when neutron stars die, they collapse into . But not all of their material falls into the black hole; some is left behind and forms into an accretion disk. Computer simulations the researchers created showed that conditions in the accretion disks were ripe for the r-process, giving way to creation of the heaviest elements. The team suggests that approximately 80 percent of these elements originate in , and the remainder are created when neutron collide.


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Computer simulation sheds new light on colliding stars

More information: Daniel M. Siegel et al. Collapsars as a major source of r-process elements, Nature (2019). DOI: 10.1038/s41586-019-1136-0
Journal information: Nature

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Citation: Researchers suggest collapsar accretion disks might be source of heaviest elements (2019, May 9) retrieved 21 May 2019 from https://phys.org/news/2019-05-collapsar-accretion-disks-source-heaviest.html
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May 09, 2019
Where's their brain ("smart" scientists and Nature)?
-Earth Chemical composition
Silica……………SiO2……….60.2%
Alumina………...Al2O3….15.2%
Lime…………….CaO………...5.5%
Magnesia……….MgO……..3.1%
iron(II) oxide……FeO……..3.8%
sodium oxide…..Na2O…..3.0%
potassium oxide.K2O…….2.8%
iron(III) oxide…...Fe2O3…2.5%
water…………….H2O……….1.4%
carbon dioxide….CO2…….1.2%
titanium dioxide…TiO2…..0.7%

Sun Photospheric composition (by mass): Hydrogen 73.46%, Helium 24.85%, Oxygen 0.77%, Carbon 0.29%, Iron 0.16%, Neon 0.12% …
A chemical composition of a nebula is quite balanced; a fact which, by the way, follows the general composition of the Universe, which approximately consists of 90 % of hydrogen atoms and almost all of the rest is helium (~10%) with oxygen, carbon, neon, nitrogen and other elements, which, put together, make two atoms per one thousand of them.

May 09, 2019
The extreme release of energy in astrophysical objects is accompanied by outflows, sometimes superluminal. It is important that these phenomena are observed on the scales from stars to galaxies, setting off a unity of explosive processes. But the nature of the central engines remains unclear. In our model all these phenomena have a common nature and the central engines are elastons.
https://www.acade...nization

May 09, 2019
There is unfortunately no open-access version of the paper AFAICT. However, the available abstract makes it clear that relative abundances of r-process elements and supernova elements are not answered by neutron star collisions, by the assumptions made in the paper. Therefore, additional r-process elements (for lurkerz, the "heavy" elements from supernova core collapses are up to and a bit beyond iron, but do not include gold and heavier elements) must be created, and this paper proposes a mechanism in SNe: r-process interactions in the accretion disks formed by the emergence of a black hole. This puts the conjecture of neutron star mergers in tension with their expected abundance, in terms of forming r-process super-heavy elements.

Having been a proponent of the neutron star merger conjecture, I have to admit this is persuasive evidence I was wrong. But not so far wrong in saying SNe core collapses cannot account for the super-heavy elements...
[contd]

May 09, 2019
[contd]
In this paper, it is proposed that r-process accretion can account for 80% of the super-heavy nuclides that form heavy elements, with neutron star mergers accounting for 20%, and that these collapsar accretion disks plus the neutron star mergers are both required to answer the tension in the results. I am still watching with the greatest interest as these tensions are worked out.

May 09, 2019
DS, if I understand your finishing conclusions?
oiu are speculating that there nay be two or more causes for transmutations to heavier elements?

Perhaps even collective series of causation at the NS/AD super-massed collision events?

I agree with that conclusion.
If I misunderstood you? Please let me know.


May 10, 2019
@rr, no you got it right. It says so in the abstract.

