# QuestionHow many times has our matter cycled through the stellar life cycle?

#### Canukanaut

We all know that the Universe started with Hydrogen with a lesser amount of Helium and a trace of Lithium. As these elements went through the stellar process they combined to form the heavier elements of the Periodic Table. Therefore, knowing the rate of stellar processing and the rate at which elements are formed, could we use the ratio of elements in our own Solar System to calculate how many times the matter that makes us and our Solar System up has passed through the stellar process? We by necessity must be at least second generation matter. Just as likely we may be third generation matter. Could we have gone through the process 4 or 5 even 6 times to end up with the ratio of elements we see today? Is there another way to calculate how many times our bodies have gone through the stellar life cycle? I am wondering how many times we have been recycled to end up as we are with the solar system we have now?

rod and dfjchem721

#### Helio

You might find this Wiki article helpful.

Astronomers label the very first stars (mainly hydrogen as you say) as Population III stars. These produced the heavier elements, which became mixed into the still high concentration of hydrogen and helium. These heavier elements ("metals") assisted the next phase of star formation - Population II stars. More recent formation, not surprisingly, are the Population I stars, which have more metals than the prior populations.

rod and dfjchem721

#### Helio

Also, here is a cool table of the elements that shows what events produced each one.

dfjchem721

#### Canukanaut

Also, here is a cool table of the elements that shows what events produced each one.
So your guessing we are third generation matter. That is three cycles of the stellar process in 13.8 billion years that has brought us to this point.
Does anyone else have an opinion? I figured third generation but what about fourth?

dfjchem721

#### Catastrophe

##### The devil is in the detail
"Therefore, knowing the rate of stellar processing and the rate at which elements are formed, could we use the ratio of elements in our own Solar System to calculate how many times the matter that makes us and our Solar System up has passed through the stellar process?"

If there are so many star types with different rates of producing different elements (differing growth paths) and differing life spans I would have thought it very difficult (to do as you suggest). However, that is just my gut feeling, not a scientifically derived prognostication.

dfjchem721

#### dfjchem721

It would seem the answer could be an "average" of stars that we have been through. Clearly everything higher than iron had to have formed in a core collapse supernova (SN), so there is at least one star. Now all of that SN debris, as it races out into the galaxy, should begin to mix with other gases and dust that is drifting through the general neighborhood.

Not all of this material mixing with the debris from the SN is necessarily from another star. Some of it could be "virgin hydrogen", never before condensed into a star, but pushed here and there by shock waves, or has "recently" joined the galaxy from intergalactic space either as "solo" hydrogen, or stripped from an acquired galaxy some time ago.

It seems possible the the solar system is made up of matter from a variety of solar cycles, so perhaps the better question might be "what is the solar cycle average value" for our atomic composition. Since it has matter from at least one SN, the number must be greater than or equal to 1. Considering all of the lower elements, the answer might actually have to be greater than or equal to 2,

Maybe there is some expert out there who can clarify this. I would still bet on an "average cycle number" rather than a "precise cycle number".

Catastrophe

#### dfjchem721

All stars have a characteristic known as metallicity*. The lower the metals, the older the stars. The higher the metals, the younger the stars. Based on wiki's Stellar population** info:

"Population I, or metal-rich, stars are young stars with the highest metallicity out of all three populations, and are more commonly found in the spiral arms of the Milky Way galaxy. The Earth's Sun is an example of a metal-rich star and is considered as an intermediate Population I star."

Note the term "intermediate ". This suggests as noted earlier that these stars and their systems likely have a fractional star cycle number.

also from same wiki article:

"Population I stars usually have regular elliptical orbits of the galactic center, with a low relative velocity. It was earlier hypothesized that the high metallicity of Population I stars makes them more likely to possess planetary systems than the other two populations, because planets, particularly terrestrial planets, are thought to be formed by the accretion of metals. However, observations of the Kepler data-set have found smaller planets around stars with a range of metallicities, while only larger, potential gas giant planets are concentrated around stars with relatively higher metallicity — a finding that has implications for theories of gas giant formation.[16] Between the intermediate Population I and the Population II stars comes the intermediary disc population. "

end quote

Again, we see the term intermediate, which one might infer that there are a range of Population I stars, perhaps based on their "average star cycle".

This is a clearly interesting line of inquiry, thanks to Canukanaut.

* https://en.wikipedia.org/wiki/Metallicity

** https://en.wikipedia.org/wiki/Stellar_population#Population_I_stars

Catastrophe

#### rod

FYI, presently BBN is missing a key ingredient in astronomy, the Population III stars or first generation. See https://phys.org/news/2020-06-hubble-early-universe.html and https://arxiv.org/pdf/2006.00013.pdf

Note the summary in the arxiv report: "All these results suggest that even with the deepest HST imaging possible, we are still not reaching the first stars and galaxies at z ~ 9. It is clear that galaxy and structure formation predates even this very early redshift, showing that many galaxies will be found at even higher redshifts. JWST will certainly provide a clearer picture of this when it examines galaxies at even higher redshifts where ultimately Pop III stellar populations will be discovered."

