We are all stardust...

[barbos]

9 billion years is a long time. A lot of stuff could happen, and don't forget once it happens it's get blown in all directions.

We're still on the same star for nearly 5 billion years now, and there's 5 billion more to go before it self destructs. So, 9 billion y.o. doesn't seem all that long to me when it comes to stellar evolution timescales.

Massive stars live very short time before they die and explode - 10-20million years

 

[Shadowy Man]

This seems wrong in places. For example, solely identifying the origin of Uranium with "merging neutron stars" is clearly incorrect. There are probably other errors here as well; I haven't examined it fully.

What do you believe is the (other) significant mechanism that generated the Uranium found on Earth, and why?

Supernovae, as mentioned in Anna Frebel's talk that you actually linked to on page 1 of this thread.

 

[barbos]

What do you believe is the (other) significant mechanism that generated the Uranium found on Earth, and why?

Supernovae, as mentioned in Anna Frebel's talk that you actually linked to on page 1 of this thread.

Yes, merging neutron stars seems unnecessary.

 

[repoman]

Can't wait until the more gravitational wave detectors come online with enough sensitivity and neutron star collisions are triangulated to a small section of the sky.

 

[Shadowy Man]

Supernovae, as mentioned in Anna Frebel's talk that you actually linked to on page 1 of this thread.

Yes, merging neutron stars seems unnecessary.

And my guess (without running the numbers) is that they wouldn't be able to account for the abundance of Uranium.

 

[fast]

We are not stardust.

 

[Kharakov]

A majority of my body's atoms are actually big bang hydrogen, not second or 3rd generation starpoop. I think poop is offended.

 

[Loren Pechtel]

How does merging neutron stars make elements here on Earth?

1) How does anything emerge? Isn't the result inevitably a black hole?

2) Even if it doesn't go black hole how does much escape?

 

[bilby]

How does merging neutron stars make elements here on Earth?

1) How does anything emerge? Isn't the result inevitably a black hole?

2) Even if it doesn't go black hole how does much escape?

You don't need a very significant percentage of a neutron star to produce enough mass for a few lousy planets. Even big planets like Jupiter are piddling amounts of stuff compared to even fairly boring stars like the Sun.

The Earth (and all the rest of the 'metals' in the Solar System) is a tiny scrap of barely significant slag. The question in my mind is the opposite of yours - even if a black hole is formed by merging of two neutron stars, how could this happen so cleanly as to avoid ejecting at least planetary mass quantities of debris? One part in a million of ejecta would be far more than enough - and a big energetic event is going to have quite a bit of stuff flying away from it at significant fractions of c.

 

[T.G.G. Moogly]

How does merging neutron stars make elements here on Earth?

1) How does anything emerge? Isn't the result inevitably a black hole?

2) Even if it doesn't go black hole how does much escape?

The crab nebula is a supernova explosion. When stars go supernova the outer shell of material gets ejected. Rocky planets like Earth are stellar ash. You are Earth, therefore you are also stellar ash - in part.

The elements aren't like coal, they don't form geologically. They only move around geologically.

 

[barbos]

https://astronomynow.com/2015/12/09/gamma-ray-burst-seeded-solar-nebula-with-heavy-elements/

after observing the afterglow of the short gamma-ray burst GRB 130603B, estimated that it had produced ten times the mass of the Moon in terms of gold alone.

dumbass author spelled "xenon" as "xeon"

 

[Malintent]

Not talkin about science Malintent. Just because science uses a set of rules doesn't make it own the word science. Know what I am saying? My hypothesis has been that "all religions are the same" for a while now, how ironic. Can't get any damn help with it but every day is a new day.

But yeah, my actual "hypotheses" was an attempt at a conversation about space and the mind. They're pretty similar in unknowable ways. Scary one though huh. This is where you start throwing out space facts and drawing numbers up for me, I politely ask. Disagreeing. Calling it impossible, and explaining why in simple terms. The book thing didn't quite do it for me but yeah if you look at it like that, sure that makes sense. Maybe people just don't know anything about it. I def wasn't trying to come off like I do. Yeah just too complicated.

This is all for science.

Not talkin about science Malintent

We live in a Universe full of fractals, fueling emergent complexity, using simple rules. All natural things share similarities because they all share a common set of universal rules, like gravity, the speed of light, and the charge of an electron. The scale, from microscopic to cosmic, shows repeating patterns everywhere you look.

 

[Treedbear]

...
We live in a Universe full of fractals, fueling emergent complexity, using simple rules. All natural things share similarities because they all share a common set of universal rules, like gravity, the speed of light, and the charge of an electron. The scale, from microscopic to cosmic, shows repeating patterns everywhere you look.

