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What's the third most common element?

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Re: What's the third most common element?

#31

Post by scotty79 »

analog31 wrote: post #28
scotty79 wrote: post #25

Is big bang necessary for this or does any amount of photons of insanely high energy crystallize in matter in those proportions?

As I understand it, something like the big bang produces mostly light elements -- hydrogen and helium. Everything else is produced in the stellar fusion machine plus supernovas. So, by the time that the heavier elements are forming, the big bang has been done with and forgotten about for at least, like a microsecond. ;-)

I was referring to creation of hydrogen, helium and traces of some others like lithium.

Thinking about what you said I think necessary condition to get big bang hydrogen/helium ratio is that although there must be very high energy density we must not have too much of gravitational confinement because that would spark fusion and mess up the ratio bringing to closer to what we have currently in the universe.

Re: What's the third most common element?

#32

Post by raverbashing »

dannypgh wrote: post #27
raverbashing wrote: post #16

Earlier quoted context omitted.

https://en.wikipedia.org/wiki/Water#In_the_universe While water will break down at high temperatures I would find it surprising that 1st and 3rd most common elements in the whole universe, that readily combine to form water would not result in substantial amounts of water. It's probably like saying we shouldn't find H2 because "nothing says they are found bound together"

Most atoms- and certainly most hydrogen- are in stars, no? Not exactly places where water "breaking down at high temperatures" (really, never forming) can be ignored.

Yes, I guess not even H2 is much stable in stars.

I would expect that in planet formation situations

Re: What's the third most common element?

#33

Post by gus_massa »

scotty79 wrote: post #25

Is big bang necessary for this or does any amount of photons of insanely high energy crystallize in matter in those proportions?

The Hydrogen-Helium ratio is very related to the details of the Big Bang. From http://hyperphysics.phy-astr.gsu.edu/hbase/astro/hydhel.html

> Basically, the hydrogen-helium abundance helps us to model the expansion rate of the early universe. If it had been faster, there would be more neutrons and more helium. If it had been slower, more of the free neutrons would have decayed before the deuterium stability point and there would be less helium.

Re: What's the third most common element?

#34

Post by simonh »

mrfusion wrote: post #30
simonh wrote: post #26

Earlier quoted context omitted.

At the universal scale, we can observer several galaxies in various stages of colliding with each other (1). In fact our galaxy and Andromeda are on course to collide with each other in about 4 billion years (2). Massive stars end their lifecycle in a supernova explosion, which blasts much of their mass off into space. the remaining stellar core either forms a neutron star or a black hole. The mass that is blated off…

Interesting. So where did our sun come from? Are you saying it started from a multilight year wide cloud? Why is it 4+ light years from any other stars? Did our sun pull everything out of that radius when it was forming leaving a whole bunch of empty interstellar space?

Bear in mind the galaxy is continuously rotating, our sun is orbiting the galactic nucleus, as are the other stars around it. Right now the nearest star is 4 lightyears away, but that's not always the case and it's quite likely other stars have passed ours by much closer than that during it's lifetime. In fact our sun has orbited the galactic core many times; it does so roughly every 250 million years.

The sun would have accumulated material from the nebula it formed in as it drifted though it. The stars near us now are not the ones our sun was near when it formed though (except by extemely unlikely co-incidence), as each star is on a slightly different course round the galaxy, like water droplets in a very slowly rotating cyclone.

If another star were to pass by very close, it could be disastrous for us as it could severely disrupt the planetary orbits in our system, but that's fairly unlikely and there's no prospect of that happening for many millions of years at least. The space between stars is vast, even by comparrison to the size of stars themselves and their solar systems.

EDIT - on that last point, 4 ly is ~250,000 AU (the distance from the earth to the sun). If we asume out solar system is 100 AU across, that's still only 1/2500 the distance to the next star.

Re: What's the third most common element?

#36

Post by scotty79 »

gus_massa wrote: post #33
scotty79 wrote: post #25

Is big bang necessary for this or does any amount of photons of insanely high energy crystallize in matter in those proportions?

The Hydrogen-Helium ratio is very related to the details of the Big Bang. From http://hyperphysics.phy-astr.gsu.edu/hbase/astro/hydhel.html > Basically, the hydrogen-helium abundance helps us to model the expansion rate of the early universe. If it had been faster, there would be more neutrons and more helium. If it had been slower, more of the free neutrons would have decayed before the deuterium stability point and…

> If it had been faster ... > If it had been slower ...

Isn't the inflation conceived to be as fast and long as necessary so that inputs to baryogenesis give result with hydrogen to helium ratios that are in line with experimental data?

Re: What's the third most common element?

#39

Post by [deleted] »

natejenkins wrote: post #11

What caught my eye was the oscillation in the abundancy graph, there is a tendency for even atomic number elements to be more abundant than odd atomic number elements. Looking at the original Wikipedia article leads to the Oddo-Harkins rule http://en.wikipedia.org/wiki/Oddo%E2%80%93Harkins_rule . There is more discussion on the stability of even vs odd atomic number elements here: http://en.wikipedia.org/wiki/Even_an…

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