Apparently, the most distant galaxy shown by Spitzer is not known to have Population III stars either, ‘Characterizing the Environment Around The Most Distant Known Galaxy’, https://ui.adsabs.harvard.edu/abs/2019hst..prop15977O/abstract, GN-z11

In the 1970s, searches for Population III stars looked at red dwarfs. None found. Population III star equation-of-state (EOS) modified to make them larger, burn faster, and disappear earlier in BB cosmology while seeding the early universe with r-process and s-process elements. Astronomy is correct to search for this type of star based upon the BB cosmology model and BBN. So far Population III stars remain undiscovered unlike a star like Arcturus or observations of the Galilean moons at Jupiter. The first generation of stars must be assumed in any stellar generation count for our Sun and if they never existed, problems arise in BB cosmology concerning what the primordial chemistry of the early universe was.

Catastrophe

#### Catastrophe

##### The devil is in the detail
Rod, I for one would greatly value your comments on title subject, in relation to my suggestion of spread of star types, particularly noting "New results from the NASA/ESA Hubble Space Telescope suggest the formation of the first stars and galaxies in the early Universe took place sooner than previously thought." from your reference.

I cannot see why the great diversity of types and circumstances would not preclude meaningful calculation.

rod

#### rod

Catastrophe, I see your thinking here about *meaningful calculation* concerning r-process and s-process mixing, thus what generation is our Sun based upon its chemical abundances compared to the BB event and assumed, Population III stars that formed first in the early universe. Tackling a *meaningful calculation* I am not sure about here Cat. Here are some notes from me. Space.com reported on the solar abundances in this past article, https://www.space.com/17170-what-is-the-sun-made-of.html. We have other reports like ALMA's image of a red giant star gives a surprising glimpse of the sun's future Here is a comment from that phys.org report. "It's humbling to look at our image of W Hydrae and see its size compared to the orbit of the Earth. We are born from material created in stars like this, so for us it's exciting to have the challenge of understanding something which so tells us both about our origins and our future," she says."

Reporting like this is popular and common but *meaningful calculation*? I will use Betelgeuse in Orion as an example. Wikipedia reports Betelgeuse has an iron/hydrogen ration [Fe/H] = +0.05 and stellar mass about 12 solar masses, https://en.wikipedia.org/wiki/Betelgeuse Using the Sun as a model and abundances, that works out to be about 62759 earth masses of iron, potentially in Betelgeuse. A one solar mass star would be about 5230 earth masses of iron using the Betelgeuse [Fe/H] content. What constraints are there in astronomy that show *meaningful calculation*, how many new earths with new life containing Betelgeuse iron in their blood, is likely to evolve from the iron in Betelgeuse and over what time span?

The thread here did ask a good question "I am wondering how many times we have been recycled to end up as we are with the solar system we have now?"

Catastrophe

#### Catastrophe

##### The devil is in the detail
Rod, thank you so much. You have obviously put in a great deal of effort which I appreciate. I am primarily interested in planetary sciences so this will take me a while to digest.

My reaction on seeing the question was to ask whether such a question is answerable. Had we been the result of one cycle, and if we knew the type and distance of local stars (and whether these included first stars) I guess some answer might be possible. As you widen the net the difficulty, I thought, would certainly increase. So this comes back to whether the question is answerable with any meaningful degree of certainty?

My initial thought was to look at a modified Periodic Table like that contained in:

Just go down a little.

and try to estimate what elements were produced in each star type (and their fate) and which might be within range of supplying our Sun with those elements.

On re-reading the question (how many times were we told to do that) I realise that much of this is already stated in the opening question itself. Combining the Periodic Table modification I referenced, I can see a way through, but it requires (as far as I can see) a terrific amount of research.

If I can rephrase my question:

In your opinion, is the question answerable at all within the bounds of meaningful possibility? If so, would the effort be worthwhile?

I do not want you, please, to spend any more time on this. Just off the top of your head will suffice.

dfjchem721

#### Catastrophe

##### The devil is in the detail
Now I have just seen that #4 references the same modified Periodic Table.
My apologies to all.

dfjchem721

#### rod

Catastrophe, I have no answer concerning a *meaningful calculation* for the solar abundance and how many generations of stars were involved going back to Population III stars and the primordial gas clouds in BB cosmology that shows the Sun iron abundance today. Using the Sun'r iron or metallicity, we have the Sun's [Fe/H] = 0 on the scale so the amount of iron is 4.6612E+03 earth masses in the Sun. How many different stars were involved creating this iron amount before the solar nebula formed? It is clear from Betelgeuse that the red super-giant has more than enough iron mass to do this without multiple generations before the solar nebula is said to create our Sun and solar system I can apply the same to the exoplanet, TOI-503 b. Its host star is 1.8 solar masses and [Fe/H}=0.61. The iron mass content in this star is 3.4180E+04 earth masses, ref http://exoplanet.eu/catalog/toi-503_b/. Similar problem arises as our Sun, how many stellar generations needed here to explain all that iron in the host star of TOI-503 b exoplanet? My concern - where are the constraints in the popular science reporting about this issue? Popular reporting says we are made out of star stuff but that is easy to say, harder to show and the iron abundance is a simple place to start.
 ​

Catastrophe

#### Helio

Now I have just seen that #4 references the same modified Periodic Table.
My apologies to all.
I like yours better. Your link shows 8 ways to make elements, where the one I used only shows 6.

Catastrophe