I was speculating that the mind, which has evolved to create models which represent its environment (and therefore the universe), is somewhat similar to a fractal in that respect. Therefore intelligence is a natural product of the universe in that it reflects its fractal nature.

 

[Loren Pechtel]

How does merging neutron stars make elements here on Earth?

1) How does anything emerge? Isn't the result inevitably a black hole?

2) Even if it doesn't go black hole how does much escape?

The crab nebula is a supernova explosion. When stars go supernova the outer shell of material gets ejected. Rocky planets like Earth are stellar ash. You are Earth, therefore you are also stellar ash - in part.

The elements aren't like coal, they don't form geologically. They only move around geologically.

Isn't most of that mass blown off an ordinary star, not from a neutron star?

 

[abaddon]

Isn't most of that mass blown off an ordinary star, not from a neutron star?

When massive stars that are 8 to 15 times the mass of our sun eventually run out of H and collapse, the gravitational pressure becomes so tremendous that the protons and electrons fuse together into neutrons. At some point there’s an implosion that flashes back and outward: a supernova. The super-hot compacted core is what remains. It’s a mass about equivalent to our sun, that’s “squeezed down” to only miles in diameter. So most of this (formerly) large star’s mass is blown out into space.

I don’t know what percent of an “ordinary” star’s mass blows out into space when it explodes and leaves a white dwarf behind. But since it’s a much smaller amount of matter to start with…

If I remember right, supernovas are estimated at about one per 50 years in our galaxy, and that could be about thirty supernovae per second universally.

 

[repoman]

So, what are the rates of supernovae and compact binary collisions in similar galaxies to ours that we see at ~4.5 billion years ago?

I would assume a fair amount higher than now.

I followed Pu-244 decay chain and if I did i right then it makes Th-232 which is pretty common.

interesting artlice semi-related:

https://www.scientificamerican.com/article/ancient-nuclear-reactor/

 

[Loren Pechtel]

Isn't most of that mass blown off an ordinary star, not from a neutron star?

When massive stars that are 8 to 15 times the mass of our sun eventually run out of H and collapse, the gravitational pressure becomes so tremendous that the protons and electrons fuse together into neutrons. At some point there’s an implosion that flashes back and outward: a supernova. The super-hot compacted core is what remains. It’s a mass about equivalent to our sun, that’s “squeezed down” to only miles in diameter. So most of this (formerly) large star’s mass is blown out into space.

I don’t know what percent of an “ordinary” star’s mass blows out into space when it explodes and leaves a white dwarf behind. But since it’s a much smaller amount of matter to start with…

If I remember right, supernovas are estimated at about one per 50 years in our galaxy, and that could be about thirty supernovae per second universally.

Ordinary stars can't produce heavy elements anyway, how much gets blown off isn't relevant to this.

I had long understood that the primary source of heavy elements was stuff thrown off in supernovas--a decent portion of the mass of the star goes flying and it's a total soup of elements including the heavies.

 

[repoman]

Much like how spectrosopy is way oversimplified in school (there are many more ways for light to interact with matter), I think that the model of normal large stars not making any elements well past iron is simplified. If there is enough excess energy available they will be produced before a supernova. How often they revert back to iron I am not sure about.

 

[bilby]

When massive stars that are 8 to 15 times the mass of our sun eventually run out of H and collapse, the gravitational pressure becomes so tremendous that the protons and electrons fuse together into neutrons. At some point there’s an implosion that flashes back and outward: a supernova. The super-hot compacted core is what remains. It’s a mass about equivalent to our sun, that’s “squeezed down” to only miles in diameter. So most of this (formerly) large star’s mass is blown out into space.

I don’t know what percent of an “ordinary” star’s mass blows out into space when it explodes and leaves a white dwarf behind. But since it’s a much smaller amount of matter to start with…

If I remember right, supernovas are estimated at about one per 50 years in our galaxy, and that could be about thirty supernovae per second universally.

Ordinary stars can't produce heavy elements anyway, how much gets blown off isn't relevant to this.

I had long understood that the primary source of heavy elements was stuff thrown off in supernovas--a decent portion of the mass of the star goes flying and it's a total soup of elements including the heavies.

Note that the chart in the OP is about the source of elements found on Earth, not the source of those elements in the wider universe. That a GRB caused by merging neutron stars contributed more to the local mix than is typical elsewhere will inevitably skew the results.

 

[barbos]

Much like how spectrosopy is way oversimplified in school (there are many more ways for light to interact with matter), I think that the model of normal large stars not making any elements well past iron is simplified. If there is enough excess energy available they will be produced before a supernova. How often they revert back to iron I am not sure about.

Even if you somehow got star generate some tiny amount of heavier than iron elements you still need to get it out somehow and there is not other way than supernova.