May 10, 2019
"A chemical composition of nebulae and stars tell us that the explosions of stars significantly reduce the diversity of elements, existing on a star prior to the explosion.
It is very important to say here that the diversity of a chemical composition of stars is significantly lower in the terms of quantity, ratio and complex atoms, than the ones of the objects that are in the orbit of a star. [3]
The claims that complex elements are created in the explosions of stars and that they arrived to our planet, without having analyzed the chemical composition of all the objects in our system, are unrealistic. Uneven and different chemical compositions of the Sun and its orbiting objects deny such a hypothesis. Relating the existence of complex atoms to the remainders of the stars' explosions is incorrect, because the chemical composition of the remainders, left after a star has exploded, is in a total discrepancy with the composition of objects in our system and because.."

May 10, 2019
".. if that were the case, the chemical composition of all the objects would have been the same, which is disproved by the research and the evidence. [7]
The creation of complex elements is seen in the process of removing the volatile elements of the comets, which is violent and voluminous at the beginning. When a comet has made enough orbits around a star, the quantity of volatile elements in it is reduced and it turns into an asteroid. It should be pointed out that a chemical composition of a comet gets more complex with every turn around the Sun, which is at the end represented in the chemical composition of the asteroid."

May 10, 2019
uhh, ducks? Really? I did try to read your gibberish but I had ro give up when you claimed
" the explosions of stars significantly reduce the diversity of elements, existing on a star prior to the explosion. "

That is completely wrong.
You completely misstate the evolution of simple elements being processed by Nuclear Transmutation IN THE STARS.

The explosion of a star rams the atomic structures of elements together in fission/fusion reactions.

Think of slapping both your hands together, while holding different flavors of jell-o.
Ohh! marketing gold with the new combo!

Building up the complexity of elements, while the star blasting out new heavy metals & wild assortments of combinined elements.

Afterwards, the Space clouds may or may not consist of random quantities of unpredictable variations of old & new matter.

May 10, 2019
You are obviously sleep away (as always) and do not check obvious evidence.
Go back and see again the chemical composition of the Earth, the Sun (stars) and the remains of stars explosions and nebulae (https://www.brita...e/nebula Nebula, astronomy, written by: John S. Mathis).
I can not enlighten superstition, if a person does not want to read.
Honey, illiterate, think of slapping both your hands together, while holding different flavors of jell-o.
Ohh! marketing gold with the new combo!

May 10, 2019
uhhmm, no?

ducks, if you were driving a car down a street with your head stuck in the glove compartment?

I would ask you if you knew who you just ran over!

Because? It would be irrelevant to the situation, to ask what you think you were searching for.

In case you have never considered the idea?
Your big toe on your right foot is different in several features & functions from the index finger on your left hand.

It is helpful to understand those differences when you are attempting to manipulate powertools.

& That knowledge is basically irrelevant when you scratch your butt as it itches,

May 11, 2019
You can clearly see, from your comments, that's science for you a foreign body.
Dear, the topic is something else.
You do not like the evidence and now you cackle about nonsense.

May 11, 2019
duck, you're plagiarizing of other people's work?
To which you did not contribute.

No more proves you are knowledgeable or even understanding of the articles you are commenting upon.

Than a dog barking at the squirrels in a tree.

May 11, 2019
Serious folks wrote the articles here. They are about accretion disks. Nowhere in the spitball fight between the two above individuals is anything concerning the article. Not to mention the near impossibility for we humans to even get near such a disk in such a proximity to the most dangerous objects in the universe without getting trapped by such black holes. Those 'accretion' disks' would be maybe for a short time outside the Schwartzwald radii, but such would be spiraling inward toward that BH in short order. So any 'mining' attempt would be suicide unless done by a well equipped expedition by an advanced society. Better to observe and manufacture the materials 'in micro'.

May 11, 2019
Author Weitter Duckss
Independent Researcher, Zadar, Croatia

The last three articles (the fourth was sent yesterday for publication https://www.svemi...i.com/).

http://www.scienc...80603.13 more than 9,000 visits
Paper Number: 3011059
Paper Title: How are the spiral and other types of galaxies formed?
has been published in American Journal of Astronomy and Astrophysics.

https://www.ijsci...1908.pdf "Effects of Rotation Araund the Axis on the Stars, Galaxy and Rotation of Universe" International Journal of Sciences

https://doi.org/1...IAJ.2055 "Why do Hydrogen and Helium Migrate" the Intellectual Archive

Who is dog that barking at the squirrels in a tree? You?

May 12, 2019
Oziris
Serious folks wrote fairy tales and lies in the articles here.

Now we have their lawyer without cover.
"Go back and see again the chemical composition of the Earth, the Sun (stars) and the remains of stars explosions and nebulae (https://www.brita...e/nebula Nebula, astronomy, written by: John S. Mathis).
I can not enlighten superstition, if a person does not want to read."

If you have a black hole in your head this is not our problem. We just attach evidence that is not disputable to the whole world except you and the authors of the article (and a handful of similar "smart scientists").

May 12, 2019
Maybe if your link actually worked.


May 12, 2019
Which has to do with what, now? Doesn't look like collapsars or accretion disks to me.

May 12, 2019
Da Schneib you lost me when you said you needed to "understand advanced math to understand climate change". :/

May 12, 2019
Which has to do with what, now? Doesn't look like collapsars or accretion disks to me.


We discuss the chemical composition. The authors argue that the chemical composition is opposed to official evidence.
For authors country received all the complex elements of something that does not have these elements. At the same time, no body in our system has the same (or similar) chemical composition. The Earth is superior in the richness of complex elements opposite the stars (quantity and diversity).
The relation is the same as, that 400 poor people (the total number remains (super ..) nevae in the Milky Way) food 200-400 billion rich…

May 12, 2019
Hmmmm, last time I checked the r-process is a nuclear reaction, not a chemical one.

Maybe you forgot.

May 12, 2019
Old_C, I wasn't aware this was another climate change thread. Looked more like an astrophysics thread to me.

Maybe you forgot.

May 13, 2019
The claims that there is a radioactive disintegration need to be dismissed as incredible; more than half a million of people live only around Vesuvius in Italy and they are not irradiated. Lava can be hot, but never radioactive (low radiation that exist in the lava is considered that they are not harmful to people and life). The conduct of matter in blast furnaces for melting iron is known; therefore, it is also known that hot mass is dislocating, which means that radioactive elements should be equally present in lava now and 4,5 billion of years earlier – but, they are not "(Ultramafic (picritic): SiO2 <45%, Fe-Mg> 8% and up to 32% MgO, temperature up to 1500°C))".
The mass which creates pressure and the effects of the gravitational forces of Sun are responsible for the melted core. That is the reason why Venus is more warm than Earth and has more active volcanoes, although it is smaller than Earth. Therefore, there are convincing and verifiable evidence for the objects to shine. ..

May 13, 2019
You mean other than all those people at Chernobyl?

And what's heat got to do with it?

May 13, 2019
Chernobyl is a proof that there is no fission and fusion in the stars and bodies with the molten core.
"Light appears on the place of collision between radiation waves and particles. If there is no radiation, or if it is minimal, matter is very cold. If there is no visible matter, space warms up (80 to 180°K), just as visible matter. An important difference is that space does not produce light in collisions with radiation, no matter the intensity or sort of radiation.
Warmth and light are produced only by visible matter. The light of Sun disappears immediately after leaving the atmosphere of Sun or with the disappearance of visible matter. Temperature drastically falls after leaving the atmosphere, but it does not disappear immediately (80 to 100°K) – it gradually diminishes with the increase of distance through space. ..
Space equals complete dark. Light appears only on objects (nebulae, planets, etc ). If there is no visible matter, there is no light. ..

May 13, 2019
@wduckss

Break the pills in half or maybe double up one or the other.

May 13, 2019
@hat1208
Maybe you're right. It is time to conclude this topic.

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